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Rocks: Mineral Mixtures Chapter 4. Rock Definition  Solid mixture of one or more minerals.

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Presentation on theme: "Rocks: Mineral Mixtures Chapter 4. Rock Definition  Solid mixture of one or more minerals."— Presentation transcript:

1 Rocks: Mineral Mixtures Chapter 4

2 Rock Definition  Solid mixture of one or more minerals

3 Rock Cycle  Process in which one rock type changes into another rock type  Three Rock types: Igneous Sedimentary Metamorphic

4  Weathering and Erosion –Forms clasts or grains  Deposition  Compacting and Cementing –Glues rock together, usually in layers Rock Cycle Mechanics: Sedimentary

5 Metamorphism Mechanics  Metamorphism Rock undergoes Heat and Pressure

6 Igneous Mechanics  Melting Magma under crust Lava on Earth’s surface  Cooling  Solidification

7 Rock Classification  Color  Composition Minerals determine make-up of the rock  Texture Size and shape of grains –Fine –Medium –Coarse

8 Igneous Rocks  Rock formed from cooling magma or lava  Three ways rock can melt: Increase in temperature Release of pressure Composition –Fluids and gases can lower melting point of rock  Rocks will freeze between 700 and 1,250 Water freezes at 0 degrees Celsius  Comes from Latin word for “fire”

9 Composition  Felsic Lightweight Light in color High silica  Mafic Dark in color Dense or heavy Low silica

10 Texture  Intrusive Coarse grained Cools below crust Cools slowly  Extrusive Fine grained Cools above the crust Cools quickly

11 Composition and Texture Coarse-GrainedFine-Grained Felsic: High silica GraniteRhyolite Mafic: Low silica GabbroBasalt

12 Igneous Structures  Volcanic necks  Pluton and Batholith  Lava flows and sills

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15 Sedimentary rocks  Rock that is formed when sediments are compacted and cemented together  Dissolved minerals in solution glue sediments together  Forms at or near the Earth’s surface  Sediment rocks form in layers known as strata

16 Sedimentary Rocks

17 Composition of Sedimentary rocks  Classified by way it forms  Classifications: Clastic Chemical Organic

18 Clastic Sedimentary  Made of fragments of other rocks  Grain size helps identify rock Coarse = Conglomerate Medium = Sand/siltstone Fine = Shale

19 Chemical Sedimentary  Forms from solutions of minerals and water  Precipitation dissolves minerals  Rock forms through evaporation, or will crystallize out of water solution

20 Organic Sedimentary  Comprised of the remains of once living organisms  Some limestone is formed this way  Comprised of Calcium Carbonate Reacts with acid

21 Sedimentary Rock Structure  Stratification Layering of sedimentary rock  Layers are called Strata

22 Metamorphic Rocks  Meta = Changed Morphos = Shape  Rock that forms when composition and texture of preexisting rock is changed by heat and pressure  Enlargement and rearrangement of grains  Change occurs deep underground (plate tectonics)  Two Common Types RegionalContact

23 Metamorphism Types  Contact  Rock does not melt, but cooks into new rock  Regional  Enormous pressure  Due to crust colliding  Found near continental formations (mountains)

24 Composition  Conditions allow for minerals to combine making new rocks  Some minerals will only form at certain pressure and heat ranges

25 Texture  Foliated  Mineral grains aligned due to pressure  Nonfoliated  Lacks mineral alignment  Commonly made of one or a few minerals


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