Polybasite
From Wikipedia, the free encyclopedia
Polybasite is a sulfosalt mineral of silver, copper, antimony and arsenic. Its chemical formula is (AgCu)16(SbAs)2S11.
It forms black hexagonal crystals 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.