Rocks, Minerals & the Rock Cycle

Section 1 Minerals and Mineral Resources

Objectives• Define the term mineral.

• Explain the difference between a metal and a nonmetal, and give two examples of each.

• Describe three processes by which ore minerals form.

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Mineral Resources

• We depend on the use of mineral resources in almost every aspect of our daily life.

• However, our dependence on minerals has not come without a price.

• The current challenge is to obtain the minerals that an ever-increasing world population demands at minimal cost to the environment.

Mineral Consumption per Person (U.S.)

What Is a Mineral?

• A mineral is a naturally occurring, usually inorganic solid that has a characteristic chemical composition, an orderly internal structure, and a characteristic set of physical properties.

• Minerals are made up of atoms of a single element, or of compounds. A compound consists of atoms of two or more elements chemically bonded together.

• The atoms that make up minerals are arranged in regular, repeating geometric patterns.

Section 1 Minerals and Mineral Resources

What Is a Mineral?• The arrangement of the atoms, along with the

strength of the chemical bonds between them, determine the physical properties of minerals,

• Some elements, called native elements, are considered minerals. These include the elements gold, silver, and copper.

• Most minerals, however, are compounds.

• The mineral quartz is made up of silica, which consists of one silicon atom and two oxygen atoms.

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Section 1 Minerals and Mineral Resources

Ore Minerals• An ore mineral is a mineral that contains one or

more elements of economic value.

• During the mining process, gangue minerals, minerals with no commercial value, are extracted along with ore minerals.

• Ore minerals, once separated from the gangue minerals, are refined using various methods to extract the valuable elements they contain.

• For mining to be profitable, the price of the final product must be greater than the costs of extraction and refining.

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Ore Minerals

Section 1 Minerals and Mineral ResourcesChapter 16

Section 1 Minerals and Mineral Resources

Metallic Minerals• Ore minerals are either metallic or nonmetallic.

• Metals have the following characteristics:• can conduct electricity• have shiny surfaces• are opaque

• Many valuable metallic minerals are native elements, such as gold, silver, and copper.

• Other important ore minerals are compounds of metallic minerals with nonmetallic elements.

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Section 1 Minerals and Mineral Resources

Nonmetallic Minerals• Nonmetals have the following characteristics:

• tend to be good insulators• may have shiny or dull surfaces• may allow light to pass through

• Nonmetallic minerals can also be native elements or compounds.

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Section 1 Minerals and Mineral Resources

How Do Ore Minerals Form?• Economically important ore deposits form in a

variety of ways, both on and beneath Earth’s surface.

• The types of mineral that form depend on the environment in which they form.

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Mineral Environments

Section 1 Minerals and Mineral ResourcesChapter 16

Section 1 Minerals and Mineral Resources

Hydrothermal Solutions• Hot, subsurface waters that contain dissolved

minerals are called hydrothermal solutions.

• Hydrothermal solutions dissolve minerals as they flow through cracks in rocks.

• New minerals crystallize out of these solutions and then fill fractures to form ore deposits called veins.

• Many economically valuable metallic ores form in this way.

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Section 1 Minerals and Mineral Resources

Evaporites• When water in the seas or lakes evaporate,

they leave behind deposits of salts called evaporites.

• Evaporites form in arid regions where rates of evaporation are high.

• Halite (rock salt) and gypsum are important evaporite minerals.

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Section 1 Minerals and Mineral Resources

Mineral Resources and Their Uses• Certain metals are of major economic and

industrial importance.

• Some metals can be pounded or pressed into various shapes or stretched very thinly without breaking. Others conduct electricity well.

• Often two or more metals are used to form alloys, which combine the most desirous properties of the metals used to make them.

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Mineral Resources and Their Uses

Section 1 Minerals and Mineral ResourcesChapter 16

Buildings

Roads

Bridges

Concrete

Extract minerals – like iron (Fe) to make steel

Toothpaste

Salt

Sandpaper

Decorations

Jewelry

1. Why is it important to have a basic understanding of the rock cycle?

Rocks contain clues about the environment. Helps us understand the formation of the earth.

