heavy, dark sulfosalt mineral, a silver and germanium sulfide (Ag₈GeS₆), in which the element germanium was discovered (1886). It is a relatively scarce mineral found in sulfide veins in Germany and in Bolivia. It forms a solid solution series with canfieldite in which tin replaces germanium in the crystal structure, which belongs to the isometric system. For detailed physical properties, see sulfosalt (table).