Barite

BaSO4. Soft mineral, usually white, frequently occurring in large tabular rhombic crystals, and also in uncrystalline ma es. Composition, barium sulphate. Sp. gr. 4.5. Known also as barytes or baryta, and, in England, as cawk. It is common with deposits of lead or silver ore. A brown stalactitic variety takes a handsome polish, resembling dark-colored marble. Bologna stone, from which Bologna phosphorus was prepared, was barite that became phosphorescent after heating with charcoal. Barite finds an extensive commercial use, chiefly as an adulterant of, or substitute for, white lead in pigments. In the U. S. the estimated yield is 28,000 tons annually, chiefly from Mo. and Va. Considerable quantities are imported from Germany. It is freed from iron by hydrochloric acid.