2. RockAny solid mass of minerals or mineral-like matter

3. Do most rocks occur as one mineral or as a mixture of minerals?

4. Some rocks are made of non-mineral material, can you name one?

Coal - begins as layers of plant matter accumulate at the bottom of a body of water. For the process to continue the plant matter must be protected from biodegradation and oxidization, usually by mud or acidic water. This trapped atmospheric carbon in the ground in immense peat bogs that eventually were covered over and deeply buried by sediments under which they metamorphosed into coal. Over time, the chemical and physical properties of the plant remains (believed to mainly have been fern-like species antedating more modern plant and tree species) were changed by geological action to create a solid material.

Coal, a fossil fuel, is the largest source of energy for the generation of electricity worldwide.

5. Explain the rock cycle.A continuous process that causes rock to change from one form to another

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The Rock Cycle is a group of changes, this change does not necessarily have to be a chemical change. Igneous rock can change into sedimentary rock or into metamorphic rock. Sedimentary rock can change into metamorphic rock or into igneous rock.Metamorphic rock can change into igneous or sedimentary rock. Almost all of rock today that we have on earth is made up of all the same stuff as the rocks that dinosaurs and other ancient life forms walked, crawled, or swam overWhile the stuff that rocks are made of has stayed the same, the rocks themselves, have notOver time rocks are recycled into other rocksMoving tectonic plates are responsible for destroying and forming many types of rocks

6. List the 3 types of rocks

Igneous rock forms when magma cools and makes crystals. Magma is a hot liquid made of melted minerals. When magma pours onto the earth’s surface it is called lava. The minerals can form crystals when they cool. Igneous rock can form underground, where the magma cools slowly. Or, igneous rock can form above ground, where the magma cools quickly. The crystals grow together and form one igneous rocks.

7. Igneous Rocks

8. What kind of igneous rocks form when molten lava cools and hardens?

Extrusive = forced out while molten through cracks in the earth's surface

9. What is the Latin word that the word igneous comes from and what does it mean? ignis = fire

10. Intrusive Igneous RocksForm from magma below the earth’s surface

11. Extrusive Igneous RocksFormed by lava on the Earth’s surface

12. What is the difference between magma and lava?

Magma = molten rock below the earth’s surface

Lava = molten rock flowing on the earth’s surface

13. What are the 8 elements that make up magma?

Silicon, oxygen, aluminum, iron, calcium, sodium, potassium, magnesium

14. In what ways are the two rocks similar?

Look at the granite rock (A on age 71) and the rhyolite rock (B on page 71)

Granite Rhyolite

Both are from melted rock

Their composition is the same

15. In what ways are the two rocks different?Granite Rhyolite

Granite – coarse texture, made from magma

Rhyolite – fine texture, made from lava

16. What causes the two rocks to be different?Granite Rhyolite

Granite – Slow cooling below the earth’s surface

Rhyolite – Quick cooling on the earth’s surface

17. Why do you think some rocks are heavier than others?

Some are denser – less air space between particles

Which rock would have greater density?

Pumice Granite

Classifying Rocks

Rocks can be classified, or put into groups with similar characteristics, by looking at the rocks texture, mineral composition, and color.

18. What is texture?The size, shape, and pattern of the rock’s grain

(nice)

Glassy

The minerals that make up the different parts of a rock

19. Composition (what’s it made of?)

Examples:QuartzFeldsparMagnesiumIron

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Rock ColorThe apparent color of the rock, on the inside and the outside

Metamorphic rocks are rocks that have "morphed" into another kind of rock. These rocks were once igneous or sedimentary rocks. How do sedimentary and igneous rocks change? The rocks are under tons and tons of pressure, which fosters heat build up, and this causes them to change. If you exam metamorphic rock samples closely, you'll discover how flattened some of the grains in the rock are.

Rock divisions occur in three major families based on how they formed: igneous, sedimentary, and metamorphic. Each group contains a collection of rock types that differ from each other on the basis of the size, shape, and arrangement of mineral grains.Just remember 3 types of rocks=3 divisions. (igneous, sedimentary, and metamorphic)

When classifying a rock sample geologists observe the rock’s color and texture and determine its mineral composition.Texture: the size, shape, and pattern of the rock’s grain.Color: the apparent color of the rock, on the inside and the outside.Mineral composition: The minerals that make up the different parts of a rock.

Texture: Grain SizeOften, the grains in a rock are large and easy to see. Such rocks are said to be coarse-grained. In other rocks, the grains are so small that they can only be seen with a microscope. These rocks are said to be fine-grained. Notice the difference in texture between the fine-grained slate and the coarse-grained diorite to the right.

