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Unit 3 Minerals and Rocks Study Guide

(Chapters 3, 4, 5, 7) (Revised 7/16)

UNIT 3 HOMEWORK worth 10 points

Team written tables about minerals (see end of this unit for a guide, pages 10 - 11)

For any Unit Web Hits, go to the “DMC HOME” website; in Search box –type “Geology”, select “Vernon

Kramer”, scroll down to GEOL 1303, select “Syllabus”, select “Web Hit Links”, click on icon of interest for web sites

OR: go to DMC Home website, select “Degrees, Certificates, Courses”, scroll down to Natural Sciences and select

“Geology”, select “Faculty Listings”, select “Walter Vernon Kramer”, find “Geol 1303”, select “Syllabus”, and there

you can find the” web hit links” click on icon of interest for web sites

[IF NONE OF THE WEB SITES COME UP, YOUR COMPUTER PROBABLY NEEDS TO BE REBOOTED (RESTARTED)

- Questions: Did you complete your portion of the team written tables about minerals?

Some General Chemistry Terms (Chapter 3)

Matter: anything that has mass and occupies space

- Matter is made up of elements which are composed of atoms

Element: chemical matter made up of one kind of atom

Atom: the smallest unit of an element that retains the characteristics of that element

An atom is composed of a nucleus of protons and neutrons, surrounded by a shell of orbiting electrons.

- Rocks and minerals are natural chemicals composed of combinations of various elements (possibly

silicon iron, magnesium, carbon, oxygen, etc.).

Atoms and Elements from Stars

- Most of the original known universe was composed mostly of two elements: hydrogen and helium

with a minor amount of lithium.

- All of the remaining elements were “created” within various types of star, sometimes explosively.

- Our sun is using nuclear fusion to create different elements from hydrogen and helium atoms at a rate

of 700 million tons of hydrogen per second!

- Thus it is within the stars (like our sun) where smaller atoms will use nuclear fusion to create most of

the dozen or so elements that we find within Earth’s rocks and minerals and atmosphere.

- Most of the remaining natural elements we find on Earth were created from supernovas (exploding

massive stars that began as a mass of hydrogen and helium).

We are literally made from star stuff - Carl Sagan

- (Page 61 is a Periodic Table of all known elements)

FYI: Our sun is a third generation star.

Atoms after Supernovas

- This formation process of creating more elements is repeated throughout the known universe. Thus

we should expect to find the same elements, compounds and minerals everywhere in our universe.

- FYI: A molecule is the smallest unit of a substance. Example is a “single unit” of H2O or 02

- FYI: Compound: chemical substance formed by the bonding of two or more different elements

(NaCl, H2O, etc.). (If you are interested, your book presents some details of how these atoms

combine to form minerals.)

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Most Abundant Elements in the Earth’s Crust

- The two (2) most abundant elements of the Earth’s crust (75%) include oxygen (47%), and silicon

(28%). These same elements are easily created from a star the size of our sun.

- The formation of space dust and molecules is the same for all galaxies. Thus the initial rocks and

minerals on most planets and other rocky bodies should be very similar to those on Earth.

Concept Test

Earth’s Composition

- It is rocks and minerals (which are actually chemical compounds) that make up both the Earth’s

crusts and the Earth’s mantle.

Mineral Definition

Mineral: a natural occurring inorganic solid with specific crystal structure, a specific chemical

composition and with specific physical properties. (Ch. 3)

All Minerals Must Possess Certain Characteristics

- A mineral is a natural occurring substance that is not man-made.

- A mineral is inorganic and cannot be composed of any decayed plant or animal matter. For example

coal (organic) is not considered by geologists to be a mineral because it is composed of decayed

organic matter.

- Why are coal and oil and gas classified as minerals by the US GOVT.? – For tax purposes. Minerals

are taxed at a higher rate than rocks.

- A mineral must be a solid. Snow and natural ice are minerals but water is not.

-A mineral has a specific range of chemical compositions. The composition may be as simple as gold

or complex as the mica biotite.

- A mineral has a specific crystal structure.

Crystal: the arrangement of atoms in a solid that form in a regular, repeating three dimensional pattern.

