Biogenic magnetite in stromatolites. II. Occurrence in ancient sedimentary environments

In this paper we report the discovery of fossil bacterial, single-domain magnetite particles in ancient stromatolites. The biogenicity of the crystals was determined by the following criteria: (1) distinctive morphology and habit, (2) composition and (3) environment of deposition. Stromatolites ranging in age from the Middle Archean to Pleistocene, composed of both carbonate and chert, were analyzed for the presence of single-domain magnetite...