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

http://yourgemologist.com/crystalsystems.html

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