Cleavage

Other

Mineral

one

White, gray, apple green in color; pearly luster; greasy feel; may have a slight streak (see also table MT5)

Talc

Mg₃Si₄O₁₀(OH)₂

White in color; satiny or silky luster; fibrous fracture (see also table MT5)

Gypsum

CaSO₄ 2H₂O

Green, blackish green in color; dull, vitreous or pearly luster; may have a faint yellow streak; cleavage flakes are flexible

Chlorite

Hydrous Mg-Fe-Al silicate

Black, brownish black in color; vitreous luster; may have a faint black streak; cleavage surfaces are wavy; transparent; flexible and elastic

Biotite

Hydrous K-Mg-Fe-Al silicate

Colorless, silvery white, brownish silvery white in color; vitreous luster; transparent; flexible and elastic

Muscovite

Hydrous K-Al silicate

Two

Black in color; vitreous luster; may have a faint green-gray streak; two perfect cleavages with angles at 124 degrees and 56 degrees; splintery appearance

Hornblende

Hydrous Na-Ca-Mg-Fe-Al

Black, dark green in color; vitreous to dull in luster; imperfect cleavages at 90 degrees (see also table MT3)

Augite

Ca-Mg-Fe silicate

Three

Clear, gray, red in color; three perfect cleavages at 90 degrees; salty taste

Halite

NaCl

Clear, white, light gray in color; vitreous or pearly luster; brittle sheets; two of the cleavages are poor

Gypsum

CaSO₄ 2H₂O

Colorless, white in color; tabular or rose-like array of crystals; cleavages at 90 degrees

Barite

BaSO₄

Clear, white, possible other colors; vitreous luster; three perfect cleavages form a rhombus; reacts strongly to acid

Calcite

CaCO₃

Buff, gray, white, pinkish in color; small, rhombohedral crystals or massive; three cleavages not at 90 degrees but may be indistinct; reacts slowly with acid or not at all unless powdered (see also table MT5)

Dolomite

CaMg(CO₃)₂

Four

Purple, green, blue, yellow, clear in color; vitreous luster; perfect cleavage up to four directions; octahedral cleavage or may occur as cubic crystals

Fluorite

CaF₂