Hematite

Fe₂O₃

high specific gravity

red-brown streak

Bauxite

Al(OH)₃

Magnetite

Fe₃O₄

very magnetic

black streak

Corundum

Al₂O₃

hardness = 9

hexagonal habit

Limonite

FeOOH*nH₂O

yellow-brown streak

earthy luster

Cassiterite

SnO₂

high specific gravity

distinctive brown color

possible tetragonal prisms

Fluorite

CaF₂

hardness = 4

octahedral cleavage

Goethite

FeOOH

brown streak

hardness = 5-5.5

botryoidal habit

Chromite

FeCr₂O₄

Ilmenite

FeTiO₃

black streak

platy habit

weak magnetism

Halite

NaCl

salty taste

cubic cleavage

Cinnabar

HgS

red streak

hardness = 2-2.5

Pyrite

FeS₂

isometric

metallic gold color

green-black streak

Molybdenite

MoS₂

basal cleavage

hardness = 1-1.5

Copper

Cu

hackly fracture

penny colored

Chalcopyrite

CuFeS₂

tarnish

yellow colored gold

tetragonal

Chalcocite

Cu₂S

black sooty tarnish

hardness = 2.5-3

Sulfur

S

smells like ass

yellow vitreous luster

Sphalerite

ZnS

basal cleavage

brown/yellow streak

Graphite

C

hardness = 1-2

resinous luster

Galena

PbS

cubic cleavage

high specific gravity

steel gray streak

Arsenopyrite

FeAsS

garlic odor when crushed

prismatic habit

Pyrrhotite

Fe_1-xS

bronze color

softer than pyrite 3.5-4.5

Azurite

Cu₃(CO₃)₂(OH)

blue color

blue streak

effervesces

Anhydrite

CaSO₄

cubic cleavage

hardness = 3-3.5

Siderite

FeCO₃

effervesces (powdered)

high specific gravity

brownish color

Aragonite

CaCO₃

effervesces vigorously

denser than calcite

Malachite

Cu₂CO₃(OH)₂

green color

green streak

effervesces

Dolomite

CaMg(CO₃)₂

effervesces (powdered)

hardness = 3.5-4

Calcite

CaCO₃

effervesces

hardness = 3

rhombohedral cleavage

Rhodochrosite

MnCO₃

pink to red color

effervesces (powdered)

rhombohedral cleavage

Witherite

BaCO₃

effervesces vigorously

higher specific gravity than aragonite

Apatite

Ca₅(PO₄)₃(OH,F,Cl)

adamantine luster

hexagonal crystals

hardness = 5

Gypsum

CaSO₄*2H₂O

hardness = 2

fibrous texture

Barite

BaSO₄

high specific gravity

tabular crystals