Iron Sulfides

Abstract

Iron sulfides are generally quoted as minor magnetic minerals and the interest of paleomagnetists for this family of minerals progressively developed only during the last 10 – 15 years. This was due partly to the fact that their occurrence was originally believed to be restricted to peculiar geological environments (i.e. sulfidic ores, anoxic sulfate-reducing sedimentary environments) and partly to their metastability with respect to pyrite (FeS2), which is paramagnetic. Magnetic iron sulfides were therefore not expected to carry a stable remanent magnetisation and to survive over long periods of geological time in sedimentary environments. However, their occurrence as main carriers of a remanent magnetisation stable through geological times has been increasingly reported in recent years from a large variety of rock types, primarily as a result of more frequent application of magnetic methods to characterize the magnetic mineralogy in paleomagnetic samples. The recognition of the widespread occurrence of magnetic iron sulfides as stable carriers of natural remanent magnetisations in rocks propelled specific researches on their fundamental magnetic properties.