- Crystal structures defined different minerals even though, for some, their chemical compositions can

be identical.

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Diamonds and Graphite (The Following Is Always Referenced on Exams)

- Diamond and graphite are two different minerals both composed of the element carbon. Their major

physical differences are caused by different crystal structures.

- Graphite (an extremely soft mineral) has a totally different crystal structure than the world’s hardest

mineral (diamond).

- Nothing on Earth is harder than a diamond.

- A one carat diamond equals in weight to a single 2” X 2” Post-it note sheet

Diamonds are a girl’s best friend – Carol Channing

FYI: Gem-quality diamonds can be created from the cremated remains of a loved one or a pet - for a

large fee. Go to LifeGem.com for more information.

Nine (9) Physical Properties of Minerals (only have to remember *3, *4 or *5 for exam)

Minerals have many specific physical properties which can be used for their identification.

1. Crystal faces and shape

2. Density (light vs. heavy)

*3. Cleavage shape often taken when a minerals is broken; such as cubes of halite

*4. Hardness resistance to abrasion, often compared to other minerals

*5. Color: color is a problem because one mineral may have many colors 6. Streak; color when scratched or the color of the powdered mineral

7. Luster: reflected light; metallic vs. non-metallic vs. earthy as an example

8. Magnetism (only a few minerals are magnetic)

9. Taste (example is salt)

Identifying Minerals

- Identifying minerals is like identifying people. You don’t always have to use all of the characteristics

to identify that person.

Get your facts first, and then you can distort them as much as you please – Mark Twain

Common Texas Minerals

1. Halite (NaCl - sodium chloride) is a mineral that we all call “salt”. It is an evaporate mineral found

in some dry lake beds in West Texas and sometimes along Laguna Madre. Halite is also found in

large GOM salt domes where it is called rock salt. Halite is usually white to clear, forms cubic

crystals (because of its atomic structure) and tastes salty. Halite has a cubic cleavage (breaks into

cubes). It is used for preserving meats, french fries, Draino, leather products, de-icing roads, etc.

2. Mineral gypsum (calcium sulfate with water) is an evaporate mineral that is found in soils and sands

throughout the Corpus Christi area. Gypsum has a hardness of two (which means that gypsum can

be scratched with your fingernail) and has perfect cleavage (breaks into smooth sheets). It is used as

a soil conditioner (especially for black-sticky soil), Plaster of Paris, Alabaster carvings and most

importantly – sheetrock.

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Scratching gypsum

3. Mineral sulfur is an element (S) and it is also a yellow-colored mineral. Sulfur is commonly found

in the cap rock of salt domes and near steam vents that surround volcanoes. Trace amounts of sulfur

are essential for life but large quantities can be toxic. Sulfur is used for gunpowder, medicine, and

agriculture and during the refining of gasoline. Rotten-egg smell is produced by sulfur dioxide. In

ancient times, sulfur was called brimstone.

4. Mineral calcite (calcium carbonate - CaCO3) cleaves (breaks) itself into a rhombic pattern. This

mineral creates the rocks limestone and caliche. Massive quantities of calcite rocks are found

throughout Texas as large deposits of caliche (found in the Mathis area). (Pits are seen alongside the

highway.)

5. Mineral magnetite (Fe3O4) is a heavy, hard, black mineral that is a natural magnet. It is commonly

found in beach and river sand and deposits in Central Texas. Magnetite is the principle mineral of

iron ore.

Silicate Minerals Approximately 75% of the Earth’s mass is made up of silicon and oxygen.

- Silicate minerals (minerals with some silicon & oxygen) are the most common minerals on Earth.

Silicates form more than 1/3 of all known minerals

6. Silicate mineral quartz (silicon dioxide SiO2) is very hard. Quartz can scratch glass. But steel

cannot scratch quartz. Quartz in CC area includes beach and river sands, and chert (flint or gravel).

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- Quartz gemstones include amethyst, agate, and rose quartz. Melted quartz sand is used to make

glass. Sand and chert are among the most important components of concrete used with the building

industry.

7. The feldspar group of silicates includes orthoclase. Orthoclase has a rectangular cleavage.

Orthoclase is used in making ceramics. We will most often notice orthoclase as the “salmon-

colored” mineral in granite.

