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

5. Metamorphism Mechanics
Rock undergoes Heat and Pressure

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

7. Rock Classification Color Composition Texture
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 Mafic Lightweight Light in color High silica
Dark in color
Dense or heavy
Low silica

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

11. Composition and Texture
Coarse-Grained
Fine-Grained
Felsic:
High silica
Granite
Rhyolite
Mafic:
Low silica
Gabbro
Basalt

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

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
Regional Contact

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