Pre-1965 USA dimes, quarters & half dollars are .900 fine (90%) silver. Sterling silver silver is .925. "Pure" would be the .999 fine. I used to deal a fair bit in bullion and collectible coins. I seldom saw .999 silver in less than a full ounce apart from the occasional piece that was embeded in jewelry - meaning held into a ring or pendant by prongs or a bezel.