geology 1eso ud03 lp - blinklearning · geology_1eso_ud03_lp.indd 100 25/03/15 10:02. 101 the...

3 The Geosphere

100

THE GEOSPHERE

In this unit, students will learn about the solid part of the Earth. It is very important to highlight the link between the origin of our planet and its layers, as well as the importance that minerals and

rocks have for humans and in our daily lives.

Competences and Objectives

KEY COMPETENCES LEARNING OBJECTIVES

Linguistic communication (LC)

Mathematical competence and key competence in science and technology (MCST)

Learning to learn (LL)

Digital competence (DC)

Social and civic competence (SCC)

Cultural awareness and expression (CAE)

Sense of initiative and entrepreneurship (SIE)

❚ Understand the origins of the Earth.

❚ Differentiate between the layers of the Earth and describe the characteristics of the materials they are composed of.

❚ Identify minerals and their properties.

❚ Identify and classify rocks.

❚ Value the importance of minerals and rocks for humans and of managing these resources in a sustainable way.

❚ Carry out a research task.

Suggested TimingThis unit can be worked on over a period of four weeks (approximately twelve sessions). The number of sessions should be determined by the interest that students show for the content, and how the general unit planning takes place.

Sections N.° of sessions

Warmer 1

1. The Earth: origin and composition 1

2. Minerals 2

3. Rocks 3

4. The use of rocks 1/2

5. Extraction of minerals and rocks 1/2

Consolidation 1

Work and experimentation techniques 1

Final task 1

Self-assessment 1

Mixed-ability needs In order to meet the needs of different students, a wide variety of resources are offered as complements or alternatives to the work in the unit: worksheets, lesson summaries and slide presentations with core content and curricular adaptations.

It is at the discretion of the teacher that these resources are used, although suggestions are given in every lesson.

3

GEOLOGY_1ESO_Ud03_LP.indd 100 25/03/15 10:02

101

3The Geosphere

U N I T L E S S O N P L A N

Contents Assessment criteria Learning outcomes

The Earth: origin and composition❚ The origin of the Earth❚ Studying the Earth’s interior❚ Layers of the geosphere

1. Understand the origins of the Earth. 1.1. Describe the formation process of the Earth. (LC, MCST)

2. Relate the layers of the geosphere and its formation processes.

2.1. Relate the layers of the geosphere and its formation processes. (MCST, LL)

3. Differentiate between the layers of the Earth and its characteristics.

3.1. Describe the main characteristics of the most frequent materials in the external areas of the planet and explain their distribution according to the density. (LC, MCST, LL)

3.3. Describe the main characteristics of the crust, the mantle and the core and the materials that formed them. (LC, MCST, LL)

Minerals❚ Properties of minerals❚ The importance of minerals❚ Sustainable management of mineral resources

4. Understand the concept of mineral and apply it to recognise if certain substances are minerals or not.

4.1. Understand the concept of mineral. (LC, MCST)

4.2. Apply the concept of mineral to recognise if certain substances are minerals or not. (LC, MCST, SCC)

5. Differentiate minerals according to their properties. 5.1. Identify minerals using information that could differentiate them. (LC, MCST, DC, SCC)

6. Highlight the importance of minerals. 6.1. Describe some of the most frequent uses of minerals in our daily life. ( MCST, DC, SCC)

Rocks❚ Igneous or magmatic rocks❚ Sedimentary rocks❚ Metamorphic rocks❚ The rock cycle

7. Understand the concept of rocks and their classification.

7.1. Understand the concept of rock. (LC, MCST)

7.2. Recognise the three types of rock according to their origin and identify the main characteristics of each one. (LC, MCST)

8. Differentiate rocks according to their origin. 8.1. Identify rocks using information that could differentiate them. (MCST, SIE)

The use of rocks 9. Describe the most frequent use of rocks in our daily life.

9.1. Describe some of the most frequent uses of rocks in our daily life. (MCST, DC, CLL)

Extraction of minerals and rocks 10. Value the importance of minerals and rocks for humans and of managing these resources in a sustainable way.

10.1. Recognise the importance of minerals and rocks for humans and of managing these resources in a sustainable way. (LC, MCST, DC)


3 The Geosphere

102

TEA

CH

ER R

ESO

URC

ESST

UD

ENT

RESO

URC

ES

UNIT CONTENT MAP

Video: Lithium for petroleum

Conceptual mapPresentation

Video: The origin of the EarthReading comprehension: The core of the Earth rotates much slower than you think Reading comprehension:

The rock of agesWeb page: Identifying rocks

Web page: The quarryVideo: A Day without minerals

1. The Earth: origin and composition

1.1. The origin of the Earth

1.2. Studying the Earth’s interior

1.3. Layers of the geosphere

1.3.1. The Crust 1.3.2. The Mantle 1.3.3. The Core

2. Minerals 2.1. Physical properties of minerals 2.1.1. Optical properties 2.1.2. Mechanical properties 2.1.3. Magnetic properties 2.1.4. other properties of

materials 2.2. The importance of minerals 2.2.1. Metal ores 2.2.2. Raw materials for industries 2.2.3. Gems or precious stones 2.3. Sustainable management of

mineral resources

3. Rocks 3.1. Igneous or magmatic

rocks 3.2. Sedimentary rocks 3.2.1. Formation of

sedimentary rocks 3.2.2. Classification of

sedimentary rocks 3.3. Metamorphic rocks 3.4. The rock cycle

4. The use of rocks

Unit 3. The Geosphere

Oxford investigation > > > > > >

Reinforcement activities > > > > > >

Curricular adaptation worksheets > > > > > >

Science practical: The hardness of minerals

Interactive activities > > > > > >

Talking book > > > > > >


103

3The Geosphere

Web page: Gold extraction and its use

Web page: The crust and its matter.

Conceptual mapPresentationReinforcement activities

Extension activitiesCurricular adaptation assessment Assessment

Reinforcement activitiesExtension activitiesCurricular adaptation worksheet

5. Extraction of minerals and rocks

Consolidation Work and laboratory practical techniques

Final task

Unit 3. The Geosphere

Oxford investigation > > > > > >

Reinforcement activities> > > > > >

Curricular adaptation worksheets> > > > > >

Interactive activities> > > > > >

Talking book> > > > > >


3 The Geosphere

104

At the beginning of the unit, the objectives are already established and they should be linked to the learning outcomes. Students will have a clear idea about the topics

as well as what they will learn throughout the unit.

Before playing the video, ask questions so that the students can think about them while watching it. It is a very useful way to check if students understood the explanations that appear in the video.

Video: LITHIUM FOR PETROLEUM

The video is about the materials extracted from the geosphere and the use of them nowadays in developed countries. Play until minute 4:50.

After watching the video, discuss the following and elicit answers from the students.

Jules Verne, in his book called Journey to the centre of the Earth, explains how the interior of the Earth was.

❚ What do you think the Earth is like in its interior? Could we travel there?

No, because the temperature and the pressure in the interior of the Earth are unbearable to humans.

Minerals are widely used for jewelry as precious stones after a process of cutting and polishing.

❚ What qualities make some minerals so appreciated by people?

The main qualities are the hardness, the lustre and the colour as well as the transparency.

Rocks are used for construction. ❚ What else can rocks be used for?

Rocks also have ornamental uses and can be used as fossil fuels or as a source of minerals for technological uses.

Superficial extractions are more profitable than subterranean extractions. ❚ Why do you think it’s important to manage mineral resources responsibly?

Because superficial extractions have a great impact on the environment, killing all living things in the area.

❚ What can you see in the photo? Where do you think it is?

PRESENTATION

Use the slideshow presentation to show the different sections in the unit and to evaluate student’s prior knowledge. This tool can also be used as revision at the end. The slides can stimulate student participation, as they can be asked about certain topics before they study them.

Point out the Final task to the students: The environmental impact of mineral extraction. Explain what the task is: an oral presentation with slideshows and in groups.

● Understand the origins of the Earth.

● Differentiate between the layers of the geosphere and describe the characteristics of the materials they are composed of.

● Identify minerals and their properties.

● Identify and classify rocks.

● Value the importance of minerals and rocks for humans and of managing these resources in a sustainable way.

● Carry out a research task.

3YOU WILL LEARN TO…

THE GEOSPHERE

What do you think the Earth is like in its interior? Could we travel there?

What qualities make some minerals so appreciated by people?

Rocks are used in construction. What else can rocks be used for?

Why do you think it’s important to manage mineral resources responsibly?

What can you see in the photo? Where do you think it is?

Final task +www

473. The geosphere

The environmental impact of mineral extraction

Minerals are extremely useful to us. Minerals have great economic value and are often obtained without thinking about the environmental and social impact of their extraction.

Mineral extraction in third world countries is directly related to smuggling, poor work conditions and child labour.

One of the most sought after minerals is coltan, which is used to the make parts of electronic devices. In this unit, you will research this mineral and create a slideshow presentation.

bg1e900

TEACHING SUGGESTIONS


105

3The Geosphere

Read the task with students and explain that the steps to carry out the final task are on page 65.

By carrying out the final task you will be working the following key competences:

❚ Linguistic communication (LC). In the oral presentation that will take place in the classroom.

❚ Mathematical competence and basic competences in science and technology (MCST). Throughout the unit.

❚ Digital competence (DC). When searching for information.

❚ Learning to learn (LL). When following a study technique which helps the learning process.

❚ Sense of initiative and entrepreneurship (SIE). When students decide by themselves which information is useful for their work.

❚ Social and civic competences (SCC). When participating in group work.

In the first session you could introduce the vocabulary suggested in the section Study skills on page 63. Students search for the

meaning of the words and write them down in their notebook in alphabetical order, thus creating a scientific glossary. Thus students will have exposure to the vocabulary and will be more prepared to start the unit.

CONCEPTUAL MAP

To introduce the contents of the unit, you could show an incomplete conceptual map and ask them to complete the gaps in their notebook or orally with the whole group. This will help students to visualise the links between the different contents of the unit.

OXFORD INVESTIGATION

It starts with an introduction of the unit with some preliminary questions and the final task that should be carried out after finishing the activities. The final task is normally a practical problem whose solution demands a variety of learning skills and research. Students will be given the idea that in particular activities they will learn concepts and/or the procedures that will be used to sort out the practical problem.


3 The Geosphere

106

1. The Earth: origin and compositionBefore or after reading each section, listen to the Talking book.

1.1. The origin of the EarthBefore starting this section, remind students about the concepts of density and gravity. It will help them to understand clearly the origin of our planet.

It is important that students differentiate the concepts of density and mass. Otherwise, they will not be able to understand the process of density differentiation. You can take a scale to the classroom, a small pebble and a big cork. Make sure the cork weighs more than the pebble. Put the cork and the pebble in a bow with water and ask them to observe what happens. The cork will float and the pebble will sink. This is a practical and visual way to understand the difference between these two concepts.

Show the video.

Video: THE ORIGIN OF THE EARTH

This video is about how the planets were formed. The presenta-tion of the video and the answers to the questions will help stu-dents to deepen their understanding of the following question: After hearing about the Big Bang theory about the formation of the universe, how do you think the Earth was formed?

1.2. Studying the Earth’s interiorFor students it is always a mystery to know the interior of the Earth without being there. They should understand that the waves produced by an earthquake are the same as the ones when you throw a pebble into a pond. Those waves travel on the surface of the

water as well as in its interior and the same process happen to the waves produced by the earthquakes. Light waves are deflected when they pass from air to water and it makes us see a stick in the water as if it was crooked. The same happens to the seismic waves when they are deflected from one place to the other. Those deflections affect the speed of the wave transmission through the interior of the layer. This way, and also because of the seismographs, we are able to know the internal structure of the planet.

On the planet there are lots of network seismographs to detect any earthquakes that could happen in the crust. At least three seismographs are needed to precisely detect the epicenter of an earthquake.

