Ounce (Troy), mass
In troy weight, there are 12 ounces in a pound, and a troy pound is 5760 grains (about 373.24 g), rather than 7000 (about 453.59 g). Note: at roughly 31.104 g, the troy ounce is about 10 per cent more than the more-common avoirdupois ounce. These troy ounces are now used only when weighing precious metals like gold, platinum and silver. One ounce of gold is always 31.1 g. "Maria Theresa Ounce" was once introduced in Ethiopia and some European countries, which was equal to 31.1025 g.