Rocks: Mineral Mixtures Chapter 4
Dec 16, 2015
Rock CycleRock Cycle
Process in which one rock type changes into another rock type
Three Rock types:IgneousSedimentaryMetamorphic
Weathering and Erosion– Forms clasts or grains
DepositionCompacting and Cementing
– Glues rock together, usually in layers
Rock Cycle Mechanics: SedimentaryRock Cycle Mechanics: Sedimentary
Igneous MechanicsIgneous Mechanics
MeltingMagma under crustLava on Earth’s surface
Cooling Solidification
Rock ClassificationRock Classification
Color Composition
Minerals determine make-up of the rock Texture
Size and shape of grains– Fine– Medium – Coarse
Igneous RocksIgneous Rocks Rock formed from cooling magma or lava Three ways rock can melt:
Increase in temperatureRelease of pressureComposition
– 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”
CompositionComposition
FelsicLightweightLight in colorHigh silica
MaficDark in colorDense or heavyLow silica
TextureTextureIntrusive
Coarse grainedCools below crustCools slowly
ExtrusiveFine grainedCools above the crustCools quickly
Composition and TextureComposition and TextureCoarse-Grained Fine-Grained
Felsic:High silica
Granite Rhyolite
Mafic:Low silica
Gabbro Basalt
Sedimentary rocksSedimentary 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
Composition of Sedimentary rocks
Composition of Sedimentary rocks
Classified by way it forms Classifications:
ClasticChemicalOrganic
Clastic SedimentaryClastic Sedimentary
Made of fragments of other rocks Grain size helps identify rock
Coarse = ConglomerateMedium = Sand/siltstoneFine = Shale
Chemical SedimentaryChemical Sedimentary
Forms from solutions of minerals and water Precipitation dissolves minerals Rock forms through evaporation, or will
crystallize out of water solution
Organic SedimentaryOrganic Sedimentary
Comprised of the remains of once living organisms
Some limestone is formed this way Comprised of Calcium Carbonate
Reacts with acid
Sedimentary Rock StructureSedimentary Rock Structure
StratificationLayering of sedimentary rock
Layers are called Strata
Metamorphic RocksMetamorphic 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
Metamorphism TypesMetamorphism Types Contact Rock does not melt, but
cooks into new rock
Regional Enormous pressure Due to crust colliding Found near continental
formations (mountains)
CompositionComposition
Conditions allow for minerals to combine making new rocks
Some minerals will only form at certain pressure and heat ranges