1.3. Layers of the geosphereA practical way to explain the layers of the geosphere is to make a chart where students can compare depth, density, state of the materials and its composition. This chart will help students to easily follow the explanations and understand the contents

Layers of the geosphere

Depth Density Physical state Composition

Crust

Continental crust Up to 70 km 2,7 g/cm3 Solid Granite, clay...

Oceanic crust Up to 10 km 3 g/cm3 Solid Basalt

Mantle

Upper mantle Up to 670 km 3,3 g/cm3 Solid Peridot

Lower mantle Up to 2 900 km 5,5 g/cm3 Solid Peridot

Core

Outer core Up to 5 120 km 10,6 g/cm3 Liquid Iron

Inner core Up to 6 370 km 13 g/cm3 Solid Iron

48 493. The geosphere

3 +www

1. THE EARTH: ORIGIN AND COMPOSITION

The Earth is the third closest planet to the Sun. It is a rocky planet and the only planet that has water in all three states. As a result, it is the only planet with living things.

The Earth can be divided into four layers: the geosphere or solid layer; the atmosphere or gaseous layer; the hydrosphere which contains water in all three states and the biosphere where life exists.

1.1. The origin of the Earth

According to the latest studies, 4 600 billion years ago the Sun formed from chemical reactions in a giant cloud of dust and gas, called a nebula. In the cloud of matter that surrounded the Sun, smaller dust particles collided and grew in size. This process which formed the planets is called accretion of planetesimals.

For 1 000 million years the Earth was incredibly hot. Due to the immense heat stored in the Earth’ s interior, there was a lot of volcanic activity during this period. As the Earth’ s temperature decreased, gravity pushed denser materials, such as iron, towards the Earth’ s interior. Less dense materials, such as oxygen, moved towards the Earth’ s surface. This process is called density differentiation. As the Earth cooled, it maintained this structure of layers.

1.2. Studying the Earth’ s interior

The Earth’ s is 6 370 km at the Equator but we only have direct knowledge of the most superficial layers under the Earth’ s surface. Mines or drill holes1 have allowed us to reach depths of 8 -12 km.

To understand the composition of the Earth’ s interior, scientists have to use indirect methods. The most common method is the study of earthquakes called the seismic method. This method analyses the energy generated by earthquakes.

When you throw a pebble into water, the water moves across the surface in all directions in waves. Similarly, when an earthquake occurs, the movement generates waves of energy that travel to the interior of the Earth, called seismic waves. These waves can be detected by an apparatus called a seismograph. This shows us that the speed of the waves vary as they pass from one layer to another.

The study of the data obtained from seismographs has allowed scientists to deduce the composition of the Earth’ s interior. This information has been used to create a model of the Earth’ s structure. It is divided into three layers: the crust, mantle and core.

1.3. Layers of the geosphere

The solid part of the Earth is divided into different layers separated by areas known as discontinuities. In these areas the seismic waves change velocity. This allows us to identify where each layer ends.

1.3.1. The crust

This is a thin layer covering the Earth’ s surface and it is the least dense layer. There are two types of crust:

❚ The continental crust is more than 1 000 million years old and it is between 10 and 70 km thick. The continental shelf, continents and islands are all part of the continental crust. It is composed of rocks such as granite, clay and slate.

❚ The oceanic crust is 200 million years old and it is between 6 and 10 km thick. It forms the seafloor and is composed mainly of basaltic rock.

1.3.2. The mantle

The density of this layer varies. It is composed mainly of a type of rock called peridot. The mantle has two parts.

❚ The upper mantle has a higher density than the crust and it is solid. However, scientists have discovered some areas of liquid or molten rock.

❚ The lower mantle is the densest layer of the mantle and contains materials in a solid state.

1.3.3. The core

This is the most internal and densest layer of the geosphere. It is composed mostly of iron, although other metals such as nickel can be found. It is divided into two layers.

❚ The outer core is not as dense as other layers. It is composed of molten materials and it is constantly moving.

❚ The inner core has the densest materials. It is the hottest layer. Even though the temperatures are so hot, the materials in this layer are in a solid state due to the immense pressure found in it.

Key concepts

❚ The Earth formed by the process of accretion of planetesimals. The materials that make up the Earth were distributed in layers according to their density.

❚ There are three layers in the geosphere: the crust (continental and oceanic), mantle (upper and lower) and the core (outer and inner).

1drill hole: a perforation in the ground in order to study the rocks under the Earth’ s surface

Seismograph

Formation of the Solar System

Layers of the geosphere and discontinuities that separate them

Understand

1. Explain in your own words the meaning of accretion of planetesimals.

2. Listen and find the parts of the geosphere on the diagram.

Create

3. Find out about the density of the layers of the geosphere. Make a table with the information in the order of least dense to densest materials.


107

3The Geosphere

The seismographs detect the variations of the seismic wave’s velocity that are related to the discontinuities. These discontinuities are named according to the person who discovered them. Only the outer core is liquid, although by analysing how the seismic waves move, we can deduce that in the mantle there are materials partially molten that reduce the velocity of the waves. In the chart we only see the main materials but students must know that there are other materials, especially in the crust. They will study those in this unit

The layers of the geosphere are divided according to their composition. There is another division according to their conduct or dynamism. It says that the geosphere is divided into: lithosphere (the crust and part of the upper mantle), sub-lithospheric mantle (rest of the upper mantle), lower mantle, outer core and inner core.

When explaining the mantle, highlight that the materials partially molten and the high temperatures generate movements called convection currents. Those movements move the lithospheric plates.

The core generates a magnetic field that allows us to find directions using a compass and also protects us from harmful solar radiations.

Finish the section by asking them to do questions 1 to 3 and then review the Key concepts at the end of the section.

Tips: Question 1 should be done with the whole class. Before question 2 give the students time to look at the diagram first, then play the audio twice. Ask students to do question 3 individually and then ask them to compare their answers. Correct with the whole class.

Reading comprehension: THE CORE OF THE EARTH ROTATES MUCH SLOWER THAN YOU THINK

This text is to emphasise the impact that the core movements have on the rest of the planet. The core is not a static or cons-tant layer; it moves and grows slowly but continuously. The core movements are very important for the planet, for example, in the creation of a magnetic field.

Curricular adaptation: 1. LAYERS OF THE GEOSPHERE

Section adapted according to the curriculum.

Answer key

Understand

1. Explain in your own words the meaning of accretion of planetesimals.

Process which formed the planets. Billions of years ago the Sun formed from chemical reactions in a giant cloud of dust and gas (nebula) and in the cloud of matter that surrounded the Sun, smaller dust particles collided and grew in size.

2. Listen and find the parts of the geosphere on the diagram.

a) The crust.

b) The oceanic crust.

c) The upper and lower mantle.

d) The core.

Audio script:

a) This is the least dense layer.

b) This is 200 million years old.

c) The mantle has two parts, what are they?

d) This is the densest layer of the geosphere.

Create

3. Find out about the density of the layers of the geosphere. Make a table with the information in the order of least dense to densest materials.

The continental crust has an average density of 2.7 g/cm3, while the oceanic crust has a higher density, with an average of 3.0 g/cm3. Consequently, the layers of the geosphere from the least to the more dense are:

Continental crust (2.7 g/cm3) - Oceanic crust (3.0 g/cm3) - Upper mantle (3.5 g/cm3) - Lower mantle (5.6 g/cm3) - Outer core (9.9 g/cm3) - Inner core (13.0 g/cm3).


3 The Geosphere

108

2. MineralsAsk the students: How do you differentiate a mineral from a rock?

At this stage, students tend to mix up the concepts of mineral and rock. Highlight that minerals are the materials that make up rocks.

Show them a granite rock. Explain that granite is a rock but the different colors on it are the minerals that actually formed it. Ask them again the meaning of mineral and rock and make sure they all understand the difference between these two concepts.

When you talk about the definite chemical composition, emphasise that there are some minerals that are formed by only one single chemical element such as sulphur, gold and silver. These are called native minerals. Students should now do activities 4 to 10. Below you will find suggestions for each activity.

4. Ask students to do this on their own and then compare answers.

5. Ask students to compare the two images in groups and then write the answers on the board.

6. Do this as a whole group activity.

7. Write various possible answers on the board and ask students to choose the correct one.

8. Ask students to do this quickly in groups of three and elicit answers.

9. Ask students to do this in pairs and then to compare their answers with another pair before asking a spokesperson from each group to answer.

10. Ask students to do this individually, then pick up a few of their notebooks and randomly read the definitions out loud. Students can vote on the most accurate definition. Include the answer as one of the possibilities. The diagram in the margin on page 50 should help them understand.

2.1. Physical properties of mineralsAsk students How can we distinguish one mineral from the other? Explain that the physical properties of minerals help us to distinguish one from the other. Tell them to read the text and look at the images. Then ask them to do question 11.

11. Do this activity with the whole class, then write the answer on the board and ask students to copy it.

Answer key

Remember

4. Write a list of the characteristics of minerals in your notebook.

Minerals are solid, inorganic, natural minerals. They have a definite chemical composition and usually have a crystalline structure.


3 +www


3

2. MINERALS

Minerals and rocks form part of the Earth’ s crust. Since ancient times, humans have used minerals obtained from the Earth.

In order to understand the definition of minerals we will analyse the description term by term.

❚ Minerals are solid substances. They cannot be liquid or gaseous at room temperature. This is why mercury is not considered a mineral.

❚ They are inorganic. They have not been produced by living things, unlike pearls, shells or amber.

❚ They are natural. This means they have not been made by humans, like plastic or glass.

❚ They have a definite chemical composition. They are composed of chemical elements that are always combined in the same proportion to create the same mineral. For example, galena, is a mineral formed by two chemical elements: sulphur and lead.

❚ They have a crystalline structure. This means that the particles are arranged to form a geometric structure that is repeated constantly. For example, the atoms of galena are structured to form a cubic shape.

If the arrangement of the mineral particles are visible, we call this a crystal. Crystals need enough time and space to form. In a crystal we can identify the edges, flat faces and the vertices of its geometrical shape.

Minerals are solid, inorganic, natural materials. They have a definite chemical composition and usually have a crystalline structure.

2.1. Physical properties of minerals

In nature there are more than 4 000 known minerals. We can identify some minerals by studying their physical properties, without analysing their chemical composition.

Physical properties are classified into optical, mechanical and magnetic.

2.1.1. Optical properties

Crystallisation of minerals

Crystalline structure of minerals

galena

Understand

11. Explain the difference between the colour and the streak of a mineral.

Remember

4. Write a list of the characteristics of minerals in your notebook.

Understand

5. Look at the two pink quartz roses above. Explain which one had more space and time to form.

6. Look at the photo of galena above. Can you say that it is a crystal?

7. Explain why amber is not a mineral.

8. Would you classify factory-made diamonds as minerals?

9. Is water a mineral? Explain your answer.

Create

10. Look for the definition of mineraloide. Decide if the glass in a window is a mineral or a mineraloide and explain your answer.

A mineral’s optical properties relate to how a mineral reacts to light.

❚ Habit: some minerals have very characteristic shapes that reflect their crystalline structure. For example, pyrite has cubic shapes and aragonite has hexagonal shapes.

❚ Streak: is the colour of the powder produced when a mineral is scratched. The colour of the streak does not have to be the same as the mineral. For example, solid quartz can be many different colours, but its streak is always white.

Pyrite Aragonite Galena and its streak

❚ Colour: some minerals have a very characteristic colour. Galena is rusty grey and sulphur is bright yellow. Other minerals, like quartz, can be found in different colours, as seen in the images below.

❚ Lustre: describes how the mineral reflects light. It can be metallic if it shines like metals, glassy if it is like glass, pearly, if it shines like a pearl, diamond-like, or dull if it doesn’t shine.

Blue quartz Transparent quartz Metalic: magnetite Glassy: fluorite Pearly: gypsum

Pink quartz Sulphur Diamond-like: rutile Dull: limonite


109

3The Geosphere

Understand

5. Look at the two pink quartz roses. Explain which one had more space and time to form.

The pink quartz on the left was probably developed with more space and time as we can appreciate with a naked eye that it is more compact. The crystal has edges, vertices and more defined and appreciable flat faces.

