rocks and minerals

Chapters 10 & 11Chapters 10 & 11

Rocks and Minerals Rocks and Minerals • Science, 8• Science, 8thth Grade Grade

Rocks and Minerals


Rocks

• Earth’s crust is made of rock.

• Rocks are mixtures of minerals and sometimes other materials.

background image source: http://veimages.gsfc.nasa.gov/7100/world.topo.bathy.200401.3x5400x2700.jpg

http://college.hmco.com/geology/resources/geologylink/glossary/r.html

http://college.hmco.com/geology/resources/geologylink/glossary/m.html

http://veimages.gsfc.nasa.gov/7100/world.topo.bathy.200401.3x5400x2700.jpg


Studying Rocks

• When studying a rock sample, geologists observe the rock’s:– Color

• click here for a rock color chart

– Texture– Chemical Composition

http://www.google.com/search?hl=en&q=define%3A+geologist

http://www-swiss.ai.mit.edu/~jaffer/Color/RC.htm


Color Chart Quiz

image source:http://geology.about.com/library/bl/images/blgneiss.htm

Click the color on the color chart that best identifies the color of the rock above.

http://geology.about.com/library/bl/images/blgneiss.htm

http://geology.about.com/library/bl/images/blgneiss.htm


That is not correct…

• Please click on the “Back” button and try again.

Back


Excellent!• You have correctly identified the rock on the color chart.

Click on the “Next” button to continue.

Next


Texture

• Most rocks are made up of grains, particles or minerals, or other rocks.

• Texture is the look that results from:– Size– Shape– Pattern of rock’s grains


Grains• Coarse-grained: large/easy to see• Fine-grained: small, even microscopic

– Click here for rock identification tables that include information on grain size.

Obsidian – A Fine-grained Rockimage source: http://geology.about.com/library/bl/images/blobsidian.htm

Sandstone – A Coarse-grained Rockimage source: http://geology.about.com/library/bl/images/blsandstone.htm

http://geology.about.com/library/bl/blrockident_tables.htm

http://geology.about.com/library/bl/images/blobsidian.htm

http://geology.about.com/library/bl/images/blobsidian.htm

http://geology.about.com/library/bl/images/blsandstone.htm



Grain Pattern

• Grains in rock often form a pattern.– Flat layers (strata)– Wavy, swirling patterns– Rows of beads– Random or no pattern

Example

Example

Example

Example


Flat Layers (strata)

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Wavy, Swirling Patterns

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Rows of Beads

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Random or No Pattern

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Quick Forming Rocks

• Some rocks have no grain because they cooled too quickly when they formed.

http://www.fi.edu/fellows/fellow1/oct98/create/index.html


Rock Groups

• There are three groups of rocks:– Igneous– Metamorphic– Sedimentary

• Click on the links above to find the definition of each group of rock. Once you have reviewed these definitions online, click on the arrow to continue.

http://college.hmco.com/geology/resources/geologylink/glossary/i.html

http://college.hmco.com/geology/resources/geologylink/glossary/m.html

http://college.hmco.com/geology/resources/geologylink/glossary/s.html


Igneous Rocks

• Formed from the cooling of molten, or melted, rock

Pumice Granite Basalt

http://volcanoes.usgs.gov/Products/Pglossary/pumice.html

http://www.fi.edu/fellows/fellow1/oct98/expert/granite.htm

http://volcanoes.usgs.gov/Products/Pglossary/basalt.html


Metamorphic Rocks• Formed when existing rock is changed by

heat, pressure, or chemical reactions

Gneiss Schist Phyllite

http://seis.natsci.csulb.edu/bperry/metarock/GNEISS.htm

http://seis.natsci.csulb.edu/bperry/metarock/SCHIST.htm

http://seis.natsci.csulb.edu/bperry/metarock/PHYLLITE.htm


Sedimentary Rocks• Formed when particles of other rocks,

plants, or animals are cemented together

Sandstone Breccia Siltstone


http://geology.about.com/library/bl/images/blbreccia.htm

http://geology.about.com/library/bl/images/blsiltstone.htm


The Rock Cycle

Click here for another illustration of the rock cycle.

http://www.oum.ox.ac.uk/thezone/rocks/cycle/index.htm#map


Online Rock Cycle Activities• The Rock Cycle

– Click on the image below to access online resources and activities.

http://www.oum.ox.ac.uk/thezone/rocks/cycle/help.htm


Minerals

• A mineral:– Occurs naturally– Is inorganic– Is Solid– Has a crystal structure– Has a definite chemical composition


Minerals

• There are three thousand (3000) minerals.

• One hundred (100) minerals are common.

• Twenty (20) minerals make up most of the rocks of Earth’s crust (rock-forming minerals).


Mineral Formation

• Minerals form through:– Crystallization of melted materials.– Crystallization of materials dissolved in

water.


Crystals

• Repeating patterns of a mineral’s particles that form a solid.– Click here for a

crystal experiment from National Geographic.

http://www.nationalgeographic.com/ngkids/trythis/tryfun1.html

http://www.mineralminers.com/images/andalusite/mins/anlm108c.jpg


Mineral Composition• All minerals contain certain elements in

definite amounts.• Most minerals are compounds (two or

more elements).• Silver and gold are considered minerals.


Mohs Hardness Scale• The Mohs Hardness Scale ranks ten

minerals from softest to hardest.

source: http://www.amfed.org/t_mohs.htm

http://www.amfed.org/t_mohs.htm





Ranking Minerals

• Minerals are ranked according to:• Click on the word below for more information.

– Color– Streak– Luster– Density– Cleavage– Fracture


Color

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Streak

• Streak is the color of a mineral’s powder.

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Luster

• Luster is how shiny a mineral is.

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Density

• Density is mass per unit volume (specific gravity).

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Cleavage

• Cleavage is the breaking of a mineral along a regular line.

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Fracture• Fracture is the irregular breaking of a mineral.

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Fluorescence

• Fluorescence refers to minerals that glow under ultraviolet light.


Magnetism

• Magnetism occurs naturally in some minerals, such as magnetite.


The End

• Click here for another online resource about rocks and minerals.

• Click the arrow below to return to the beginning of this presentation.

rocks and minerals

Documents

minerals science

mixtures of minerals

rockssome rocks

gradenexttexturemost

groups of rocks

rock sample

existing rock

group of rock