Coins of the pound sterling also became known as a "pound". (240 actual pennies, however, weighed only 5400 troy grains, known as tower pound, a unit used only by mints. The tower pound was abolished in the 16th century.) The silver penny remained the primary unit of coinage for about 500 years. The purity of 92.5% silver (i.e., sterling silver) was instituted by Henry II in 1158 with the "Tealby Penny" — a hammered coin. Over the years, the penny was gradually debased until by the 16th century it contained about a third the silver content of a proper troy 24 grain pennyweight. By 1915,
Troy weight troy relates to a dialect word troi (balance). Then troy weight is a style of weighing, like auncel or bismar weights, or other kindred methods. The troy weight then refers to weighing of small precious or potent goods, such as bullion and medicines. Troy ounces are still often used in precious metal markets in countries that otherwise use International System of Units (SI), except in East Asia. The People's Bank of China, in particular, which has never historically used troy measurements, has begun issuing Gold Pandas minted according to SI weights. The troy pound is 5 760 grains (≈ 373.24