6. Look at the photo of the galena above. Can you say that it is a crystal?

Yes, because it has a crystalline structure and a cubic shape.

7. Explain why amber is not a mineral.

Basically, amber is not a mineral because it is not inorganic. That means that it was produced by a living thing and consequently is a petrified or fossilised vegetal resin.

8. Would you classify factory-made diamonds as mineral?

Factory-made diamonds do not have a natural origin, they are made by human beings and are not minerals.

9. Is water a mineral? Explain your answer.

Water in liquid state is not a mineral. But in solid state, as in ice cubes, and with the condition that a human being has not intervened in its formation, it is considered a mineral by the majority of scientists, although there is always a controversy about this theory.

Create

10. Look for the definition of mineraloide. Decide if the glass in a window is a mineral or a mineraloide and explain your answer.

A mineraloide is a solid substance, natural material, and inorganic. It has a definite chemical composition and similar mineral characteristics but without a crystalline structure. Its particles are not organised as they are in minerals and a mineraloide does not have a geometrical shape. It is so called non-crystalline. The glass in a window is a mineraloide or an amorphous substance.

Understand

11. Explain the difference between the colour and the streak of a mineral?

A streak is the colour that is produced when a mineral is scratched, it does not have to be the colour of the mineral.

Laboratory practical: THE HARDNESS OF MATERIALS

This laboratory practical is a good way to motivate students and it will probably make them more interested in the contents that will be seen during this unit. By doing it, students will become familiarized with a couple of minerals and also will have a clear idea of the concept of hardness.

Web page: THE QUARRY

Minerals are solid and part of the rocks. These are extracted from the interior of the crust. On this web page, students will learn more about the properties of minerals and also identify some of them.

Curricular adaptation: 2. MINERALS



3 The Geosphere

110

2.1.2. Mechanical properties Ask students to read the text and look at the table illustrating Mohs Scale.

Ask the students to re-read the text and identify three mechanical properties (hardness, cleavage, tenacity). Then ask them what the other properties are: magnetic (not all minerals), transparency and density.

Students should now do questions 12 to 14.

Tips: For question 12, ask the students to look at the scale in pairs, and to decide not only what it is measuring but why this would be useful: Brainstorm ideas on the board. For question 13, do this activity quickly with the whole class, then ask students to think of other quiz-type questions to identify another property.

For question 14, play the audio at least twice. The second time, stop after each sentence and elicit the answer.

Now ask students to do questions 15 and 16. They can do this as homework, or if they access to reference material (digital or otherwise), they could do it in class. Ask them to discuss their findings before handing in their report.

2.2. The importance of mineralsOnce students internalise the definition and the properties of minerals, it should be easier for them to understand their importance and the sustainable management of mineral resources.

Video: A DAY WITHOUT MINERALS

This video shows some daily objects that are manufactured with minerals. After watching the video twice, ask the students to answer the questions given in the worksheet. To finish the activity, ask students: What do we use minerals for nowadays?

Finish the section revising the Key concepts at the end of the section and also remind them about the Final task that they should do about the environmental impact of mineral extraction.

Curricular adaptation: 3. PROPERTIES OF MINERALS


Answer key

Remember

12. Explain in your own words what the Mohs scale is? What is it used for?

It is a scale that measures the hardness of minerals. Hardness is not a quantitative property so that is the reason the Mohs scale is so useful to classify minerals and their uses.


3 +www


3

2.1.2. Mechanical properties

❚ Hardness describes a mineral’s resistance to scratching. To check if a mineral is harder than another, we can scratch one with the other. The mineral that is scratched is softer than the mineral that scratches it.

We can use minerals that are listed on the Mohs scale to identify hardness. This scale grades the hardness of 10 minerals from 1 to 10. The softest mineral, Talc (1) can be scratched by all the others. At the other end of the scale, diamond (10) can scratch all the other minerals and can only be scratched by another diamond.

❚ Cleavage describes the way a mineral breaks. Many minerals break to show flat surfaces, maintaining the crystalline structure. For example, galena breaks into cubic shapes and gypsum breaks into sheets.

❚ Tenacity describes how easily a mineral breaks. A fragile mineral breaks easily, such as talc.

Some minerals can be pulled into thin threads. This is the case of copper threads that conduct electricity. This is called ductile tenacity.

2.1.3. Magnetic properties

Some minerals, such as magnetite, behave like a magnet. They attract objects that contain iron and nickel.

2.1.4. Other properties of materials

❚ Transparency describes how a mineral reacts to light. A mineral can be transparent, such as diamond, when light can pass through it; translucent, like quartz, when light passes through it but is distorted; or opaque, like galena, when no light can pass through.

❚ Density is the relation between the mass and volume of a mineral (density = mass/volume). Density is usually measured in grams per cubic centimetre (g/cm3). This property is specific to each mineral and is independent of size. So, the density of a mineral is important information for identifying minerals.

Gypsum

Magnetite

2.2. The importance of minerals

Throughout history, the ability to identify minerals and to obtain raw materials has been essential to the success of civilizations.

Today, minerals are used mainly as metal ores, as raw materials for industry, or sold as gems or precious stones.

2.2.1. Metal ores

These are minerals that metals are extracted from (see table on the right). Other minerals known as native or noble minerals are found in nature in their pure state. Examples of these minerals are gold, silver or platinum, admired since ancient times for their colour, beauty, easiness to mould and durability.

2.2.2. Raw materials for industry

These are the most abundant minerals found in the Earth’ s crust. Some examples are: uraninite which provides us with uranium used as fuel in nuclear power stations; quartz, which is very important for manufacturing glass, computer components, parts and solar panels; and gypsum, which is used for manufacturing plaster, alabaster, fertilisers and explosives.

2.2.3. Gems or precious stones

These are beautiful and rare minerals which have a great economic value. They are used for jewellery, usually after a process of cutting and polishing to bring out their lustre. Some of the most well-known gems are diamonds, rubies, sapphires and emeralds.

2.3. Sustainable management of mineral resources

Uncontrolled mining has an impact on the environment such as contamination of water and land contamination with metals. It can also cause health problems for miners: headaches, blood poisoning with lead and mercury, and breathing problems.

Responsible use of minerals is essential to avoid or reduce this negative impact. We can help by recycling minerals and electronic devices made with minerals such as mobile phones and computers.

Diamond Ruby Sapphire Emerald

Main ores of some metals

Ore Metal

Bauxite Aluminium

Blende Zinc

Chalcopyrite Tin

Cinnabar Mercury

Galena Lead

Hematite Iron

Key concepts

❚ Minerals are solid, inorganic substances of natural origin. They have a definite chemical composition and most have a crystalline structure.

❚ They have properties that allow us to identify them such as hardness, lustre, streak or density.

❚ They are used as metal ores, as raw materials for industry and as gems or precious stones.

Mohs scale

Hardness Mineral Characteristics

1 Talc Very soft, because it can be scratched by another mineral.2 Gypsum

3 CalciteSoft minerals that can be scratched by the point of a knife.

4 Fluorite

5 Apatite

6 Orthoclase Hard minerals. Orthoclase can be scratched with sandpaper and quartz scratches glass.7 Quartz

8 TopazVery hard, cannot be scratched by any other mineral.

9 Corundum

10 Diamond

Galena

Quartz

The mechanical properties of minerals refer to how the mineral behaves when a force is applied to its surface.

Understand

12. Explain in your own words what the Mohs scale is? What is it used for?

13. A crystal is hit and breaks into small cubes. What property does this describe?

Analyse

14. Listen and say which mineral properties are being described.

Analyse

15. Find out about the use of the metals extracted from these mineral ores: bauxite and cinnabar. Write a short report in your notebook.

16. Find out about the hardness of the gems in the photos above. Do you think their economic value is related to their hardness? Explain your answer.


111

3The Geosphere

13. A crystal is hit and breaks into small cubes. What property does this describe?

In this case, we are talking about cleavage, because it keep the crystal shape. To be precise, we call it cubic cleavage.

14. Listen and say which mineral properties are being described.

Audio script and answers:

a) This is how easily a mineral breaks. (tenacity)

b) This is the relation between mass and volume.(density)

c) This is the way a mineral breaks.(cleavage)

d) This is how a mineral reacts to light.(transparency)

Analyse

15. Find out about the use of metals extracted from these mineral ores: bauxite and cinnabar. Write a short report in your notebook.

Metals extracted from these minerals are, in the following order: aluminium, mercury and zinc. Aluminium and zinc are very useful to produce metal tools and utensils. Mercury is used to make thermometers because of its high capacity of dilation.

16. Find out about the hardness of the gems in the photos above. Do you think their economic value is related to their hardness? Explain your answer.

Diamond Ruby Sapphire Emerald

The hardness of these gems or precious stones are equal or superior to 8. Their economic value is related to their colour, brightness, natural beauty and also their hardness and durability over time.


3 The Geosphere

112

3. RocksStart this section by showing the different types of rocks. This is a good opportunity to review the differences between rocks and minerals just to make sure all the students understood these concepts. Students can look for the variations between the different types of rocks. To help them you could use the following chart by copying it on the board and filling it in with the whole class:

Rock Density Visible sediments

Visible minerals

Aligned minerals

Ask students about the concepts of composition and texture of rocks. You can add two more columns to the chart (one for composition and one for texture) and students should copy it in their notebook and complete it as they work through the unit.

The practical activity about The texture of rocks on page 64 will help students to clearly understand these concepts.

There are many ways of classifying rocks, but geologists prefer to classify them according to their origin. Rocks can be metamorphic, igneous or sedimentary.

Now students could de questions 17 to 20.

Tips: Before doing question 17, check that students understand the meaning of homogeneous and heterogeneous in other contexts. For question 18, play the audio at least twice. The second time, stop after each sentence and elicit the answer. For question 19, ask students to do this in pairs.

Curricular adaptation: 4. ROCKS


3.1. Igneous or magmatic rocksIgneous or magmatic rocks are the ones that originated from the solid magma, in the interior or the exterior of the crust. At this point, you can highlight the difference between magma and lava. Magma is formed in the Earth’s interior while the lava is in the Earth’s exterior.

Now students can do question 20. Ask students to do this in-dividually, and then write various answers on the board ( some incorrect), then ask the students in groups to choose the correct answers.

Curricular adaptation: 5. TYPES OF ROCKS


Answer key

Understand

17. Explain the difference between homogeneous and heterogeneous rocks. Why are coal and petroleum exceptions?

Homogeneous rocks only have one mineral, for example, limestone that is composed only of calcite. On the other


3 +www


3

3. ROCKS

Rocks, like minerals, have properties that allow us to identify them, for example, composition and texture.

❚ The composition of a rock refers to the minerals that make up the rock. Some rocks only have one mineral. For example, limestone is composed only of calcite. These rocks are called simple or homogeneous rocks. Others are made up of a variety of minerals. For example, granite is made up of quartz, feldspar and mica. These rocks are called complex or heterogeneous rocks.

There are exceptions such as petroleum and coal, which are not of mineral origin as they come from animal remains and so do not contain minerals.

❚ Texture refers to the size and arrangement of the minerals in the rock. It is not always possible to observe the texture of a rock without using a magnifying glass or even a microscope.

These instruments allow us to identify the minerals that make up rocks. For example, without a magnifying glass granite appears to have different colours: greys, whites and blacks. With a magnifying glass we can see that it is made up of crystals of quartz (greys), feldspar (whites) and mica (blacks).

There are many ways of classifying rocks, but geologists prefer to classify them according to their origin. Rocks can be metamorphic, igneous or sedimentary.

3.1. Igneous rocks

In some areas of the upper mantle, minerals melt due to high temperatures.

When magma rises to the surface it can remain in the crust or it can exit to the exterior. In both cases, away from the source of heat, magma cools until it becomes solid and forms igneous rocks or magmatic rocks.

These rocks are made up of one or several minerals compressed together, so they are extremely compact. The resistance of igneous rocks to pressure makes them a perfect material to construct buildings.

