It forms a series with arsenopyrite (FeAsS). It occurs in a wide range of minerals including arsenopyrite, pyrite and magnetite. Various transition group metals can substitute for iron in arsenopyrite. Primary minerals are chalcopyrite, pyrrhotite and arsenopyrite. Chalcopyrite occupies later fractures which intersect massive arsenopyrite. This odor can be detected on striking arsenide minerals such as arsenopyrite with a hammer. The veins commonly contain tourmaline, topaz, fluorite, apatite, wolframite, molybdenite, and arsenopyrite. Most arsenic is prepared by heating the mineral arsenopyrite in the presence of air. It is often found associated with arsenopyrite (FeAsS) from which it is hard to distinguish. The gold is usually accompanied with arsenopyrite. Skarn deposits contain magnetite, iron pyrite, arsenopyrite, chalcopyrite, sphalerite and galena. Other sulfide minerals occurring with these deposits include pyrite, arsenopyrite and realgar. The bacteria dissolved the sulphides like pyrite and arsenopyrite and thus revealed the native gold. An illustrative mineral is arsenopyrite (FeAsS), which is structurally related to iron pyrite. Minor arsenopyrite, marcasite, chalcopyrite, valleriite, proustite, polybasite and argentite also occur.