GEOLOGY LAB QUIZ #1 ROCKS

Pyrite

Metallic luster, shiny gold

color, cubic crystals, dark

streak, heavy (dense)

Galena

Metallic luster, silver
color, heavy (dense), 3
directions of cleavage
at 90 degrees

Talc

Pearly white to pale
green, can be
scratched with a
fingernail, soapy feel

Garnet

Greenish yellow, 12-
sided (dodecahedral)
crystals, scratches
glass

Augite

dark green to black

Calcite

Clear to white, 3

directions of cleavage not

at 90 degrees, fizzes in

acid

Halite

taste like salt

Quartz

Clear, can have prismatic

crystal (hexagonal),

scratches glass, no

cleavage (fracture)

Sulfur

Yellow, smells like eggs,

no cleavage

Gypsum

White, striated, can be

scratched with a

fingernail

Olivine

Glassy luster, lime
green color

Hematite

Reddish brown streak,
metallic luster, silver
color (see also reddish
version)

Biotite Mica

Black-gold, 1 direction
of cleavage

Muscovite

Silvery grey, 1 direction
of cleavage (peels into
sheets), scratch with
fingernail

Magnetite

Magnetic, black, dull
but (metallic luster on
fresh surface), dense,
dark streak

Potassium Feldspar

Pink color, striations, 2
directions of cleavage
at 90 degrees, can
scratch glass

Graphite

Dull metallic luster,
silver grey streak,
greasy feel, writes on
paper, low density

Kaolinite

Soft, powdery

appearance, sticks to

tongue (don’t!).

Plagioclase Feldspar

Whitish blue, two
directions of cleavage
at 90 degrees,
scratches glass

Corundum

Dark red color, can
scratch glass and all
the other minerals,
hexagonal crystals

Copper

blackish-green
corrosion; metallic
luster

Pyroxene

Black-green color, two
directions of cleavage
at 90 degrees, white
streak