Igneous rocks are classified as volcanic or plutonic depending on where they were formed.

❚ Volcanic igneous rocks or extrusive rocks are formed when magma rises and leaves the Earth’ s crust as lava. Lava cools quickly and forms volcanic rocks.

❚ Plutonic igneous rocks or intrusive rocks are formed when rising magma cools slowly inside the Earth’ s crust. The mineral crystals are easily visible as they had more time to form.

Rocks are natural aggregates made up of one or various different minerals.

Magma is a substance made up of melted materials mixed with gases and water, formed in the Earth’ s interior.

Conglomerate

Types of rocks

Formed by the transformation of other rocks subjected to high

pressure conditions and/or temperatures, without reaching a

melting state.

Sediments are fragments of other rocks, minerals and

organic remains. Sedimentary rocks

form when sediments consolidate.

These originate when magma from the

Earth’ s interior cools and solidifi es.

Sedimentary MetamorphicIgneous

Obsidian is shiny black and originates in the continental crust. It has a glassy texture. The crystals have not had time to form.

Pumice or pumice stone is a continental rock. It is easily recognised because of the many small holes in the surface. These were formed by gases that were in the rock before it solidified.

Basalt originates in submarine volcanoes. It contains very small minerals due to its rapid cooling. It is the most abundant rock found in the Canary Islands and the ocean floor.

Granite is the most abundant plutonic rock on the continental crust.

Syenite is a continental plutonic rock.

Gabbro is a plutonic rock found in the ocean’s crust.

Composition and texture of granite

quartz

mica

feldspar

Understand

17. Explain the difference between homogeneous and heterogeneous rocks. Why are coal and petroleum exceptions?

18. Listen and identify the rocks: igneous, sedimentary or metamorphic.

Analyse

19. Study the photo. What type of rock is a conglomerate? Is it homogeneous or heterogeneous? Explain your answer.

Understand

20. Explain why crystals in the minerals that make up plutonic rocks are visible, but are not visible in the minerals of volcanic rocks.


113

3The Geosphere

hand, heterogeneous rocks are made up of a variety on minerals. For example, granite is made up of quartz, feldspar and mica. Coal and petroleum are exceptions because they are not of mineral origin.

18. Listen and identify the rocks: igneous, sedimentary or metamorphic.

Audio script and answers:

a) These are formed when rocks are subjected to high pressure conditions. (metamorphic)

b) These originate when the magma cools. (igneous)

c) These form when sediments consolidate. (sedimentary)

Analyse

19. Study the photo. What type of rock is a conglomerate? Is it homogeneous or heterogeneous? Explain your answer.

A conglomerate is a sedimentary rock that is clearly visible. It is made up of other rocks as well as sediments. Fragments of a heterogeneous rock are visible and distinguishable with the naked eye.

Understand

20. Explain why crystals in the minerals that make up plutonic rocks are visible, but are not visible in the volcanic rocks?

Because plutonic rocks are formed during a very slow process so mineral crystals have more time to form. On the other hand, volcanic rocks are formed when magma rises and leaves the Earth’s crust as lava. And lava cools quickly so there is no time for the crystallisation.


3 The Geosphere

114

3.2. Sedimentary rocksBefore starting with sedimentary rocks, clarify the definition of sediments, sedimentary basins and diagenesis.

Ask students How do sediments transform into sedimentary rocks?

Explain the origin of sediments from the erosion of rocks by geological agents, and the posterior transportation and sedimentation. The illustration on page 56 will visually help students to understand this process. Once they understand the formation of sedimentary rocks, you can carry on explaining the processes that could happen in the diagenesis: the compaction and the cementation.

Reading comprehension: THE ROCK OF AGES

This text is about how slow the geological processes happen. Stu-dents will realise how much implicated are human beings in these processes since millions of years while the sand transformation in rock is still happening.

3.2.1. Formation of sedimentary rocksAsk students to read section 3.2.1 and then close their books. Read out the process for either compaction or cementation and ask them to stand up if you defined one or the other.

Students could now do questions 21 and 22. For question 21, ask students to work on this problem in pairs. For question 22, they should re-read section 3.2.1 first and then answer the question.

3.2.2. The classification of sedimentary rocksTell students to read the text and to look at the different rocks. Ask them: What is the difference between detrital and non-detrital sedimentary rocks? When talking about detrital sedimentary rocks, highlight the peculiarities of coal and petroleum as combustible fossils.

These sedimentary rocks originate from the remains of living things that have not decomposed. They can burn and produce energy.

Coal could be from different types according to their calorific value. From the least to the most calorific, they are classified in peat, lignite, coal and anthracite. The calorific value depends on the quantity of coal: more coal, more powerful.

Answer key

Analyse

21. 2.5 cm of sediments are accumulated every 10 years in a sedimentary basin. After the process of compaction, will the volume of sediment be thicker or thinner? Explain your answer.

The thickness will be 0.25 cm every 10 years.

22. Explain why water is important in the formation of sedimentary rocks.

Because sediments, before transforming into sedimentary rocks, must lose water by compaction or cementation.


3 +www


3

3.2. Sedimentary rocks

Rocks found on the Earth’ s surface are changed by the action of the wind, sea, rivers, rain or ice. The elements wear down rocks in a process of erosion. The rock fragments are deposited in the lowest areas of the Earth’ s surface.

3.2.1. Formation of sedimentary rocks

Sediments deposited in sedimentary basins (1) often follow two essential processes for the formation of sedimentary rocks:

❚ Compaction (2) is when sediments lose volume. Due to the weight of the sediments on top, water is lost and the sediments become compacted.

❚ Cementation (3) takes place after the water is lost and the salts form crystals. The crystals act like cement and stick the sediments together to form sedimentary rocks.

3.2.2. Classification of sedimentary rocks

These rocks are classified by looking at the origin of the sediments that compose them. Sedimentary rocks can be detrital or non-detrital.

❚ Detrital sedimentary rocks are made up of other rocks. Depending on the size of the fragments or grains that compose them, we can distinguish various types.

❚ Non-detrital sedimentary rocks are not made up of fragments of other rocks. They are made up of sediments from skeletons of marine life or mineral salts. They can also come from the remains of living things that have not decomposed.

❚ Sediments are fragments of rock and organic material that have been transported and deposited by water and wind.

❚ The places where sediments are deposited are called sedimentary basins.

The process in which sediments transform into sedimentary rocks is called diagenesis or lithification.

Conglomerates contain grains that are more than 2 mm big, called clasts. Clasts are joined together by smaller grains.

Sandstone contains grains smaller than 2 mm that are easily visible. It feels rough to the touch.

Clay is made up of very small grains that can only be observed with a magnifying glass or a microscope. It is soft to the touch.

Limestone can contain fossil remains or be composed of mineral salts. It produces effervescence in contact with acids.

Gypsum is a rock composed of the mineral of the same name, gypsum. It originates from the salts of water evaporation in shallow2 lakes and seas.

Coal forms from the accumulation and decomposition of plant remains over millions of years.

Petroleum also results from the transformation of organic remains. It is considered a rock even though it is not in a solid, but liquid state.

Sedimentary basins: the origin of sedimentary rocks

Formation of sedimentary rock

Coal and petroleum originate from the remains of living things that have not decomposed. They can burn and produce energy. This is why they are called combustible fossils. Coal originates from plant remains that could not decompose completely because they were buried in sediments and sand. Petroleum is the result of the transformation of remains of marine microorganisms buried in the ocean floor.

Analyse

21. 2.5 cm of sediments are accumulated every 10 years in a sedimentary basin. After the process of compaction, will the volume of sediment be thicker or thinner? Explain your answer.

22. Explain why water is important in the formation of sedimentary rocks.

Analyse

23. Can you explain why limestone, which contains remains of living things, cannot be burned like coal or petroleum?

2 shallow: not deep


115

3The Geosphere

Analyse

23. Can you explain why limestone, which contains remains of living things, cannot be burned like coal or petroleum?

Because fossil remains in limestone are fossilized and consequently they lose their organic part and just have left hard parts like carapaces, shells, etc.


3 The Geosphere

116

3.3. Metamorphic rocksMetamorphic rocks originate from the transformation of other rocks because of the increased pressure, high temperature or both. Those factors act on the rocks that are placed in the interior of the Earth and provoke a reshaping or a change in the composition of rocks, changing them into a different type of rock.

To become a metamorphic rock, the rock cannot melt before its formation. If the original rock melts, magma will form. Magma can rise and cool under the crust, creating plutonic igneous rocks. Magma can also come out of the crust to the exterior and solidify, creating volcanic igneous rocks.

When you finish this section, it is important to highlight that rocks are variable and are constantly changing, either because of external agents or pressure increase or high temperatures. It causes a slow but constant transformation on the rocks called the rock cycle.

Students could now do question 24. Before answering, they need to review the section on igneous rocks in order to complete the task.

The science practical suggested on page 64 will clarify concepts of this section.

Web page: IDENTIFYING ROCKS

Short quiz to finish this section. There are different questions about a photo. Students could make an identification key from the questions and answers of the identified rocks.

3.4. The rock cycle

Ask students: How can rocks change into something different?

Tell them to read the text, look at the image and discuss the process involved in rock transformation in pairs. Ask them: Can a metamorphic rock change directly into an igneous rock? For a rock to be metamorphic, does it have to be a sedimentary rock first?

Ask the students to close their books and then ask them to help you draw the rock cycle on the board, step by step. Give cues when necessary. The ask them to copy their own versions in their notebooks.

Students could now do questions 25 to 27. For question 25, pPlay the audio twice, the second time ask students to raise their hands if they think the sentence is true. Before doing question 26 they should look at the diagram of the rock cycle once again. For question 27, ask students to discuss this in small groups and to come up with three simple explanations.

Finish this section reviewing the Key concepts on page 59.

Curricular adaptation: 6. THE ROCK CYCLE



3 +www


3

3.3. Metamorphic rocks

Rocks that are located deep in the crust are subjected to the pressure created by the rocks above them. In addition, if these rocks are near magma, they are also exposed to high temperatures. Pressure and high temperature causes changes in the minerals that compose a rock and a new rock forms.

Metamorphic rocks are classified according to their texture, in two groups: foliated and non-foliated.

❚ In foliated metamorphic rocks the minerals are arranged to form parallel layers. This layered structure is easily observed in many rocks of this type.

Foliated metamorphic rocks are identified from low to high grades of metamorphism: slate, schist, gneiss and migmatite.

❚ In non-foliated metamorphic rocks the minerals are not arranged in layers. The most common are marble and quartzite.

3.4. The rock cycle

Any rock can be transformed into a different type of rock.

These processes occur very slowly, so the rock cycle takes place over millions of years.

Key concepts

❚ Rocks are aggregates of two or various minerals.

❚ According to their origin, rocks are classified into igneous or magmatic, sedimentary, and metamorphic.

❚ The process by which rocks transform into different rocks is called the rock cycle.

The rock cycle is a series of processes that a rock goes through to transform into another type of rock.

Slate results from the metamorphism of clay. It is composed of small crystals visible under the microscope. Slate breaks into thin sheets.

Schist comes from clay, after a higher metamorphism than in the case of slate. Its crystals are visible without a microscope.

Gneiss originates from detrital sedimentary rocks or from granite. Its crystals are bigger than those in schist. They are arranged in wavy bands.

Migmatite are rocks half way between igneous and metamorphic rocks. They have experienced a very intense metamorphism that partially melts the original rock.

Marble originates from the metamorphism of limestone. Its minerals are transformed due to exposure to high temperatures.

Quartzite originates from the metamorphism of sandstone. Like marble, it forms due to the exposure of the original rock to high temperatures.

The rock cycle

❚ Metamorphism is the process that changes a rock into a different type of rock.

❚ Rocks that form in this way are called metamorphic rocks.

Analyse

24. Compare the igneous and metamorphic rock processes. What conditions are needed for a rock to transform into metamorphic rock and not igneous when subjected to high temperatures?

