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Siderite is a mineral composed of iron carbonate (FeCO3). It takes its name from the Greek word σίδηρος sideros, “iron”. It is a valuable iron mineral, since it is 48% iron and contains no sulfur or phosphorus. Both magnesium and manganese commonly substitute for the iron. Siderite has Mohs hardness of 3.75-4.25, a specific gravity of 3.96, a white streak and a vitreous lustre or pearly luster. Its crystals belong to the hexagonal system, and are rhombohedral in shape, typically with curved and striated faces. It also occurs in masses. Color ranges from yellow to dark brown or black, the latter being due to the presence of manganese, sometimes called manganosiderite. (source: Wikipedia). Return to List Back to Michael's Hobbies page Back to Michael Marcotte's HomePage