Editing Troy weight (section)

==History==
The origin of the troy weight system is unknown. Although the name probably comes from the [[Champagne fairs]] at [[Troyes]], in northeastern France.<ref>{{cite book |last=Smith |first=Adam |url=https://books.google.com/books?id=PeJMAAAAIAAJ&pg=PA35 |title=An Inquiry Into the Nature and Causes of the Wealth of Nations |date=1809 |publisher=T. Hamilton |volume=1 |location=London |page=35 |quote=The French livre contained, in the time of Charlemagne, a pound, Troyes weight, of silver of a known finess. The fair of Troyes in Champaign was at that time frequented by all the nations of Europe, and the weights and measures of so famous a market were generally known and esteemed.}}</ref> English troy weights were nearly identical to the troy weight system of [[Bremen]]. (The Bremen troy ounce had a mass of 480.8 British Imperial grains.)<ref name="1977zupko" />

Many aspects of the troy weight system were indirectly derived from the [[Roman currency|Roman monetary system]]. Before they used coins, [[Ancient Rome|early Romans]] used bronze bars of varying weights as currency. An {{Lang|la|[[aes grave]]}} ("heavy bronze") weighed one [[Pound (mass)|pound]]. One twelfth of an {{lang|la|aes grave}} was called an {{lang|la|[[Ancient Roman units of measurement#Weight|uncia]]}}, or in English, an "ounce". Before the adoption of the metric system, many systems of troy weights were in use in various parts of Europe, among them Holland troy, Paris troy, etc.<ref name="Kelly"/> Their values varied from one another by up to several percentage points. Troy weights were first used in England in the 15th century and were made official for gold and silver in 1527.<ref name="HallockWade1906" /> The British Imperial system of weights and measures (also known as [[imperial units]]) was established in 1824, prior to which the troy weight system was a subset of pre-imperial [[English units]].

The troy ounce in modern use is essentially the same as the British Imperial troy ounce (1824–1971), adopted as an official weight standard for United States coinage by act of [[United States Congress|Congress]] on May 19, 1828.<ref>{{cite book
| last = Hallock, Wade
| title = Outlines of the evolution of weights and measures and the metric system
| url = https://archive.org/details/outlinesevoluti00wadegoog
| publisher=The Macmillan company
| year = 1906
| page = [https://archive.org/details/outlinesevoluti00wadegoog/page/n134 119]
}}</ref> The British Imperial troy ounce (known more commonly simply as the imperial troy ounce) was based on, and virtually identical with, the pre-1824 British troy ounce and the pre-1707 English troy ounce. (1824 was the year the British Imperial system of weights and measures was adopted; 1707 was the year of the [[Acts of Union 1707|Act of Union]] which created the [[Kingdom of Great Britain]].) Troy ounces have been used in England since the early 15th century, and the English troy ounce was officially adopted for coinage in 1527. Before that time, various sorts of troy ounces were in use on the continent.<ref name="1977zupko">{{cite book
| last = Zupko
| first = Ronald Edward
| author-link = Ronald Edward Zupko
| title = British Weights and Measures: A History from Antiquity to the Seventeenth Century
| publisher=University of Wisconsin Press
| year = 1977
| isbn = 978-0-299-07340-4
| pages = 28–9
}}</ref>

The troy ounce and grain were also part of the [[apothecaries' system]]. This was long used in medicine, but has been largely replaced by the [[metric system]] (milligrams).<ref name="dictionary.com">{{cite web | title=Troy Ounce | url=http://dictionary.reference.com/browse/troy%20ounce | work=WordNet 3.0, Dictionary.com | publisher=Princeton University | access-date=2008-01-10 | url-status=live | archive-url=https://web.archive.org/web/20080226004653/http://dictionary.reference.com/browse/troy%20ounce | archive-date=2008-02-26 }}</ref> The only troy weight in widespread use is the British Imperial troy ounce and its American counterpart. Both are based on a grain of 0.06479891&nbsp;gram (exact, by definition), with 480 grains to a troy ounce (compared with {{frac|437|1|2}} grains for an ounce avoirdupois). The British Empire abolished the 12-ounce troy pound in the 19th century. It has been retained, though rarely used, in the American system. Larger amounts of precious metals are conventionally counted in hundreds or thousands of troy ounces, or in kilograms.

Troy ounces have been and are still often used in precious metal markets in countries that otherwise use [[International System of Units]] (SI).<ref>{{cite web|url=http://www.boerse-frankfurt.de/de/rohstoffe/xetra+gold|title=Börse Frankfurt: Aktien, Kurse, Charts und Nachrichten|website=www.boerse-frankfurt.de|access-date=28 April 2018|url-status=live|archive-url=https://web.archive.org/web/20151101044103/http://www.boerse-frankfurt.de/de/rohstoffe/xetra+gold|archive-date=1 November 2015}}</ref><ref>{{cite web|url=http://www.perthmint.com.au/education_uom.aspx|title=Units of Measure - The Perth Mint|url-status=live|archive-url=https://web.archive.org/web/20150924071802/http://www.perthmint.com.au/education_uom.aspx |archive-date=2015-09-24}}</ref> However, the [[People's Bank of China]]{{snd}} which had been using troy measurements in minting [[Chinese Gold Panda#Revised weights|Gold Pandas]] since 1982{{snd}} from 2016 specifies Chinese bullion coins in an integer numbers of grams.<ref>{{cite web |url=http://www.numismaster.com/ta/numis/Article.jsp?ArticleId=28158 |title=Do grams or ounces win? |url-status=dead |archive-url=https://web.archive.org/web/20160506234211/http://www.numismaster.com/ta/numis/Article.jsp?ArticleId=28158|archive-date=2016-05-06 |first= Pat |last=Heller |date=December 21, 2015 |website=Numismaster.com}}</ref>