CHEMISTRY - Sb2S2O
CRYSTALLOGRAPHY - Triclinic (Pseudo monoclinic)
CRYSTAL GROWTH AND HABITS - Very elongate, lath shaped crystals; sometimes acicular.
COLOR AND OTHER OPTICAL PROPERTIES - Dark cherry red to almost black; reddish in thin pieces; translucent.
HARDNESS - 1 - 1.5
SPECIFIC GRAVITY - 4.68 - 4.69
LUSTER - Adamantine to sub metallic
STREAK - Brownish red
BREAKABILITY - Nearly perfect cleavage in one direction, sectile; thin splinters are somewhat flexible.
OCCURRENCE - As a secondary mineral in antimony deposits; as an alteration product of stibnite.
ASSOCIATED MINERALS - Stibnite, Antimony, Stibiconite
Mineral Name - From "kermes" (Persian gurmizg) for the trisulfate of red amorphous antimony.