Understand

25. Listen, look at the rock cycle and say true or false.

26. In which layer of the geosphere does the rock cycle take place? Which rocks form at the deepest level?

Analyse

27. Explain which types of rocks can transform into igneous rocks.

All rocks, exposed to the action of wind and water, can go undergo the processes of erosion, transportation and sedimentation. Sediments deposited in sedimentary basins undergo the process of diagenesis or lithification and are transformed into sedimentary rocks.

The rocks in the Earth’ s crust are subjected to high pressures and/or temperatures form metamorphic rocks. If the rocks melt, magma will form. Magma can rise and cool under the crust, creating plutonic igneous rocks. Magma can also come out of the crust to the exterior and solidify, creating volcanic igneous rocks.


117

3The Geosphere

Answer key

Analyse

24. Compare the igneous and metamorphic rock processes. What conditions are needed for a rock to transform into metamorphic rock and not igneous when subjected to high temperatures?

Igneous rocks are formed when magma (melted minerals) rises to the surface, and as it cools it becomes solid. Metamorphic rocks are rocks that change into a different type of rock when exposed to pressure and high temperature.

Understand

25. Listen, look at the rock cycle and say true or false.

Audio script and answer: a) The rock cycle is a series of processes that a rock goes

through. (True) b) The processes happen very quickly. (False) c) Not all rocks can undergo the processes. (False) d) If the rocks melt, magma will form. (True)

26. In which layer of the geosphere does the rock cycle take place? Which rocks form at the deepest level?

In the Earth’s crust, the most superficial layer, where materials are solidified, thus forming rocks. At the deepest level, we find plutonic igneous rocks and metamorphic rocks because those depend on high pressure and high temperature, very common in deepest areas.

Analyse

27. Explain which types of rock can transform into igneous rocks.

An igneous rock or magmatic rock can transform into any types of rocks:

– Sedimentary rock: if it is subjected to the following agents of the external geological processes: weathering, erosion, transportation, sedimentation or deposit of those fragments and diagenesis or transformation in a sedimentary rock.

– Magmatic rock: if it is subjected to high temperatures that provoke a fusion and again another transformation into magma. When magma solidifies, a new igneous rock is formed.

– Metamorphic rock: if it is subjected to high pressure/temperature (metamorphism), without melting it but transforming it into a different rock.


3 The Geosphere

118

4. The use of rocksAsk the students: What objects can you see around you that are made of rocks? Probably they will find objects related to building. However, rocks are useful in the majority of objects around us, from building to technological ones.

Read the following sentences just to review some types of rocks that will be useful during the lesson:

❚ Granite and basalt are igneous or magmatic rocks.

❚ Limestone, clay, coal and petroleum are sedimentary rocks.

❚ Marble and slate are metamorphic rocks.

Human beings have been using rocks since the Palaeolithic Age. At the beginning their use was natural, such as refuges (caves or caverns) or utensils for hunting. Nowadays, the main use of rocks is for building, ornamentation, and as a source of fuels and technological materials. In the latter, they do not use rocks directly to produce them, but rather minerals extracted from them like aluminum, which is obtained from bauxite.

Now, students should do questions 28 to 30. 28. Ask students to do this in their notebooks and then compare with another stu-dent. 29. Do this as a whole class activity, eliciting the answer. 30. Write different possibilities on the board and then ask students to choose the most appropriate answer for each.

Review concepts learnt in this section by reading the Key concepts on page 60.

Curricular adaptation: 7. THE USE OF ROCKS


5. Extraction of minerals and rocksThis section could make students think about the importance of sustainable management of mineral and rock resources. It is es-sential to know the consequences of the uncontrolled use of tho-se resources, both for the environment and for people.

It is important that students become aware of the need for sear-ching for alternatives to use and overuse of non-renewable re-sources as well as their consequences. Sustainable use of mineral and rock resources allow better work conditions for millions of people and also avoid unnecessary risks. Now students do ques-tions 31 and 32.

Tips: 31. Ask students to look at the different definitions of ex-traction and the image. 32. Elicit different answers from the class.

Web page: THE PROCESS OF GOLD EXTRACTION AND ITS USE

To finish this section, students could watch this video. It is about the extraction of gold and its importance to humans. After watching the video, answer the questions on the worksheet.

Curricular adaptation: 8. MINERAL AND ROCK EXTRACTION



3 +www

4. THE USE OF ROCKS

The evolution of humans since the Palaeolithic Age has been linked to the use of rocks for building, ornamentation or making utensils for hunting. Today, we continue to use rocks for these activities.

The main uses of rocks are building, ornamentation and as a source of fuels and technological materials.

❚ Building materials: some rocks are used directly. Others are modified for building purposes.

Cement, concrete, ceramics and glass are some of most commonly used building materials. They all come from rocks.

5. EXTRACTION OF MINERALS AND ROCKS

Rocks and minerals are extracted from mineral deposits in the Earth’ s crust.

The minerals that are of interest to extract are called ore deposit. The other rocks and minerals are referred to as gangue.

To locate a deposit drill holes are made with large drills. Cylinders of earth are extracted and then analysed.

Depending on how deep a deposit is and its accessibility, the extraction can be superficial or subterranean.

❚ Superficial extractions: rocks and minerals are extracted from the surface or not very deep under the surface. This type of extraction has a great impact on the environment. There are various types:

• In opencast mines, such as those in Riotinto (Huelva), the minerals are not deep underground. To extract them, they make funnel-shaped holes (pits). The edges are stepped to transport the minerals to the surface.

• In quarries, large rocks are extracted, cut into blocks or slabs. An example are the marble quarries in Macael (Almería).

• Gravel4 is extracted from gravel pits. These are usually found in or near large riverbeds. There are many in the Tajo river basin.

❚ Subterranean extractions: rocks and minerals are located deep within the crust and are extracted using underground mines. Vertical tunnels called shafts are constructed and horizontal tunnels or galleries called adits, to extract the minerals.

Key concepts

❚ A deposit is the place where minerals or rocks are extracted.

❚ Extractions are classified according to depth: superficial or subterranean.

A deposit is the place where minerals or rocks are found in sufficient quantity to make extraction economically beneficial.

Key concepts

❚ Rocks are used, directly or modified, as building materials.

❚ Rocks also have ornamental uses, as fossil fuels or as a source of minerals for technological use.

Cement is obtained by grinding and heating limestone and clay. It is mixed with water to create a substance that hardens3 when dry. It allows us to stick rocks together.

Concrete is created by mixing cement, water, sand and gravel. When dry, it is harder and stronger than cement. This is why it is used for pillars and foundations.

Ceramics are made with pulverised clay mixed with water, modelled and cooked at high temperatures. They are used to make bricks, tiles or dishes.

Glass is created from quartz present in sand. Sand is placed in an oven at a high temperature and it melts. When cooled, glass can be shaped in different ways.

3 harden: to become hard

Extraction of rocks

Understand

31. What type of superficial extraction is shown in the picture?

❚ Ornamental rocks: marble, granite, slate and basalt are often used in decoration. Due to their beauty once they have been carved and polished, these rocks are used in sculptures, floors of buildings and many other decorative elements in the interior and exterior of buildings.

❚ Source of fossil fuels: sedimentary rocks such as coal and oil are used because they produce a lot of when burnt.

❚ Source of minerals for technological use: rocks rich in quartz are a source of silicon, which is used to make computer processors or photovoltaic solar panels. Aluminium, obtained from a sedimentary rock called bauxite, is used to make many objects such as planes, soft drink cans or kitchen utensils.

Remember

28. Make a table of rocks used to make building materials. Include what materials they are used to make and the uses of those materials.

29. Which types of rocks are usually used for decoration?

Understand

30. Explain the difference between concrete and cement.

Understand

32. Explain in your own words, the difference between a subterranean mine and a quarry.

4 gravel: a mixture of rock fragments between 2 and 64 mm


119

3The Geosphere

Answer key

Remember

28. Make a table of rocks used to make building materials. Include what materials they are used to make and the uses of those materials.

Rocks Materials Uses

Cement Limestone and clay Stick rocks together

Concrete Cement, water, sand and gravel

Build pillars and foundations

Ceramics Pulverised clay mixed with water

Make bricks, tiles or dishes

Glass Quartz present in sand

Make windows, bottles, glasses

29. Which types of rocks are usually used for decoration?

Plutonic rocks because of their beauty once they have been cut and polished.

Understand

30. Explain the difference between concrete and cement.

Cement is made from grinding and heating limestone and clay. Concrete is created by mixing cement, water, sand and gravel. When dry, it is harder and stronger than cement. This is why it is used for pillars and foundations.

Understand

31. What type of superficial extraction is shown in the picture?

It is an opencast mine, they are making a funnel-shaped hole (piles) to extract.

32. Explain in your own words the difference between a subterranean mine and a quarry.

In subterranean mines, vertical tunnels called shafts and horizontal tunnels or galleries are constructed to extract the minerals while in quarries, minerals are extracted from the surface or not very deep under the surface and it has a great impact on the environment. Large rocks are extracted and cut into blocks or slabs.


3 The Geosphere

120

The Earth: origin and composition

33. Find out the thickness of the different layers of the Earth and order them from thickest to thinnest.

Crust: between 6 and 70 km thick

Upper mantle: up to 670 km deep; around 600 km thick

Lower mantle: up to 2900 km deep; around 2230 km thick

Outer core: up to 5120 km deep; around 2220 km thick

Inner core: up to 6370 km deep; around 1250 km thick

In order from the thickest to the thinnest: lower mantle-outer core-inner core-upper mantle-crust

34. Make a table to compare the characteristics of the continental crust and the oceanic crust.

Characteristics Continental Crust Ocean Crust

The age of materials that formed it

More than 1 000 million years old

200 million years old

Thickness Between 10 and 70 km Between 6 and 10 km

Rocks that formed it Granite, clay and slate Basaltic rockSuperficial reliefs that composed it

Continental platform, continent and islands

Sea floor

35. Were all materials distributed according to their density from the very beginning? Explain your answer.

No, the density differentiation happened after the process called accretion of planetesimals.

36. Explain why the following statements are true or false.

a) The seismic method only allows us to know the composition of the Earth’s crust. False, it allows us to know the composition and the structure of the Earth’s interior.

b) The Earth is made up of solid materials. False, it is made up of solid materials and molten rocks like in the upper mantle and in the outer core.

c) The Earth’s crust has a uniform thickness of 50 km. False, the thickness is variable in the Earth’s crust, for example, the continental crust is thicker than the oceanic crust.

d) Denser materials in the geosphere are found on the Earth’s surface. False, in the geosphere the densest materials are found in the inner core and the lightest ones in the crust.

e) The Earth’s mantle is located between the Mohorovicic discontinuity and the Lehmann discontinuity. False because the Earth’s mantle is located between the Mohorovicic discontinuity and the Gutenberg discontinuity.

f) The Earth’s inner core is solid because the temperature is lower than in the outer core. False, the inner core is solid although its temperature is colder than in the outer core, because the pressure is higher.


3 +www

62 63

The Earth: origin and composition

33. Find out the thicknesses of the different layers of the Earth and order them from thickest to thinnest.

34. Make a table to compare the characteristics of the continental crust and the oceanic crust.

35. Were all materials distributed according to their density from the very beginning? Explain your answer.

36. Explain why the following statements are true or false.

a) The seismic method only allows us to know the composition of the Earth’ s crust.

b) The Earth is made up of solid materials.

c) The Earth’ s crust has a uniform thickness of 50 km.

d) Denser materials in the geosphere are found on the Earth’ s surface.

e) The Earth’ s mantle is located between the Mohorovičić discontinuity and the Lehmann discontinuity.

f) The Earth’ s inner core is solid because the temperature is lower than in the outer core.

37. The following graph shows how seismic waves move around the planet. Which seismic wave is travelling at a higher speed? Which layers of the Earth do they go through?