8. The mica group silicates include biotite (black) and muscovite (clear). All have planar cleavage and

break into very thin flexible sheets. Biotite is one of the black minerals that we find within granite.

9. Olive-green olivine is one of the most common mineral in the known universe. Clear olivine is

often cut into the gemstone peridot.

Where Do Minerals Form?

- Minerals can form in many environments including in space as galactic nebula and molecular clouds.

- On Earth, minerals can be formed by many methods:

1. From the cooling of magmas and lavas

2. From evaporation of mineralized waters or fluids

3. From reactions with natural acid waters

4. As a byproduct of living organisms: grass (quartz), sea plants and sea animals (quartz and

calcite), and animals (mineral apatite in bones and teeth)

Rocks

Rock: a naturally occurring aggregate of one or more minerals.

Diplomacy is the art of saying “Nice Doggie” until you can find a rock – Will Rogers

Creation of Rocks - Rock can be formed from many processes:

1. A rock may be a solid made from a combination of minerals.

2. A rock might be a very large body or deposit made of a single mineral (halite vs. salt).

3. A rock may be solidified organic matter formed by biochemical processes (coal, peat, etc.).

4. A rock composed of quartz or calcite can be created by biochemical processes (chert and

limestone).

- Mineral combinations make up most rocks.

Rock Systems

- Rocks are formed in three geological systems:

1) Igneous System rocks;

2) Sedimentary System rocks

3) Metamorphic System rocks.

- Each system contains a collection of different rock names and types.

- The rock types differ from each other by size, shape and arrangement of the mineral grains.

- Rocks can be modified by different geological environments (systems) – for example sedimentary

rock sandstone can be melted to become an igneous rock.

Those are my principles, and if you don’t like them… well, I have others – Groucho Marx

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Rock Cycle

- All three systems of rocks are interrelated with each other and are part of a “rock cycle” (BE ABLE

TO DEFINE from a model)

Rock cycle: a general model that describes how various geologic processes can create and modify

rocks.

- Plate tectonics and the hydrologic system are responsible for the recycling of rock material and are

the driving forces that can take hundreds of millions of years to completely change a rock.

The Rock Cycle

Concept Test

Igneous Rock System Definitions (Ch. 4 & 5)

IGNEOUS ROCK: a rock solidified from a molten state

MAGMA: molten rock within the Earth’s surface

LAVA: a molten rock (magma) that has reached the Earth’s surface

- If the rock is melted – it is a magma or lava. If the rock is no longer melted and is solid – it’s an

igneous rock.

EXTRUSIVE ROCKS: an igneous rock that formed on the Earth’s surface from the cooling of lava;

often referred to as volcanic rocks; generally has some gas bubbles

INTRUSIVE ROCKS: an igneous rock that formed from the cooling of magma, under the surface of

the Earth; generally has visible crystals

Some Locally Found Igneous Rocks

Scoria: A low density, dark-colored mafic extrusive igneous rock containing abundant gas vesicles

(exploded from a volcano)

- Scoria is usually black but acid gasses can cause the scoria to be red. Scoria is used for BBQ pits and

decorative rocks

Pumice: A low density, light-colored felsic extrusive igneous rock containing abundant gas vesicles

that was exploded from a volcano.

- Pumice is the only igneous rock that floats on water and is commonly found on Padre Island.

- Pumice is often sold for foot care and is used for abrasion.

Granite: a coarse-grained, light-colored, felsic intrusive igneous rock composed of Biotite, Orthoclase

(Feldspar) and Quartz

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- The nearest Texas granite mass is the Enchanted Rock, NW of San Antonio.

Sediments - There must first be a sediment before there can be a sedimentary rock.

Sediment: unconsolidated (loose) earth material, with sizes that range from gravel to mud; would

include any natural substance transported and deposited by wind, water, ice and gravity

Two General Classifications of “Sediments” (needed to make sedimentary rocks):

1. Clastic or Detrital sediments: solid particles derived from pre-existing rocks

2. Chemical sediments

A. Biochemical sediments: solid particles created by plants and animals

B. Evaporation sediments: solid particles derived from evaporation

Sediments Form Layers of Sediments that Eventually Become Sedimentary Rocks

- Sediments are deposited into layers which will compact to form rock layers.