Texture: Grain Shape• The grains in a rock vary widely in shape• Some grains look like tiny particles of fine sand• Others look like small seeds or exploding stars• In some rocks, such as granite, the grain results from the

shapes of the crystals that form the rock• In other rocks, the grain shape results from fragments of

other rock• These fragments can be smooth and rounded, like the

fragments in conglomerate, or they can be jagged, like the fragments in breccia

• You can compare conglomerate and breccia one the next slide

Texture : Grain Pattern• The grains in a rock often form patterns. Some

grains lie in flat layers that look like a stack of pancakes.

• Other grains form wavy, swirling patterns. Some rocks have grains that look like rows of multicolored beads, as in the sample of gneiss shown above.

• Other rocks, in contrast, have grains that occur randomly throughout the rock.

Different Types of Texture

Fine-Grained, Coarse-Grained, Rounded Grain, Jagged Grain, Nonbanded, Banded

INTRUSIVE IGNEOUS ROCKS – When igneous rocks are formed by magma that cools BENEATH Earth’s surface, they are called intrusive igneous rocksEXTUSIVE IGNEOUS ROCKS – When igneous rocks are formed by LAVA ON Earth’s surface, they are called extrusive igneous rocks

2 Types of Igneous Rocks

• The process by which sediment becomes sedimentary rock

• 1st step : erosion• 2nd step : deposition• 3rd step : compaction• 4th step : cementation

Lithification

Sedimentary Rocks : ErosionDestructive forces are constantly breaking up and wearing away all the rocks on Earth’s surfaceThe forces include heat and cold, rain, waves, and grinding iceErosion occurs when running water or wind loosens and carry away the fragments of rock.

Sedimentary Rocks: Deposition  Eventually, the moving water or wind slows and deposits the sediment. If water is carrying the sediment, rock fragments and other materials sink to the bottom of a lake or ocean. Deposition is the process by which sediment settles out of the water or wind carrying it. After sediment has been deposited, the processes of compaction and cementation change the sediment into sedimentary rock. In addition to particles of rock, sediment may include shells, bones, leaves, stems, and other remains of living things. Over time, any remains of living things in the sediment may slowly harden and change into fossils trapped in the rock.

Sedimentary Rocks: Compaction At first the sediments fit together loosely. But gradually, over millions of years, thick layers of sediment build up. These layers are heavy and press down on the layers beneath them. Then compaction occurs. Compaction is the process that presses sediments together. Year after year more sediment falls on top, creating new layers. The weight of the layers further compacts the sediments, squeezing them tightly together. The layers often remain visible in the sedimentary rock.

 While compaction is taking place, the minerals in the rock slowly dissolve in the water. The dissolved minerals seep into the spaces between particles of sediment. Cementation is the process in which dissolved minerals crystallize and glue particles of sediment together. It often takes millions of years for compaction and cementation to transform loose sediments into solid sedimentary rock.

Sedimentary Rocks: Cementation

Point A: water or wind deposits sedimentsPoint B: The heavy sediments press down on the layers beneathPoint C: Dissolved minerals flow between the particles and cement them together

Sedimentary Transformations

Metamorphic Rock Pictures

Granite, Gneiss, Shale, Slate, Sandstone, and Quartzite are good examples of metamorphic rocks.

Bet Cha’ Weren’t Expecting A….POP QUIZ!!!!!*1. What are the three types of rock?2. Which type of rock has been formed by

magma or lava?3. What do we classify rocks by?4. How do sedimentary rocks form (in order)?5. Metamorphic rocks are rocks that have

?(fill in the blank)6. What is the process of sediments forming a

sedimentary rock? 7. What does “ignis” mean in the word igneous?

*Answers are on next slide!

ANSWERS!!!!1. Igneous, Sedimentary, and Metamorphic2. Igneous3. Texture, Color, and Mineral Composition4. Erosion, Deposition, Compaction, Cementation5. Morphed6. Lithification7. “ignis” means fire

www.dlese.com

Earth Science TextbookGoogle Images ( I KNOW THIS DOESN’T COUNT IM JUST TELLING YOU!!)http://www.rocksandminerals.com/rockcycle.htm

Sedimentary rocks form from particles deposited by water and windIf you have ever walked along a beach (which I am sure you have) you may have noticed tiny sand grains, mud, and pebbles.These are some sediments that eventually form into sedimentary rocksSedimentary Rocks can form in 4 ways by:

ErosionDepositionCompactionCementation