Acanthite | |
Chemical Formula |
Ag2S |
Species |
Sulfides |
Crystal System |
Monoclinic |
Mohs Scale |
2 |
Specific Gravity |
7.20-7.22 |
Color |
Iron-black |
Streak |
Black |
Luster |
Metallic |
Diaphaneity |
Opaque |
Cleavage |
None Observed |
Fracture |
Sub-Conchoidal |
Crystal Habit:Primary crystals rare, prismatic to long prismatic, elongated along , may be tubular; massive. Commonly paramorphic after the cubic high-temperature phase (“argentite”), of original cubic or octahedral habit | |
Geological Setting:A common silver species in moderately low-temperature hydrothermal sulphide veins, and in zones of secondary enrichment. Widespread in silver deposits. Localities for fine primary and paramorphic crystals include: Jáchymov (St Joachimsthal), Czech Republic [TL]; In Germany, at Freiberg, Schneeberg, Annaberg, and Marienberg, Saxony; and from St Andreasberg, Harz. In Mexico, large paramorphs from Arizpe, Sonora; In the Rayas and other mines at Guanajuato; And from many mines in Zacatecas, Chihuahua, etc; In the USA, at Butte, Silver Bow Co., Montana; Tonopah, Nye Co. and the Comstock Lode, Virginia City, Storey Co., Nevada; From various mines at Cobalt, Ontario, Canada; At Cha?arcillo, south of Copiapó, Atacama, Chile. |