Lithification: a process of compaction and/or cementation that changes sediments into a rock

The Different Classifications of Sediments Produce Different Types of Sedimentary Rocks

1. Clastic or Detrital Sedimentary Rocks: Rocks that are consolidated from clasts (pieces) of other

rocks

Sandstone: rock made of consolidated sand-size particles

Conglomerate: rock made from consolidated sand and gravel sized particles

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Cementation is accomplished by precipitation of minerals within sediments (coating with minerals of

calcite, silica or iron)

2. Chemical Sedimentary Rocks

A. Rocks that are consolidated from biochemical processes of vegetation

Coal: vegetation matter modified by biochemical processes and consolidated into a rock

- Coal is burned for electricity production (40%-50% of US electricity) and for making chemicals and

cosmetics

- FYI: Human bodies thrown into swamps and peat bogs can turn into coal – Google “peat bog man”

B. Rocks derived from skeletons of microscopic plants and animals

Limestone: a carbonate rock (calcite) consolidated from muds of plant and animal skeletons

- Large areas of Texas are underlain with limestone

- Limestone commonly contains fossil sea shells and sea animal fossils

- Limestone has removed huge quantities of carbon dioxide from the atmosphere.

C. Rocks derived from consolidated muds

- Another rock that is big in South Texas is shale which is basically consolidated, harden muddy

limestone, that can be rich with organic material and this includes the Eagle Ford shale

- The Eagle Ford shale has led to a major oil and gas boom in South Texas

- All of this is possible because of direction drilling and fracturing or fracking with sand and water to

open up the rock so that the oil/gas can escape into the pipes.

D. Rocks that are consolidated from evaporation and/or precipitation

Caliche: a “powdery” type of “evaporative” limestone found throughout South Texas, especially near

Mathis; used for road construction

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Concept Test

Nature does nothing uselessly - Aristotle

Metamorphic System Rocks

- Rocks formed from pre-existing rocks that have been subjected to great heat and pressure

- Metamorphic rocks often appear squashed and shiny

Metamorphism: A process where the original material (rocks) has been changed (recrystallized)

because of great heat and/or great pressure into a new appearance (same material)

- There are two classifications of metamorphic rocks (and both types are found in Central TX and West

TX)

1. Foliated (layered): example is Gneiss: (metamorphosed granite) a coarse grained

metamorphic rock with alternating light and darker colors (foliated)

2. Nonfoliated (not layered): example is Marble: metamorphosed limestone can be found at

Marble Falls, TX (NW of San Antonio).

- Remember that limestone and marble are composed of the mineral – calcite!

SEE PAGES 10 – 11 FOR INSTRUCTIONS FOR RESEARCH PAPER

Consider having the Stone Writing Center review your paper SEE GRADING RUBRIC FOR TEAMWORK PAGE 11

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Teamwork Research – (Two Parts) Rocks and Minerals Unit 3

Any advanced society must use rock and minerals and metals derived from minerals. And these substances

must be taken from the Earth (mined) in order to use them. Our society can only exist because of mining for

minerals somewhere on Earth. As our society becomes more advanced, we use a wider range of metals and

minerals for almost everything in our lives. Thus recycling of minerals and metals takes on a greater importance

to our society. But what minerals and metals are we using? Are we using “conflict minerals”?

Your Team assignment is to select one of four categories of a list of items to do your research. You are to

search numerous web sites and make a list of minerals and metals used (suggested form given below). You are

to make copies of your list for your teammates and each student is to discuss within the group their findings.

One thing you will discover is our increasing use of REE or Rare Earth Elements which is hard to find and

extract.

