Silver minerals include argentite and native silver. Minor arsenopyrite, marcasite, chalcopyrite, valleriite, proustite, polybasite and argentite also occur. The metallic ore minerals are mostly in sulphides, such as galena, sphalerite, enargite, and argentite. In the Comstock lode in Nevada massive stephanite and argentite are important ores of silver. Acanthite and argentite are the principal silver ore minerals. Argentite belongs to the galena group. Argentite is the stable form above that temperature. The International Mineralogical Association has decided not to reject argentite as a proper mineral.