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hemimorphite, a mineral from the group of zinc hydrosilicates; chemical composition, Zn4[Si2O7] [OH]2 ⋅ H2. Contains 67.5 percent ZnO.
Calamine crystallizes in the rhombic system. The crystals are usually small and found only in vacancies. Calamine is found most frequently in the form of crystalline crusts with a radiate-fibrous structure and in nodular and stalactite masses. The color is white, yellow, or greenish blue (from admixtures of iron and copper compounds). Hardness on the mineralogical scale, 4-5; density, 3, 400-3, 500 kg per cu m. The crystals show pyroelectric properties when heated. Calamine forms in the oxidation zone of lead and zinc deposits. Rich accumulations have been found in the USSR (eastern Transbaikal and central Kazakhstan) andabroad (Upper Silesia in Poland). It is used as an ore for obtain-ing zinc.