A pale to medium violet pigment originally composed of cobaltous arsenate. Cobaltous arsenate occurs in nature as cobalt bloom or erythrite; it was synthetically produced in 1880 and became an important permanent, violet pigment for paints, glass, glazes, and enamels. It is now rarely used because of its toxicity, generally substituted with deep cobalt violet or cobaltous ammonium phosphate. (en)