Minerals

38. Which property of materials does the image show?

The use of rocks

53. Explain which rocks provide the following building materials:

54. Why are coal and petroleum referred to as fossil fuels?

55. What is sandpaper? Explain why it is not made of fragments of gypsum or talc.

56. Copy and complete the table in your notebook for the following rocks: petroleum, chalk, limestone, clay and coal.

57. Research how concrete and bricks are made. Make a diagram.

Extraction of minerals and rocks

58. Complete the sentences in your notebook.a) The rocks extracted from ….. are cut into blocks.

b) ….. are horizontal tunnels in underground mines.

c) ….. is sediment that is usually extracted in or near large riverbeds.

59. Explain the meaning of the terms deposit and mine.

39. Describe four properties of minerals.

40. Explain if an ice cube and coral used in jewellery are minerals or not.

41. Investigate and then copy and complete the table in your notebook.

42. According to the Mohs scale, what is the hardness of a mineral that scratches orthoclase but is scratched by quartz?

43. Explain how can you distinguish white quartz from orthoclase which is the same colour?

44. Find out why the colour and streak of a mineral isn’t always the same.

45. Find out why pyrite is also referred to as ‘fool’s gold’.

Rocks

46. Explain the three characteristics that are used to classify rocks.

47. Pumice is a rock that floats in water. Why do you think this is? Is it a natural or an artificial rock? Justify your answer.

48. Copy the following terms in two columns in your notebook and then match them.A: limestone, granite, clay, marble, basalt, chalk, detrital

sedimentary

B: non-detrital sedimentary, plutonic, volcanic, foliated metamorphic, non-foliated metamorphic

49. Are there any rocks which are not composed of minerals? What type of rocks are they?

50. When 1 kg of granite was analysed in the laboratory using different chemical processes they obtained 250 g of a white mineral, 300 g of another mineral, almost black, and the rest was a grey mineral.a) What is the name of each mineral that composes granite?

b) Which mineral corresponds to the grams of minerals above?

51. On an excursion, Ana found a rock that contained a plant fossil that lived on Earth millions of years ago. What type of rock do you think it was? Explain your answer.

52. Which rock forms quartzite after metamorphism? What size are the grains of the original rock?

60. Find out what a slag heap is. What environmental problems do they cause?

61. Discuss this statement: ‘New generation mobile telephones are made of stone’.

Spee

d of

sie

smic

wav

e (k

m/s

)

Depth (km)

0

Moho Gutenberg Lehmann

Waves S

MantleOuter core

Inner core

Waves P

0

3

6

9

12

1 000 2 000 3 000 4 000 5 000 6 000

Rock Use Objects created with it

... ... ...

a) glass c) cement e) brick

b) concrete d) lime f) tile

STUDY SKILLS

❚ Create your own summary of the unit using the Key concepts. Add any other important information.

❚ Copy the following diagram in your notebook and add the missing information to create a conceptual map of the unit.

Slow but sure

In Chihuahua, Mexico, giant crystals were found in the cave of Naica. They are mega-crystals of selenite (a variety of gypsum). For years, the Spanish investigator Juan Manuel García has been studying how fast they grow. Thanks to a special microscope designed by Japanese engineers, we now know that these formations grow at the equivalent of one hair every 100 years. However, their growth has stopped in recent years due to mining activities, to extract minerals from the underground water that the minerals need to grow.

EVA VAN DEN BERG

National Geographic, November 2011(Translated and adapted)

a) What is the text about?

b) Can you explain the title?

c) Why have the crystals stopped growing?

d) Do you think the growth of these formations can be observed by any person?

e) Find out about selenite. Explain why water is essential for its formation.

READ AND UNDERSTAND SCIENCE

You can record your summary and listen to it as many times as you like to revise.

3

Mineral Ore

Cassiterite ...

... Lead

Hematite ...

... Zinc

Chalcopyrite ...

❚ Create your own scientific glossary. Define the following terms: quarry, clast, sedimentary basin, deposit, discontinuity, reef, phytoplankton, fossil, gallery, gangue, geosphere, gravel, magma, metamorphism, mineral, ore, rock, sediment, seismic wave. Add any other terms you consider important.

The geosphere

layers

is divided in is composed of

minerals rocks

are classifi ed byare classifi ed by

......

...

+www

CONSOLIDATION

CONSOLIDATION


121

3The Geosphere

37. The following graph shows how seismic waves move around the planet. Which seismic wave is traveling at a higher speed? Which layers of the Earth do they go through?

Spee

d of

sie

smic

wav

e (k

m/s

)

Depth (km)

0

Moho Gutenberg Lehmann

Waves S

MantleOuter core

Inner core

Waves P

0

3

6

9

12

1 000 2 000 3 000 4 000 5 000 6 000

P waves are traveling at a higher speed.

P waves go through all layers of the Earth’s interior, while S waves only go through the crust and the mantle.

Minerals

38. Which property of materials does the image show?

Tenacity and resistance, that shows when a mineral breaks.

39. Describe four properties of minerals.

Open answer. Students could choose four of the several properties of minerals mentioned in the unit.

40. Explain if an ice cube and coral used in jewelry are minerals or not.

An ice cube is not a mineral because it is made up by a human being when freezing water and giving it an artificial geometrical shape. On the other hand, the natural ice is considered a mineral.

The coral used in jewelry is not a mineral because it is not inorganic, it is formed by an animal called coral.

41. Investigate and then copy and complete the table in your notebook.

Ore Metal

Bauxite Aluminium

Blend Zinc

Chalcopyrite Copper

Cassiterite Tin

Cinnabar Mercury

Galenite Lead

Hematite Iron

42. According to the Mohs scale, what is the hardness of a mineral that scratches orthoclase but is scratched by quartz?

The hardness will be between 6 to 7 according to the Mohs scale.

43. Explain how you can distinguish white quartz from orthoclase which is the same colour.

We can distinguish them by other characteristics or properties, like the streak or the lustre. The streak in the quartz is always white. In case there are a fragment of quartz and another one of orthoclase, you can compare their hardness as the quartz scratch the orthoclase, but not the other way round.

44. Find out why the color and streak of a mineral isn’t always the same.

Because the colour of the streak or the powder produced when a mineral is scratched is actually its ‘original colour’, according to its chemical composition and its crystalline structure. The colour of a mineral could have been influenced by external factors and caused a variation on its original colour.

45. Find out why pyrite is also referred to as ‘fool’ s gold’.

Because its appearance (colour and lustre) is similar to the gold, but its commercial value is much cheaper. Historically, millions of people were fooled by buying pyrite rather than gold.

Rocks 46. Explain the three characteristics that are used to classify

rocks.

The three characteristics that are used to classify rocks are:

- Composition: minerals that make up the rock.

- Texture: size and arrangement of the minerals in the rock.

- Origin: the way that the rock was formed.

47. Pumice is a rock that floats in water. Why do you think this is? Is it a natural or an artificial rock? Justify your answer.

Because it has many small holes in the surface. These were formed by gases that were in the rock before solidified.

48. Copy the following terms in two columns in your notebook and then match them:

Limestone Detritial Sedimentary

Granite Non-detritial Sedimentary

Clay Plutonic

Marble Volcanic

Basalt Foliated metamorphic

Chalk Non-foliated metamorphic

49. Are there any rocks which are not composed of minerals? What type of rocks are they?

Yes, coal and petroleum. These rocks are classified by looking at the origin of the sediments that compose them and are called sedimentary rocks.

50. When 1 kg of granite was analysed in the laboratory using different chemical processes they obtained 250 g of a white mineral, 300 g of another mineral, almost black, and the rest was a grey mineral.

CONSOLIDATION


3 The Geosphere

122

a) What is the name of each mineral that composes granite?

Feldspar, quartz and mica.

b) Which mineral corresponds to the grams of minerals above?

Feldspar: 250 g of a total of 1 000 g = 25 %

Quartz: 300 g of a total of 1 000 g = 30 %

Mica: 450 g of a total of 1 000 g = 45 %

51. On an excursion, Ana found a rock that contained a plant fossil that lived on Earth millions of years ago. What type of rock do you think it was? Explain your answer.

It is a sedimentary rock, it was probably formed on the Earth’s surface including a plant fossil between the sediments that originated it.

52. Which rock forms quartzite after metamorphism? What size are the grains of the original rock?

The sandstone, with a size above 2 mm.

The use of rocks 53. Explain which rocks provide the following building

materials.

a) Glass: sandstone

b) Concrete: mixed cement, water, sand and gravel (little fragments of sedimentary rocks).

c) Cement: limestone and clay

d) Lime: limestone

e) Brick: clay

f) Tiles: clay; although there are areas where tiles are made up by slates and similar materials.

54. Why are coal and petroleum referred to as fossil fuels?

They are combustible because they produce energy for the human beings. And they are fossils because they originate from the remains of living things.

55. What is sandpaper? Explain why it is not made of fragments of gypsum or talc.

It is an utensil used in building and DIY made up of a paper or cardboard in which there are fragments of hard sand stuck on it. It is used to smooth surfaces and it cannot be made up of gypsum or talc, because these have a low hardness.

56. Copy and complete the table in your notebook for the following rocks: petroleum, chalk, limestone, clay and coal.

ROCK USE OBJECTS CREATED WITH IT

PETROLEUM Combustible and raw material

Petrol or diesel and plastics such as bottles

LIMESTONE Building Cement

CHALK Building Roofs, walls, coating, etc.

CLAY Building Bricks

COAL Combustible Energy source

57. Research how concrete and bricks are made. Make a diagram.

For example:

Heating and milling of limestone and clay.

Mixed with sand, gravel and water.

Concrete

Milling and pulverization

of clay.

Mixed with water and

model.

Oven at high temperature:

cooking process.Bricks


58. Complete the sentences in your notebook.

a) The rocks extracted from quarries are cut into blocks.

b) Adits are horizontal tunnels in underground mines.

c) Gravel is a sediment that is usually extracted in or near large riverbeds.

59. Explain the meaning of the terms deposit and mine.

A deposit is the place where minerals are found in sufficient quantity to make extraction economically beneficial while a mine is the place that is more profitable to explore by human beings.

60. Find out what a waste dump is and what environmental problems it presents.

A waste dump is a place on the Earth’s surface where human beings throw rests of building materials such as bricks, cement, concrete, etc. Those places cause lots of environmental problems. Living things that used to live in those places will be moved or destroyed by those rests.

61. Discuss this statement: ‘New generation mobile telephones are made of stone.’

The statement means that a lot of materials that are used to make new generation mobile phones are extracted from the rocks.

READ AND UNDERSTAND SCIENCE

a) What is the text about?

It is about some giant crystals that were found in the cave of Naica, Mexico.

b) Can you explain the title?

The title refers to the velocity to form those crystals.

c) Why have the crystals stopped growing?

Due to mining activities to extract minerals.

d) Do you think the growth of these formation can be observed by any person?

No, because these formations grow at the equivalent of one hair every 100 years.

e) Find out about selenite. Explain why water is essential for its formation.

Selenite is a variety of gypsum made up of hydrated calcium sulphate, and it needs water during its process to hydrate.

STUDY SKILLS Open answer

CONSOLIDATION


123

3The Geosphere

Web page: THE EARTH’S CRUST AND ITS MATERIALS

Above the Earth’s crust, there are a group of inert materials such as minerals and rocks. This web page will help students to review the main contents of this unit and to do the activities.

CONCEPTUAL MAP

To introduce the contents of the unit, you could show to the student an incomplete conceptual map and ask them to complete the gaps in their notebook or orally with the whole group. This will help students to globally visualise the links between the different contents of the unit.

PRESENTATION

Use the slideshow presentation to show the different sections in the unit and to evaluate student’s learning. This tool can also be used as revision at the end. The slides can stimulate student participation, as they can be asked about certain topics before they study them.

REVISION ACTIVITIES

Various revision activities.

EXTENSION ACTIVITIES

Various revision activities.

Curricular adaptation: ASSESSMENT

Adapted for mixed abilities.

ASSESSMENT TEST

Assess the learning outcomes that are seen in the unit.

