Galena

Formula:  PbS

Origin of name:  Form Latin for lead ore

Crystal system:  Cubic

Crystal class:  4/m -3 2/m

Twinning:  On {111}, penetration or contact; on {114}, lamellar

Unit cell: a = 5.936 Ǻ

Colour:  Lead-gray

Diaphaneity:

Luster:  Bright metallic

Habit:  Crystals cubic, octahedral, or cuboctahedral, or tabular, skeletal, or reticulated; massive, cleavable; granular; fibrous

Hardness:  2.5

Specific gravity:  7.58

Cleavage:  1; {001} perfect

Tenacity:  Subconchoidal

Streak:  Lead-grey

Synonyms/varieties:  Galenite, bleiglanz

Comments:  Series with clausthalite