Troy ounce
From Wikipedia, the free encyclopedia
The troy ounce (ozt) is 480 grains, somewhat heavier than an avoirdupois ounce (437.5 grains).[1] A grain is 64.79891 mg; hence one troy ounce is 31.1034768 g, about 10 percent more than the avoirdupois ounce, which is 28.349523125 g. The troy ounce is traditionally used over the avoirdupois ounce in the pricing of precious metals, gold, platinum, and silver. The grain, which is identical in both the troy and avoirdupois systems, is used to measure arrow and arrowhead weights in archery and bullets and powder weights in ballistics. The grain is also common to the apothecaries' system and was long used in medicine, but has been largely replaced by milligrams.
The "troy ounce" is derived from the Roman monetary system. The Romans used bronze bars of varying weights as currency. An "Aes Grave" weighed in at 1 pound. 1/12th of an Aes Grave was called an uncia, in English "ounce". Later standardizations would change the ounce to 1/16th of a pound, but the 1/12th pound ounce is still used for measuring precious metals.
[edit] See also
[edit] References
- ^ "Troy Ounce". WordNet 3.0, Dictionary.com. Princeton University. http://dictionary.reference.com/browse/troy%20ounce. Retrieved on 2008-01-10.
