Troy weight A grain is 20 mites, a mite is 24 droits, a droit is 20 perits, a perit is 24 blanks. In Scotland, the Incorporation of Goldsmiths of the City of Edinburgh used a system in multiples of sixteen. ("See Assay-Master's Accounts, 1681–1702, on loan from the Incorporation to the National Archives of Scotland".) Thus, there were 16 drops to the troy ounce, 16 ounces to the troy pound, and 16 pounds to the troy stone. The Scots had several other ways of measuring precious metals and gems, but this was the common usage for gold and silver. The Pound was
Coinage metals well known in the Persian and Sassanids era. Most notably, in Susa and in Ctesiphon. However, there are many more, even for coins made from intrinsically precious metals. Precious metals are always used in bullion coins and some collectable coins. Coins not intended for circulation or for intrinsic value have also been made experimentally using an even larger variety of metals, since they function as fiat money. In general coins intended for circulation must have metal values considerably less than their face values, for reasons discussed below. Coins that are intended for circulation have some special requirements based on the