CONSOLIDATION


3 The Geosphere

124

WORK AND EXPERIMENTATION TECHNIQUES

The texture of rocks This science practical complements the contents worked in section 3. In that section the learning standard that is worked on is 7.1. Identify rocks using information that could differentiate them.

In addition, it will help students to become familiar with materials and instruments used in a laboratory such as the binocular loupe.

By doing this laboratory practical students will achieve the following key competences:

❚ Mathematical competence and basic competences in science and technology (MCST).

❚ Learning to learn (LL).

❚ Sense of initiative and entrepreneurship (SIE).

Answer key

1. Which of the observed rocks is homogeneous? How did you know?

Both sandstone and gneiss are homogeneous rocks. It is checked by observing them with a binocular loupe.

2. What are the main differences between conglomerates and sandstone?

Mainly the size of the grain, bigger in conglomerates.

3. What type of igneous rocks are granite and basalt? Can you observe any differences in their textures?

Granite is a plutonic rock while basalt is volcanic. The difference is visible on the texture and we can see the crystals on a naked eye in the granite.

4. Based on the results of this practical, define in your own words the different types of rocks (igneous, sedimentary and metamorphic).

Student’s own answer

5. Which of the rocks observed in this practical were formed in the exterior of the Earth’s crust? And in the interior?

Conglomerate, sandstone, basalt and gneiss were formed in the exterior of the Earth’s crust while granite was formed in the interior as being a plutonic rock.


3

The environmental impact of mineral extraction

FINAL TASK

The texture of rocks

WORK AND EXPERIMENTATION TECHNIQUES3

64

1. Which of the observed rocks is homogeneous? How did you know?

2. What are the main differences between conglomerates and sandstone?

3. What type of igneous rocks are granite and basalt? Can you observe any differences in their textures?

4. Based on the results of this practical, define in your own words the different types of rocks (igneous, sedimentary and metamorphic).

5. Which of the rocks observed in this practical were formed in the exterior of the Earth’ s crust? And in the interior?

1. Put each rock, one by one, on the slide of the binocular loupe. Look through the eyepieces and move the macrometric screw until the rock is sharply focused.

2. Observe each rock, and draw what you see for each rock.

3. Place a ruler next to the rock and, with the help of the loupe, measure the crystals or fragments that compose the rock.

4. Do another drawing of each rock observed.

Procedure

Some characteristics of rocks cannot be seen just by looking at them. In this practical, you will learn to use a binocular loupe to compare different rocks and distinguish them according to texture.

Materials

❚ Binocular loupe

❚ Five different rocks, for example, conglomerate, sandstone, basalt, granite and gneiss

❚ Ruler

Texture of conglomerate Texture of gneiss Texture of sandstone

To analyse the results and compare the rocks, use the following table next to your drawings:

Analysis of results

Name of rockMinerals it is composed of

Size of the components

Type of rock

... ... ... ...

Follow these steps for your research:

Research

❚ Find at least four different ways in which mines impact the environment and people. Suggest some possible solutions to the problems.

❚ Do not trust only one source of information. Check that the answers to your questions are repeated in different sources.

❚ Make a bibliography of all sources consulted.

Organise the information

❚ Make a table with the main impacts of coltan mining.

❚ Write the answers to the questions in the Research section.

Obtain conclusions and confirm research

❚ As a result of your work, resolve the initial questions of the Final task.

❚ Verify your answers.

❚ Check that you have answered all the questions.

Procedure

The objective of this task is to research the environmental and social impact of extracting coltan. You will present your information in a slideshow presentation

and suggest some measures to contribute to solving the problems.

a) What are the negative effects of mineral extraction on the environment?

b) What is coltan and what it is used for?

c) Where are the main coltan mines located? Are there any in Spain?

d) How does the behaviour of the consumer affect the exploitation of children in coltan mines? What can we do to help solve this problem?

1. Research

a) Prepare a slideshow presentation.

b) Make a list of three ways in which we can contribute to the sustainable management of mineral resources.

2. Tasks

❚ Answer these questions to evaluate your work.

1. Have you resolved all the questions in the Research section?

2. Have you used reliable sources to find information?

3. Have you checked that the answers were repeated in various sources?

4. What rating, from 1 to 5, would you give your presentation?

SELF-ASSESSMENT

+www

+www


125

3The GeosphereFINAL TASK

The environmental impact of mineral extraction The final task of this unit aims to raise awareness of the importance of the sustainable management of mineral resources. Nowadays, we live in a world of consumers, and we rarely ask ourselves where things we use come from, or the human costs and environmental needs. When new objects come out in the market, we do not appreciate the ones we have and often refuse to use them even if they still work properly. We do not even think about what to do with the objects we do not want anymore and how they can pollute the environment if we do not throw them away properly.

At the beginning of the unit, the final task and its objectives, in this case, were introduced with a slideshow presentation.

On page 47 we introduce the final task with some questions to motivate the curiosity of students.

On page 65 we explain how to do the research and how to prepare the slides.

❚ In the section Research there are four questions to guide students during the research.

❚ In the section Tasks there is a reminder about what they need to do.

❚ The Procedure section indicates the steps students must follow during the research, how they organise the information before making the slides, and the importance of reviewing all the information to make sure they are doing things correctly.

❚ The Self-assessment at the end of the page will make them think about their work and the development of the final task.

Unfortunately, there is no time to present all the slideshows. Choose one, or reduce the timing presentation and give the chance to another group.

The learning outcome that will be reinforced by doing this task, in the section 2, is the 10.1. Recognise the importance of minerals and rocks for humans and of managing these resources in a sustainable way.

The learning outcomes from sections 1 and 7 will be also developed.

An example of how to assess the final task is shown here:

0 = not handed in

1 = very basic

2 = well done

3 = excellent

0 1 2 3SLIDESHOW PRESENTATION

The presentation is adjusted according to the instructions.

Slides are eye-catching and the proportion of the texts and images is balanced.

Slides include information and images that complement the explanation.

The language, in the oral presentation, was expressed in appropriate and understandable terms.

Images sources consulted were mentioned.

Able to answer the questions proposed by the teacher and classmates.


3 The Geosphere

126

3 LEARNING OUTCOMES RUBRIC

Eval

uabl

e le

arni

ng

outc

omes

Ass

essm

ent t

ools

Exce

llent

3

Satis

fact

ory

2In

pro

cess

1N

ot a

chie

ved

0Sc

ore

1.1

Desc

ribe

the

form

atio

n pr

oces

s of

the

Earth

1, 4

2Ex

plai

ns th

e pr

oces

s in

a cle

ar

man

ner,

iden

tifyin

g al

l the

mai

n el

emen

ts.

Expl

ains

the

proc

ess i

n a

valid

bu

t inc

ompl

ete

way

, ide

ntify

ing

quite

a fe

w o

f the

mai

n el

emen

ts.

Expl

ains

the

proc

ess w

ith

mist

akes

, ide

ntify

ing

few

of t

he

mai

n el

emen

ts.

Answ

ers i

n an

inco

rrect

way

or

does

not

ans

wer

.

2.1

Rela

te th

e la

yers

of t

he

geos

pher

e an

d its

form

atio

n pr

oces

s.

3, 4

4Ex

plai

ns th

e pr

oces

s in

a cle

ar

man

ner,

iden

tifyin

g al

l the

mai

n el

emen

ts.

Expl

ains

the

proc

ess i

n a

valid

bu

t inc

ompl

ete

way

, ide

ntify

ing

quite

a fe

w o

f the

mai

n el

emen

ts.

Expl

ains

the

proc

ess w

ith

mist

akes

, ide

ntify

ing

few

of t

he

mai

n el

emen

ts.

Answ

ers i

n an

inco

rrect

way

or

does

not

ans

wer

.

3.1

Desc

ribe

the

mai

n ch

arac

teris

tics o

f the

mos

t fre

quen

t mat

eria

ls in

the

exte

rnal

are

as o

f the

pla

net

and

expl

ain

thei

r dist

ribut

ion

acco

rdin

g to

the

dens

ity.

2, 4

0, 4

1, 4

2, 4

3Ex

plai

n th

e co

ncep

ts in

an

appr

opria

te w

ay, i

dent

ifyin

g al

l the

mai

n el

emen

ts a

nd it

s re

latio

ns.

Expl

ains

the

conc

epts

in a

val

id

but i

ncom

plet

e w

ay, i

dent

ifyin

g qu

ite a

few

of t

he m

ain

elem

ents

and

its r

elat

ions

.

Expl

ains

the

conc

epts

with

m

istak

es, i

dent

ifyin

g fe

w o

f the

m

ain

elem

ents

and

its r

elat

ions

.

Answ

ers i

n an

inco

rrect

way

or

does

not

ans

wer

.

3.2

Desc

ribe

the

mai

n ch

arac

teris

tics o

f the

cru

st, t

he

man

tle a

nd th

e co

re a

nd th

e m

ater

ials

that

hav

e fo

rm th

em.

40, 4

1Ex

plai

n th

e co

ncep

ts in

an

appr

opria

te w

ay, i

dent

ifyin

g al

l the

mai

n el

emen

ts a

nd it

s re

latio

ns.

Expl

ains

the

conc

epts

in a

val

id

but i

ncom

plet

e w

ay, i

dent

ifyin

g qu

ite a

few

of t

he m

ain

elem

ents

and

its r

elat

ions

.

Expl

ains

the

conc

epts

with

m

istak

es, i

dent

ifyin

g fe

w o

f the

m

ain

elem

ents

and

its r

elat

ions

.

Answ

ers i

n an

inco

rrect

way

or

does

not

ans

wer

.

4.1

Unde

rsta

nd th

e co

ncep

t of

min

eral

s.4,

5, 9

Expl

ain

the

conc

epts

in a

n ap

prop

riate

way

, pro

vidin

g qu

ite a

few

val

id e

xam

ples

.

Expl

ains

the

conc

ept i

n an

in

com

plet

e w

ay, p

rovid

ing

quite

a fe

w v

alid

exa

mpl

es.

Expl

ains

the

conc

epts

with

m

istak

es, p

rovid

ing

limite

d or

no

n-ex

isten

t exa

mpl

es.

Answ

ers i

n an

inco

rrect

way

or

does

not

ans

wer

.

4.2

Appl

y th

e co

ncep

t of

min

eral

to re

cogn

ise if

a

subs

tanc

e is

or n

ot a

min

eral.

6, 7

, 8, 1

0, 4

7So

lves a

ll th

e ac

tiviti

es

corre

ctly.

Solve

s mos

t of t

he a

ctivi

ties

corre

ctly,

with

mist

akes

in so

me

of th

em.

Solve

s the

act

ivitie

s but

mak

es

mist

akes

in q

uite

a fe

w o

f th

em.

Answ

ers i

n an

inco

rrect

way

or

does

not

ans

wer

.

5.1

Iden

tify

min

eral

s usin

g in

form

atio

n th

at c

ould

di

ffere

ntia

te th

em.

11,1

2, 1

3, 1

4, 4

5, 4

6, 4

9, 5

0,

51, 5

2So

lves a

ll th

e ac

tiviti

es

corre

ctly.

Solve

s mos

t of t

he a

ctivi

ties

corre

ctly,

with

mist

akes

in so

me

of th

em.

Solve

s the

act

ivitie

s but

mak

es

mist

akes

in q

uite

a fe

w o

f th

em.

Answ

ers i

n an

inco

rrect

way

or

does

not

ans

wer

.

6.1

Desc

ribe

som

e of

the

mor

e fre

quen

t use

s of m

iner

als i

n ou

r da

ily li

fe.

15, 1

6, 4

8Ex

plai

n th

e co

ncep

ts in

an

appr

opria

te w

ay, p

rovid

ing

quite

a fe

w v

alid

exa

mpl

es.

Expl

ains

the

conc

epts

in a

val

id

but i

ncom

plet

e w

ay, p

rovid

ing

a fe

w v

alid

exa

mpl

es.

Expl

ains

the

conc

epts

with

m

istak

es, p

rovid

ing

limite

d or

no

n-ex

isten

t exa

mpl

es.

