Rhodochrosite: Manganese ore, gemstone, mineral specimen
Physical and Chemical Properties. Rhodochrosite has a variable chemical composition. It is a manganese carbonate, but the manganese is frequently replaced by iron, magnesium and/or calcium as shown in this formula: (Mn,Fe,Mg,Ca)CO 3.. These substitutions of other elements for manganese change the composition and alter the specific gravity, hardness, and color of the mineral.