PART 1: Below are the 4 categories available (a different one for each team member):

A. An automobile (list should include more than 25 minerals/metals) (Google: minerals in automobiles -list

minimum 2 websites used). List must include least 25 Metals/elements used (column 1) with an

associated minerals (Column 2). Google: _____ minerals (i.e. lead, sulfur, iron, etc.) for a choice list of

minerals

B. A computer including all its chips (list should include more than 20 minerals/ metals) (Google: minerals

in computers -list minimum 2 websites used). List must include least 20 Metal/element used (column 1)

with an associated minerals (Column 2); Google: _____ minerals (i.e. lead, sulfur, iron, etc.) for a

choice list of minerals

C. Cell phones of various types (list should include more than 10 minerals/metals) (Google: minerals in

cell phones -list minimum 2 websites used). List must include least 25 Metal/element used (column 1)

with an associated minerals (Column 2). Google: _____ minerals (i.e. lead, sulfur, iron, etc.) for a

choice list of minerals. ALSO INCLUDE A PARAGRAPH IN YOUR OWN WORDS ABOUT THE

USE OF CONFLICT MINERALS TO MAKE A CELL PHONE

D. Include at least 4 types of light bulbs such as incandescent bulbs, CFL bulbs, neon lights, LED (list

should include more than 20 minerals, metals and gasses.) (Google: minerals light bulbs -list minimum

2 websites used) List must include least 20 Metal/element used (column 1) with an associated minerals

(Column 2). Google: _____ minerals (i.e. lead, sulfur, iron, etc.) for a choice list of minerals

PART 2: General rules:

1. To be typed: (include ONLY a list of actual websites that you used as references)

2. Column 1: with the metals, or elements or actual mineral used, etc. in alphabetical order;

3. Column 2 are the host minerals (from possibly a mineral website) that matches the metal or element.

4. If the website does not list a metal but a mineral instead, put its name also in the metal column

Column 1 Column 2

Example: Metal/Element Used Mineral Source (for a gas – use air for its mineral source)

1. Iron magnetite

2. Lead galena

3. Neon neon gas

Printed form to use can be a word document or a spreadsheet.

INDIVIDUALLY: WORTH EIGHT (8) POINTS IF TURN IN ON TIME NOT ACCEPTED LATE (and

2 points for team work)

ALL WORK (INCLUDING TEAM WORK) IS DUE CLASS AFTER EXAM 2

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TEAMWORK SKILLS Aspect 2: Be able to work effectively with others to support a shared purpose or goal.

I will assign a zero (0) to any work sample that does not meet Benchmark Expectations. Exceeds Target Expectations 2

points

Meets Target Expectations 1

point

Below Benchmark Expectations

0 points

Contributes to

Team Meetings

Advances the work of the group by

a. achieving Target Expectations AND b. articulating the merits of

alternative ideas or proposals.

Advances the work of the group by

a. offering new suggestions to

advance the work of the group

AND/OR

b. offering alternative solutions

or courses of action that build on

the ideas of others.

Shares ideas but does not advance the work

of the group

Individual

Contributions outside of Team Meetings

a. Achieves Target Expectations and at

least one of the following

b. Work accomplished is thorough

and comprehensive.

c. Proactively helps other team

members complete their assigned

tasks to a level of excellence.

a. Achieves Benchmark Expectations

AND

b. Work accomplished advances

the project.

Completes all assigned tasks by a deadline.

Fosters

Constructive

Team Climate

Supports a constructive team climate by

doing at least three of the following:

a. Treats team members respectfully

by being polite and constructive in

communication.

b. Uses positive vocal or written tone,

facial expressions, and/or body

language to convey a positive attitude

about the team and its work.

c. Motivates teammates by

expressing confidence about the

importance of the task and the

team’s ability to accomplish it.

d. Provides assistance and/or encouragement to team members.

Supports a constructive team climate

by doing two of the following:

a. Treats team members

respectfully by being polite and

constructive in communication.

b. Uses positive vocal or written

tone, facial expressions, and/or

body language to convey a positive

attitude about the team and its

work.

c. Motivates teammates by

expressing confidence about the

importance of the task and the

team’s ability to accomplish it.

d. Provides assistance and/or encouragement to team members.

Supports a constructive team climate by

doing one of the following:

a. Treats team members respectfully by being

polite and constructive in communication.

b. Uses positive vocal or written tone, facial

expressions, and/or body language to convey

a positive attitude about the team and its

work.

c. Motivates teammates by expressing

confidence

about the importance of the task and the

team’s ability to accomplish it.

d. Provides assistance and/or encouragement to team members.