Mineralogical Study on Bacterial Magnetite

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Much interests have been focussed on biogenic magnetites not only biologically, technologically, medical sciences but also from the aspect of earth science contaning mineralogy. They are related to geomagnetism, evolution of life, environmental change in the early stage of the earth history. However, mineralogical studies have been rare till now on. In this study, we carried out mineralogical caharacterization of biogenic magnetites both from deep sea sediments(western Pacific Ocean and Japan Sea) and from living bacteria in Niigata Region. The results showed the followings : Deep Sea sediments contain pretty large amounts of biogenic magnetite. Biogenic magnetite was found for the first time from the Japan Sea. Various shapes of the magnetite were found. The Japan Sea sediments often contain more predominant tear drop types that the other types. The crystallographic elongation direction of the tear drop type were determined by TEM.They are often a-directions. The other mineralogical characteristics were determined. Examining living bacteria, mascagnite grain was found for the first time, Mascagnite is (NH_4)_2SO_4. They may be related metabolic products although the detail is not kyown.