Both mackinawite and greigite are metastable compared to pyrite and pyrrhotite.Ībove all, the sulfides are the most important group of ore minerals because they are responsible for the concentration of a wide range of metals as mineable deposits. Formerly known as ‘amorphous iron sulfides’, they are now known to be mackinawite (tetragonal FeS) and, to a lesser extent, greigite (Fe 3S 4). The very fine particulate iron sulfides found in reducing environments beneath the surfaces of some sediments and soils are also important. These five are pyrite, pyrrhotite, galena, sphalerite and chalcopyrite, and it is the iron sulfides (pyrite and pyrrhotite) which are dominant. Several hundred sulfide minerals are known, but only five are sufficiently abundant accessory minerals to have been categorized as ‘rock forming’ (Bowles et al. They generally contain pyramidal TS 3 groups in their structures. The sulfosalts are a special group of the sulfide minerals that have a general formula A mT nX p and in which the common elements are A = Ag, Cu, Pb T = As, Sb, Bi X = S. The definition is commonly widened to include minerals in which the anion is As or Sb, sometimes together with S, and to include Se and Te minerals.
Sulfide minerals are compounds in which sulfur is combined as an anion with a metal (or semi-metal) cation or cations. Keywords: metal sulfides, crystal structures, paragenesis, surface chemistry, biogeochemistry Introduction
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