The iron sulphide minerals: their chemistry and role in nature

Metal sulphides are a major group of ore minerals, and the iron sulphides are the most widely occurring of the sulphide minerals, found not only in sulphide ore deposits but also as accessory minerals in many common rocks. The situation regarding understanding of the structures, stabilities and phase relations of these materials is summarized with emphasis on the application of modern crystal chemical theories. Two processes discovered to be taking place at the present-day have done much to clarify sulphide formation. One is the generation of sulphide by the bacterial reduction of sulphate in anoxic bottom waters and sediments. The other is the expulsion into the oceans, in areas such as mid-ocean ridges, of hydrothermal fluids from which metal sulphides are directly precipitating. The iron sulphides could have played a central role in supplying energy and, perhaps, in catalysing reactions leading to the build-up of complex organic molecules in such a process. -from Authors