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,
Actual silver weight $15.00 per troy ounce, the intrinsic value of a pre-1965 Roosevelt dime would be: 0.072339075 × 15.00 = $1.085086125 ≈ $1.09. (Note that coin stores, pawn shops, and bullion retailers will not necessarily purchase coins from consumers at the intrinsic value because of the costs involved with selling such coins to companies that melt the coins, separate the constituent metals, and prepare the silver for resale.) Actual silver weight Actual silver weight, usually abbreviated ASW, refers to the weight of pure silver contained in a coin, measured in troy ounces. Coin collectors, individuals who invest in bullion coins, and others