Siderite Wikipedia
Siderite is a mineral composed of iron II carbonate FeCO 3 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 Zinc magnesium and manganese commonly substitute for the iron resulting in the siderite smithsonite siderite magnesite and siderite rhodochrosite solid solution series