Category Sulfosalt minerals Space group C2/c | Strunz classification 2.GB.15 | |
 | ||
Formula(repeating unit) [(Ag,Cu)6(Sb,As)2S7][Ag9CuS4] Crystal system Monoclinic and trigonal polytypes Crystal class Prismatic (2/m)(same H-M symbol) | ||
Polybasite is a sulfosalt mineral of silver, copper, antimony and arsenic. Its chemical formula is [(Ag,Cu)6(Sb,As)2S7][Ag9CuS4].
It forms black monoclinic crystals (thin, tabular, with six corners) which can show dark red internal reflections. It has a Mohs hardness of 2.5 to 3. It is found worldwide and is an ore of silver. The name comes from the number of base metals in the mineral.
References
Polybasite Wikipedia(Text) CC BY-SA