Mineral Identification Key
Directions: Observe and test each of your mineral samples and use their properties to narrow down
your choices. Read the key from left to right in order to correctly identify the mineral name.
Cleavage
Hardness > 5

Cleavage in 2 directions @ 90˚; White, pink, or tan-colored;
H = 6…………………………………………….ORTHOCLASE FELDSPAR

Any color; Crystals form is hexagonal (if present); Vitreous
(glassy) luster; transparent to translucent; H = 7
o White or colorless………….………QUARTZ
o Pink………………………………ROSE QUARTZ
o Black or grey………..……SMOKY QUARTZ
o Purple……………………………….AMETHYST

Vitreous luster; Shades of greenish blue; Concoidal
fracture sometimes visible (hard to see); Sandy texture;
H = 6 – 7 ……….…………………………………………..………….OLIVINE

Cleavage in 3 directions @ 90˚; Colorless to white; Salty
taste; H = 2……….…………………………………………..………..HALITE

Cleavage in 3 directions, forming parallelogram shaped
crystal; Colorless or white; Vitreous or pearly………CALCITE

Cleavage: one definite plane, two poor; White to
transparent; small pieces flexible; Fibrous, silky luster;
H = 2……….…………………………………………..………..….. GYPSUM

One perfect cleavage plane; Colorless to light bronze; Thin
sheets are transparent, elastic; H = 2.5…MUSCOVITE MICA

One cleavage plane; White to yellowish or grey; White
streak; High density; Pearly to dull luster; H = 3……. BARITE

One cleavage plant (not easily visible); Soapy feel; White to
grey; H = 1…….……….…………………………………………..……..TALC

Cleavage in 8 directions (octahedral crystals); White,
yellow, purple or green; H = 4………………………..…..FLUORITE

Uneven fracture; Chalky white; White streak;
H = 1-2………………………………………………….KAOLINITE
Dull to resinous luster; Bright yellow color; White streak;
Noticeable odor H = 1.5 – 2.5…………………………….….SULFUR
Fracture
Non-metallic
Light-colored
Cleavage
Hardness < 5
Fracture

Cleavage

Cleavage @ 60˚ & 120˚; Black in color; Pale green streak;
Rough, but shiny texture; H = 5 – 6……………HORNBLENDE

Two cleavage planes close to 90˚; Light to dark grey;
Sometimes shows striations……….PLAGIOCLASE FELDSPAR

Dark red to red-brown; Vitreous or resinous luster;
H = 6.5 – 7.5…………………………………………....…………GARNET
Gray to dark brown; Pearly or vitreous luster; hexagonal
crystals; H = 9 ……………………………………………CORUNDUM
Hardness > 5
Fracture

Non-metallic
Dark-colored
Cleavage

One perfect cleavage plane; Brown to black color; Thin,
elastic plates; H = 2.5……………….………..…….…BIOTITE MICA

Six cleavage planes (hard to see); Yellowish brown; White
to pale, yellow streak; Resinous; H = 3.5 – 4…..SPHALERITE

Yellow-brown to dark brown; Brown streak; Earthy
luster; Earthy smell; H = 1 – 5………………….……LIMONITE

Yellow to grey to white; Dull to earthy luster; Grey
streak; Uneven fracture; H = 1 – 3; Appears as small
spherical pieces in matrix……..…………..…………..BAUXITE
Hardness < 5
Fracture
Black Streak
Metallic
Luster
Silver-grey
or dark-red
streak

Black or dark grey; No cleavage; High density; Magnetic (attracts iron);
H = 5.5 – 6.5 ………………………..……………………………..………………………..……MAGNETITE

Perfect cubic cleavage ( 3 planes @ 90˚; Very shiny, silvery grey; Grey streak;
Very high density; H = 2.5 – 3………………………....…………………………...…………GALENA
Green-black
Streak

No cleavage; Cubic or octahedral crystals; Golden color; Brittle;
Sometimes forms in cubic crystals; H = 6.5………………………….PYRITE

Greenish to coppery yellow; Duller than pyrite; H = 3.5 – 4
………………………….………………………….……………….………CHALCOPYRITE

Dark grey and shiny like a pencil lead; Smudges easily on finger; One cleavage plane
sometimes visible; H = 1 ……….………..………………………..…………………………….GRAPHITE

Shiny, sparkly luster; Bright silvery scales; H = 4 – 6. ………………SPECULAR HEMATITE

Very dull, silvery grey metallic luster; Uneven fracture; Mottled grey and dark red
color; high density; H = 4 – 6. ………………………………………..…………MASSIVE HEMATITE