Tetradymite

General Information: Chemical Formula:Bi2Te2S Composition:(Molecular Weight = 705.23 gm)Bismuth 59.27 % BiTellurium 36.19 % TeSulfur 4.55 % S  Empirical Formula: Bi2Te2S Name Origin:From the Greek, tetradymos, "fourfold."Physical Properties: Cleavage:[0001] Perfect Color:steel gray or yellow gray. Density:7.2 - 7.9, Average = 7.55 Diaphaniety:Opaque Habits:Lamellar - Thin laminae producing a lamellar structure., Granular - Generally occurs as anhedral to subhedral crystals in matrix., Pseudo Hexagonal - Crystals show a hexagonal outline . Hardness:1.5-2 - Talc-Gypsum Luminescence:None. Luster:Metallic Streak:steel grayMore details...