System of measurement The same is true of quarts, gallons, etc. Six US gallons are a little less than five imperial gallons. The Avoirdupois system served as the general system of mass and weight. In addition to this there are the Troy and the Apothecaries' systems. Troy weight was customarily used for precious metals, black powder and gemstones. The troy ounce is the only unit of the system in current use; it is used for precious metals. Although the troy ounce is larger than its Avoirdupois equivalent, the pound is smaller. The obsolete troy pound was divided into 12 ounces, rather than the
Mithqal Mithqal Mithqāl () is a unit of mass equal to 4.5 grams which is mostly used for measuring precious metals, such as gold, and other commodities, like saffron. The name was also applied as an alternative term for the gold dinar, a coin that was used throughout much of the Islamic world from the 8th century onward and survived in parts of Africa until the 19th century. The name of Mozambique's currency since 1980, the "metical", is derived from "mithqāl". The word "mithqāl" (; “weight, unit of weight”) comes from the Arabic "thaqala" (), meaning “to weigh”. Other variants of