Pyrostilpnite

Formula: Ag₃SbS₃

Origin of name: from Greek for fire and shining

Crystal system: monoclinic

Crystal class: 2/m

Twinning: on {100}

Unit cell: a = 12.17 Å, b = 15.84 Å, c = 6.24 Å, b = 90.0°

Colour: red

Diaphaneity: 

Luster: adamantine

Habit: crystals tabular, forming flat rhombs, lath-like, sheaf-like aggregates that resemble stilbite

Hardness: 2

Specific gravity: 5.94

Cleavage: 1; {010} perfect

Tenacity: conchoidal, thin plates flexible

Streak: yellowish orange

Synonyms/varieties:

Comments: dimorphous with pyrargyrite