rocks and minerals quiz enst200

quartz

- SiO2

- hardness: *7, scratches glass*

- *conchoidal fractures*

- *vitreous (glassy)*

- no streak

- white/clear

- resistant to weathering

- found in granite and soils

orthoclase

- KAlSi3O8

- hardness: *6, scratches glass*

- *streaks white*

- *reddish/pinkish*

- reflective layers, vitreous

- common in acidic igneous rock and soil

plagioclase

- NaAlSi3O8-CaAl2Si2O8

- hardness: *6, scratches glass*

- "streaks colorless"

- vitreous to pearly

- white to gray

- *crystals formed in one direction*

- all have striations on the basal cleavage plate

muscovite

- KAl2(AlSi3O10)(OH)2

- *looks like plastic*

- colorless streak

- tiny sheets

- white/clear

- vitreous to pearly

biotite

- K(Mg,Fe)3AlSi3O10(OH)2

- *black thin sheets*

- pearly to vitreous

- black, brown, dark green

calcite

- CaCO3

- hardness: *3, scratched by steel nail*

- *white colorless*

- *rhombus-shaped crystals*

- streaks colorless

dolomite

- CaMg(CO3)2

- *pinkish white, greyish white*

- streaks colorless

- hardness: 3.5-4

apatite

- 3Ca3(PO4)2 Ca(F,Cl)2

- hardness: 5

- streaks white

- *vitreous*

- *green, may be brown*

olivine

- (Mg,Fe)2SiO4

- hardness: 6.5-7

- *conchoidal fractures*

- *olive, to greyish green, to brown*

- long prism crystals

- *granular*

hornblende

- Ca, Na, Fe, Mg, Al

- *black or dark green*

- hardness: 5-6

- *crystals are long prisms*

serpentine

- Mg6Si4O10(OH)8

- *greasy luster*

- *variegated green*

- hardness: 2-5

- grey with green inclusions and not shiny

hematite

- Fe2O3

- hardness: 5.5

- *streaks dark red*

- metallic

- bluish grey to red

limonite

- FeO(OH)*nH2O

- *streaks yellow brown*

- hardness: 5-5.5

- dark brown to black

- slight shine

pyrite

FeS2

- hardness: *6-6.5, scratches glass*

- *green to brownish black streak*

- *metallic*

- *brass yellow*

gypsum

- CaSO4 * 2H2O

- hardness: *2, can be scratched by fingernail*

- *vitreous, pearly to silky*

- white to colorless or grey

syenite

- igneous

- coarse

- light colored

- dull

- like granite but without quartz

- orthoclase, some quartz, biotite, hornblende

granite

- igneous

- light colored (white with black specs)

- large shiny specs

- colorless streak

- orthoclase, quartz, plagioclase, biotite, hornblende

rhyolite

- igneous

- fine grained

- pink and brown

- colorless streak

- weaker than glass

- orthoclase, quartz, plagioclase, biotite, hornblende

gabbro

- igneous

- coarse grained

- reflective

- dark

- colorless streak

- plagioclase, pyroxenes, hornblende, olivine

basalt

- igneous

- fine grained

- black

- dull

- sharp edges

- random fractures

- plagioclase, pyroxenes, hornblende, olivine

obsidian

- igneous

- glassy

- black

- sharp

- quartz, biotite, plagioclase, pyroxenes, hornblende

gneiss

- metamorphic

- somewhat coarse

- streaks of black throughout white

- shiny specs

- quartz, feldspar, micas, hornblende, pyroxenes

phyllite

- metamorphic

- fine grained

- uniform color

- streaks colorless

- thin sheets

- mica

schist

- metamorphic

- fine grained

- shiny metal specs

- black specs

- chlorite, talc, mica

marble

- metamorphic

- coarse grained

- dull shiny

- white (can be stained orange)

- scratches glass

- calcite, serpentine, dolomite

slate

- metamorphic

- fine grained

- dull black

- not as shiny as phyllite

- layers

- seldom visible

shale

- sedimentary

- fine grained

- streaks red

- reddish brown

- thin sheets

- dull

- quartz

sandstone

- sedimentary

- coarse grained

- sandy

- streaks sand

- quartz mainly, calcite, glauconite, gypsum

limestone (calcitic)

- sedimentary

- fine grained

- grey

- dull

- scratches glass

- random formations

- calcite

limestone (dolomitic)

- sedimentary

- feels dusty

- dull

- pale yellowish

- doesn't scratch glass

- dolomite

conglomerate

- sedimentary

- very coarse

- big crystal chunks

- scratches glass

- quartz