Barium borate Barium borate Barium borate is an inorganic compound, a borate of barium with a chemical formula BaBO or Ba(BO). It is available as a hydrate or dehydrated form, as white powder or colorless crystals. The crystals exist in the high-temperature α phase and low-temperature β phase, abbreviated as BBO; both phases are birefringent, and BBO is a common nonlinear optical material. Barium borate exists in two major crystalline forms: alpha and beta. The low-temperature beta phase converts into the alpha phase upon heating to 925 °C. β-Barium borate (BBO) differs from the α form by the positions of the barium
Sterling silver Royal Mint in 1843. It bears the royal stamp "ENRI. REX" ("King Henry") but this was added later, in the reign of Henry III. The first legal definition of sterling silver appeared in 1275, when a statute of Edward I specified that 12 Troy ounces of silver for coinage should contain 11 ounces pennyweights of silver and pennyweights of alloy, with 20 pennyweights to the Troy ounce. This is (not precisely) equivalent to a millesimal fineness of 926. In Colonial America, sterling silver was used for currency and general goods as well. Between 1634 and 1776, some 500 silversmiths created