Pound (mass) for the weight of certain precious metals, especially in the trade; these are normally quoted just in ounces (e.g. "500 ounces") and, when the type of ounce is not explicitly stated, the troy system is assumed. Historically, the pound sterling was a Tower pound of silver. In 1528, the standard was changed to the Troy pound. The avoirdupois pound, also known as the wool pound, first came into general use c. 1300. It was initially equal to 6992 troy grains. The pound avoirdupois was divided into 16 ounces. During the reign of Queen Elizabeth, the avoirdupois pound was redefined as
Troy weight g, 12 oz t), while an avoirdupois pound is approximately 21.53% heavier at 7 000 grains (≈ 453.59 g). One troy ounce (oz t) is equal to grams. Also equal to avoirdupois ounces, exactly , or about 10% larger. The pennyweight symbol is "dwt". There are 24 grains in 1 dwt, and 20 dwt in one troy ounce. Because there were 12 troy ounces in the old troy pound, there would have been 240 pennyweights to the pound—the basis of the fact that the old British pound sterling of currency contained 240 pence. (However, prior to 1526, English pound sterling