VI. Class of Minerals

Carbonates are a group of minerals that have the carbonate anion group as their basic building unit, which most commonly forms compounds with calcium, magnesium, iron, manganese, zinc, copper, lead, or rare earth elements. Carbonate minerals are generally of low hardness, soluble in hydrochloric acid, and exhibit pronounced anisotropy in many physical properties due to the planar structure of the carbonate anion group. They are widespread in the Earth's crust, with the most important being calcite and dolomite, which form large monomineral rock masses of sedimentary origin—limestone and dolomite rocks.