Answ

ers i

n an

inco

rrect

way

or

does

not

ans

wer

.

7.1

Unde

rsta

nd th

e co

ncep

t of

rock

.17

, 18,

31,

54

Expl

ains

the

conc

ept i

n a

clear

m

anne

r, pr

ovid

ing

quite

a fe

w

valid

exa

mpl

es.

Expl

ains

the

conc

ept i

n an

in

com

plet

e w

ay, p

rovid

ing

a fe

w v

alid

exa

mpl

es.

Expl

ains

the

conc

ept w

ith

mist

akes

, pro

vidin

g lim

ited

or

non-

exist

ent e

xam

ples

.

Answ

ers i

n an

inco

rrect

way

or

does

not

ans

wer

.

7.2

Reco

gnise

the

thre

e ty

pes

of ro

cks a

ccor

ding

to th

eir

orig

in a

nd id

entif

y th

e m

ain

char

acte

ristic

s of e

ach

one.

22, 2

3, 2

7, 2

8, 3

2, 3

3, 5

5,56

, 58

, Wor

k an

d la

bora

tory

pr

actic

al t

echn

ique

s

Solve

s all

the

activ

ities

co

rrect

ly.So

lves m

ost o

f the

act

ivitie

s co

rrect

ly, w

ith m

istak

es in

som

e of

them

.

Solve

s the

act

ivitie

s but

mak

es

mist

akes

in q

uite

a fe

w o

f th

em.

Answ

ers i

n an

inco

rrect

way

or

does

not

ans

wer

.

8.1

iden

tify

rock

s usin

g in

form

atio

n th

at c

ould

di

ffere

ntia

te th

em.

19, 2

0, 2

1, 2

4, 2

5, 2

6, 2

9, 3

0,

53, 5

7, 5

9So

lves a

ll th

e ac

tiviti

es

corre

ctly.

Solve

s mos

t of t

he a

ctivi

ties

corre

ctly,

with

mist

akes

in so

me

of th

em.

Solve

s the

act

ivitie

s but

mak

es

mist

akes

in q

uite

a fe

w o

f th

em.

Answ

ers i

n an

inco

rrect

way

or

does

not

ans

wer

.


127

3The Geosphere 3LEARNING OUTCOMES RUBRIC

Eval

uabl

e le

arni

ng

outc

omes

Ass

essm

ent t

ools

Exce

llent

3

Satis

fact

ory

2In

pro

cess

1N

ot a

chie

ved

0Sc

ore

9.1

Desc

ribe

som

e of

the

mos

t fre

quen

t use

of r

ocks

in o

ur

daily

life

.

34, 3

5, 3

6, 6

0, 6

1, 6

2, 6

3, 6

4Ex

plai

n th

e co

ncep

ts in

an

appr

opria

te w

ay, p

rovid

ing

quite

a fe

w v

alid

exa

mpl

es.

Expl

ains

the

conc

epts

in a

val

id

but i

ncom

plet

e w

ay, p

rovid

ing

a fe

w v

alid

exa

mpl

es.

Expl

ains

the

conc

epts

with

m

istak

es, p

rovid

ing

limite

d or

no

n-ex

isten

t exa

mpl

es.

Answ

ers i

n an

inco

rrect

way

or

does

not

ans

wer

.

10.1

Rec

ogni

se th

e im

porta

nce

of m

iner

als a

nd o

f man

agin

g th

ese

reso

urce

s in

a su

stai

nabl

e w

ay.

37, 3

8, 3

9, 6

5, 6

6, 6

7, 6

8,

Rese

arch

task

Expl

ain

the

conc

epts

in a

n ap

prop

riate

way

, pro

vidin

g qu

ite a

few

val

id e

xam

ples

.

Expl

ains

the

conc

epts

in a

val

id

but i

ncom

plet

e w

ay, p

rovid

ing

a fe

w v

alid

exa

mpl

es.

Expl

ains

the

conc

epts

with

m

istak

es, p

rovid

ing

limite

d or

no

n-ex

isten

t exa

mpl

es.

Answ

ers i

n an

inco

rrect

way

or

does

not

ans

wer

.


3 The Geosphere

128

OXFORD INVESTIGATION

TYPES OF RESOURCES AND METHODOLOGY USED TO MEET OBJECTIVES

● Interactive activities. Elaboration and verification of a hypothesis.

❍ Search for information on the Internet.

Watch videos.

❏ Analyse images.

■ Analyse texts (news articles, scientific articles, etc).

SECTIONS OBJETIVES AND CONTENTS METHODOLOGY

Minerals Identify that aligned atomic structures is a property in minerals (crystalline structure). ●

Recognise the two basic characteristics that define a mineral: chemical and structural composition. ●

Identify mineraloides as solid bodies without a crystalline structure. ●

Recognise the influence that a crystalline structure has on the properties of minerals.(Diamond/Graphite). ●

Concepts: mineral, mineraloide, crystalline structure

Rocks Find out the composition of rocks. Define the concept of rock. ●

Recognise the two basic characteristics that define a rock: mineralogical composition and texture. ●

Recognise the influence that texture has on the characteristics of rocks (marble, limestone). ●

Concepts: rocks, mineralogical composition, texture

Rocks Find out the main types of rocks. ❍

Find out the different processes that form rocks. ❍ Recognise the characteristics of rocks for each type (magmatic, metamorphic, sedimentary). ❍ ❏

Concepts: classification of rocks, magmatic rocks, metamorphic rocks, sedimentary rocks


Find out and identify the main types of mineral extractions ❍

Concepts: mineral extractions, superficial extractions, subterranean extractions, gravel pits, quarry

Final task Recognise minerals, rocks and types of deposits ❍ ❏

Analyse the social and environmental impact that could cause the mineral extraction. ■

Objectives, contents and methodology


129

3The GeosphereEXAM A

1. Write the difference between the following concepts:

a) Ore and gangue:

Ore refers to the minerals which are profitable to extract from a deposit while gangue refers to the ones that are not profitable to extract.

b) Colour of a mineral and streak of a mineral:

The colour is the appearance of the mineral while the streak is the color of the powder produced when a mineral is scratched.

c) Tenacity and cleavage:

Tenacity describes how easily a mineral breaks and cleavage describes the way a mineral breaks.

2. Make a complete classification of rocks according to their origin.

3. Why do the seismic methods help us to study the Earth’s interior?

Because the speed of the seismic waves vary as they pass from one layer to another. The study of the data obtained helped scientists to deduce the composition of the Earth’s interior and thanks to it we know that the Earth is divided into three layers: the crust, mantle and core.

4. The following diagram shows the layers of the geosphere. Write the name of each one of them and their discontinuities.

5. Explain what happens in the process of diagenesis or lithification.

It is the process in which sediments transform into sedimentary rocks.

Sediments deposited in sedimentary basins firstly suffer a process of compaction, when they lose volume due to the weight of them on top so they become compacted. After that, cementation takes place after the water is lost and the salts form crystals. The crystals act like cement and stick the sediments together to form sedimentary rocks.

6. Correct the following statements.

a) The conglomerate in a non-detrital sedimentary rock with a superior grain size up to 2 mm.

The conglomerate is a detrital sedimentary rock.

b) Sandstone is a detrital sedimentary rock that produces effervescence in contact with acids.

Sandstone does not produce effervescence.

c) All of sedimentary rocks are formed by minerals.

Coal and petroleum are formed by organic remains that have not decomposed.

d) Clay is made up of grains of a size inferior to 2 mm but easily visible.

The grains of clay only can be observed with a magnifying glass or a microscope.

7. Indicate the name of the processes mentioned:

a) Transforms a magma into igneous rock.

Cooling and solidification.

b) Transforms a sedimentary rock into metamorphic.

Metamorphism.

c) Transforms and igneous rock into sediments.

Weathering, transportation and sedimentation.

d) Transforms a metamorphic rock into magma.

Fusion.

8. What rocks are used as combustible fossils?

Coal and petroleum.

9. Give an example for each case:

a) Soft: calcite, fluorite or apatite

b) Very soft: talc or gypsum

c) Hard: orthoclase or quartz

d) Very hard: topaz, corundum or diamond

10. Look at the images below and explain the types of the superficial extractions.

The image on the left is a quarry. In quarries, large rocks are extracted and cut into blocks or slabs.

The image on the right is an opencast mine. The minerals are not deep underground so to extract them, they make funnel-shaped holes (pits). The edge are stepped to transport the minerals to the surface.


3 The Geosphere

130

EXAM B

1. Indicate the similarities and differences between opencast mines and underground mines.

They are both mines to extract minerals. In opencast mines, minerals are extracted from the surface or hot very deep under the surface while in underground mines they make funnel-shaped holes called pits to extract the minerals.

2. Match the following minerals to their hardness:

Very hard Diamond

Gypsum

Hard Topaz

Apatite

Soft Talc

Quartz

Very soft Orthoclase

Calcite

3. Observe the following drawing and explain how the Earth was formed.

4 600 billions of years ago the Sun was formed from chemical reactions in a giant cloud of dust and gas called nebula. In the cloud of matter that surrounded the Sun, smaller dust particles collided and grew in size. This process which formed the planets is called accretion of planetesimals.

For 1 000 million years the Earth was incredible hot. Due to the immense heat stored in the Earth’s interior, there was a lot of volcanic activity during the period. As the Earth’s temperature decreased, gravity pushed heavier elements, such as iron, towards the Earth’s interior. Lighter elements, such as oxygen, moved towards the Earth’s surface. This process is called density differentiation.

4. Draw an explanatory diagram of the parallel layers of minerals in foliated metamorphic rocks. Why does this reorientation happen?

It happens because of the pressure on the rocks.

5. Correct the following statements.

a) Volcanic rocks cool slower than plutonic rocks. Plutonic rocks cool slower than volcanic rocks. b) Basalt is the most abundant volcanic rock in the

continental crust. Granite is the most abundant volcanic rock in the continental crust.

c) Plutonic igneous rocks are also called extrusive rocks.

Plutonic igneous rocks are also called intrusive rocks.

d) Granite is the most abundant volcanic rock in the continental crust.

Granite is a plutonic rock.

6. Answer the following questions:

a) What is the effervescence of a mineral?

It is the capacity to produce bubbles in contact with acids.

b) What does it mean if a mineral has a crystalline structure?

It means that the particles are arranged to form a geometric structure that is repeated constantly.

7. Indicate the ore that correspond to each mineral.

a) Bauxite: aluminium

b) Chalcopyrite: tin

c) Galena: lead

d) Hematite: iron

8. What are decorative rocks and what are they used for? Give some examples.

Decorative rocks are the ones that after cut and polished are so beautiful that they could be used to make sculptures, building floors or any other element of decoration. Marble, granite and basalt are great examples of decorative rocks.

9. Explain the rock cycle.

The rock cycle is a series of processes that a rock goes through to transform into another type of rock. These processes occur very slowly, so the rock cycle takes place over millions of years. All rocks, exposed to the action of wind and water, can undergo the processes of erosion, transportation and sedimentation. Sediments deposited in sedimentary basins undergo the process of diagenesis or lithification and are transformed into sedimentary rocks.

The rocks in the Earth’s crust are subjected to high pressures and/or temperatures from metamorphic rocks. If the mineral melts, magma will form. Magma can rise and cool under the crust, creating plutonic igneous rocks. Magma can also come out of the crust to the exterior and solidify, creating volcanic igneous rocks.

10. Look at the following diagram and explain the formation of sedimentary rocks.

The process in which sediments transform into sedimentary rocks is called diagenesis or lithification.

Sediments deposited in sedimentary basins (1) often follow two essential processes for the formation of sedimentary rocks:

Compaction (2) is when sediments lose volume. Due to the weight of the sediments on top, water is lost and the sediments become compacted.

Cementation (3) takes place after the water is lost and the salts form crystals. The crystals act like cement and stick the sediments together to form sedimentary rocks.


geology 1eso ud03 lp - blinklearning · geology_1eso_ud03_lp.indd 100 25/03/15 10:02. 101 the...

Documents