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GEOLOGY MIDTERM REVIEW
HEMATITE
• Red streak• Metal• Heavy
magnetite
• Magnetic• Heavy• Metallic• Black streak
plagioclase
• Scratches glass• White• 2 directional cleavage
Olivine
• Green- always
• Hard
• Crystalizes at highest temp.– First to form from a melt
gypsum
• Soft 1-2
• Clear= selenite
• Opaque= alabaster
• Chalky feel
pyrite
• Fool’s gold• Metal
halite
• Salty• 3= 90 cleavage• soft
galena
• 3= 90 cleavage• Metal • heavy
hornblende
• Black- always
• Hard- 5-6
• Two directional cleavage
talc
• Softest mineral
• Greasier feel than gypsum
calcite
• Fizzes• 3 ≠ 90 cleavage• Double refraction• Soft• Main mineral in
limestone and marble
K-feldspar
• Pink• Scratches glass• 2= 90 cleavage
muscovite
• Flakey- 1 directional cleavage
• Light in color
corundum
• Extremely hard= 9
• May have hexagonal crystals
• Red= ruby
• Blue= sapphire
quartz
• Most common mineral• Scratches glass• NMV• Hexagonal crystals
• Rock crystal- tpt• All others- tlt
fluorite
• Soft• Many colors; purple
and green • 4 directional cleavage
graphite
• Pencil “lead”• Soft metal
biotite
• Dark color
• One directional cleavage
• Part of the mica family
chalcopyrite
• “bronzier” than pyrite– More of an orange color
• Contains copper
• Black streak
IGNEOUS ROCKS
GRANITE
• Intrusive igneous• Cooled slowly• Felsic• Has quartz, plag.,
biotite, K-feld, hornblende
• Formed underground (dikes, sills, batholiths)
Andesite
• Extrusive
• intermediate
• Usually porphyritic
• Composite volcanoes
pumice
• Felsic• Extrusive• Composite volcanoes• vesicular
basalt
• Extrusive• Mafic• Shield volcanoes• From runny lava flows
• Pahoehoe and Aa are types of basalt
gabbro
• “black granite”• Intrusive• Mafic• Formed underground
(dikes, sills, batholiths)
• Granite’s mafic cousin
scoria
• Vesicular• Mafic• From cinder
volcanoes• Pumice’s “mafic
cousin”
obsidian
• Felsic (even though dark)
• 99% quartz
• Conchodial fracture
• Cools on top of felsic lava flow
periodotite
• Mafic
• intrusive\
• Contains olivine
rhyolite
• Felsic
• Composite lava flows
SEDIMENTARY
Crystalline limestone
• Fizzes• Chemical precipitate• Forms in deep ocean• From dissolved shells
fossiliferous
Rock gypsum
• Evaporite• soft
shale
• Fine clastic• From mud
sandstone
• Gritty• From beach/desert• clastic
coal
• Bioclastic• From swamps• Organic• lightweight
chalk
• Soft
• Bioclastic (forminifera)
• fizzes
arkose
• High in K-feldspar
• Sandstone
• clastic
coquina
• Bioclastic• Made of shells• Forms near reefs
• Conglomerate• Fast moving river
• Breccia• Alluvial fan
• flint • Chert
Metamorphic
slate
• Metamorphosed shale
• Foliated• Parent rock: shale
Gneiss
• Banded (striped)• Foliated• Parent rock- granite
marble
• Can be many colors• Metamorphosed
limestone• Not foliated• Will fizz (calcite)
Quartzite
• Metamorphosed sandstone
• Non foliated• Will scratch glass• Any color
Schist
• Foliated• Highly reflective• May have garnets
metaconglomerate
OTHER STUFF
Solution Mining
Silicate structureswhy common?
1 carat= .2 grams
• 50 cts= grams
• 25 grams= carats
Geodes
• Form from precipitation of quartz in a hollow opening
Gold %
• Divide by 24 (pure gold)
Rock cycle
viscosity
• Rhyolite• High viscosity (thick)• Explosive eruption
• Basalt• Low viscosity (runny)• Quiet eruptions
lithification
• Precipitation
• Evaporation
• Cementation
• compaction
oxidation
dissolution
• Usually limestone• Acid rain• Forms
caves/sinkholes
caves
CLIMATE
• TROPICAL– Strong chemical
• DESERT– Slight mechanical
• POLAR– Slight mechanical
• MID LATITUDE (MI)– Strong chemical and mechanical
TYPES OF SOIL
• Sandy- drains fast
• Clayey- absorbs water; doesn’t let water pass through; poor for house foundations
• Loamy- best for plants
transgression
• Rise in sea level
regression
• Drop in sea level