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'[[File:1 oz of fine gold.jpg|thumb|Troy ounce is a traditional unit of [[gold]] weight.]] [[Image:American Platinum Eagle 2008 Proof Rev.jpg|thumb|1 troy ounce (1.097 avoirdupois ounces, 31.1 g) coin example ([[American Platinum Eagle|Platinum Eagle]])]] [[File:Ingots of Ge, Fe, Al, Re, Os, one troy ounce each (2).jpg|thumb|{{convert|1|ozt|spell=In}} samples of [[germanium]], [[iron]], [[aluminium]], [[rhenium]] and [[osmium]]]] [[File:1000oz.silver.bullion.bar.underneath.jpg|thumb|A [[Good Delivery]] silver bar weighing {{convert|1000|ozt|lb kg}}]] '''Troy weight''' is a system of [[Physical unit|unit]]s of [[mass]] that originated in 15th-century England<ref name="HallockWade1906">{{cite book|last1=Hallock|first1=William|authorlink1=William Hallock|last2=Wade|first2=Herbert Treadwell|title=Outlines of the evolution of weights and measures and the metric system|url=https://books.google.com/books?id=kJ0gAAAAMAAJ&pg=PA34|accessdate=14 August 2012|year=1906|publisher=The Macmillan company|location=London|page=34|url-status=live|archiveurl=https://web.archive.org/web/20140105072502/http://books.google.com/books?id=kJ0gAAAAMAAJ&pg=PA34|archivedate=5 January 2014}}</ref>, and is primarily used today in the [[precious metal]]s industry. Its units are the [[Grain (unit)|grain]], [[pennyweight]] (24 grains), troy ounce (20 pennyweights), and troy pound (12 troy ounces). The grain is the same grain used in the more common [[Avoirdupois | avoirdupois system]]. By contrast, the troy ounce is heavier than the avoirdupois ounce, while the troy pound is lighter than the avoirdupois pound. ==Etymology== Troy weight probably takes its name from the French market town of [[Troyes]] in France where English merchants traded at least as early as the early 9th century.<ref name="OED3troy2">{{cite book|title=[[Oxford English Dictionary]]|chapter-url=http://www.oed.com/view/Entry/206831|date=June 2012|publisher=Oxford University Press|location=Oxford, England|chapter=troy, n.²|quote=The received opinion is that it took its name from a weight used at the fair of Troyes in France}}</ref><ref>{{cite book|last=Partridge|first=Eric|authorlink=Eric Partridge|title=Origins: A Short Etymological Dictionary of Modern English|url=https://archive.org/details/originsshortetym0000part_z7h8|url-access=registration|year=1958|publisher=Routledge and Kegan Paul|location=London|page=3566|chapter=Trojan|oclc=250202885|quote=…the great fairs established for all Europe the weight-standard ''Troyes'', whence…''Troy''…}}</ref> The name "troy" is first attested in 1390, describing the weight of a platter, in an account of the travels in Europe of the [[Henry IV of England#Relationship with Richard II|Earl of Derby]].<ref name="OED3troy2" /><ref>{{cite book|last=Smith|first=L. Toulmin|authorlink=Lucy Toulmin Smith|title=Expeditions to Prussia and the Holy Land Made by Henry Earl of Derby (afterwards King Henry IV.) in the Years 1390-1 and 1392-3|url=https://books.google.com/books?id=wvIIAAAAIAAJ&pg=PA100|accessdate=14 August 2012|year=1894|publisher=Camden Society|location=London|url-status=live|archiveurl=https://web.archive.org/web/20140703063211/http://books.google.com/books?id=wvIIAAAAIAAJ&pg=PA100|archivedate=3 July 2014}}</ref> Charles Moore Watson (1844–1916) proposes an alternative etymology: ''The Assize of Weights and Measures'' (also known as ''[[Weights and Measures Acts (UK)#Acts of Parliament|Tractatus de Ponderibus et Mensuris]]''), one of the [[statutes of uncertain date]] from the reign of either [[Henry III of England|Henry III]] or [[Edward I of England|Edward I]], thus before 1307, specifies "troni ponderacionem"—which the Public Record Commissioners translate as "troy weight". The word "troni" refers to markets. Watson finds the dialect word "troi", meaning a [[Weighing scale|balance]] in Wright's Dialect Dictionary. Troy weight referred to the tower system; the earliest reference to the modern troy weights is in 1414.<ref name="CMW1910">{{cite book|last=Watson|first=Charles Moore|title=British weights and measures as described in the laws of England from Anglo-Saxon times|url=https://archive.org/stream/britishweightsme00watsuoft/britishweightsme00watsuoft_djvu.txt|year=1910|publisher=John Murray|location=London|page=82|oclc=4566577|url-status=live|archiveurl=https://web.archive.org/web/20160401195759/http://archive.org/stream/britishweightsme00watsuoft/britishweightsme00watsuoft_djvu.txt|archivedate=2016-04-01}}</ref><ref>{{cite book|last=Wright|first=Joseph|authorlink=Joseph Wright (linguist)|title=The English dialect dictionary|volume=6|year=1898|publisher=English Dialect Society|location=Oxford|page=250|oclc=63381077}}</ref> ==History== Many aspects of the troy weight system were indirectly derived from the [[Roman currency|Roman monetary system]]. The [[Ancient Rome|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>Patrick Kelly, LL.D. - [https://books.google.com/books?id=iqtLAAAAYAAJ&pg=PA20&dq=%22The+Universal+Cambist%22+%22when+silver+is+sold+in+bars%22&hl=en&ei=L5q-TojYF6OziQK37cmoCQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CEkQ6AEwAA#v=onepage&q&f=false The Universal Cambist and Commercial Instructor, Vol. 1] {{webarchive|url=https://web.archive.org/web/20170327193151/https://books.google.com/books?id=iqtLAAAAYAAJ&pg=PA20&dq=%22The+Universal+Cambist%22+%22when+silver+is+sold+in+bars%22&hl=en&ei=L5q-TojYF6OziQK37cmoCQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CEkQ6AEwAA |date=2017-03-27 }} p. 20 (1811)</ref> 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">{{cite book|last1=Hallock|first1=William|authorlink1=William Hallock|last2=Wade|first2=Herbert Treadwell|title=Outlines of the evolution of weights and measures and the metric system|url=https://books.google.com/books?id=kJ0gAAAAMAAJ&pg=PA34|accessdate=14 August 2012|year=1906|publisher=The Macmillan company|location=London|page=34|url-status=live|archiveurl=https://web.archive.org/web/20140105072502/http://books.google.com/books?id=kJ0gAAAAMAAJ&pg=PA34|archivedate=5 January 2014}}</ref> 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 use today 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 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 = 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 about 1400 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 | authorlink = 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 now 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 | accessdate=2008-01-10 | url-status=live | archiveurl=https://web.archive.org/web/20080226004653/http://dictionary.reference.com/browse/troy%20ounce | archivedate=2008-02-26 }}</ref> The only troy weight in widespread use today is the British Imperial troy ounce and its American counterpart. Both are currently 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, though it has been retained (although rarely used) in the American system. ===Origin=== 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 |title = An Inquiry Into the Nature and Causes of the Wealth of Nations, Volume 1 |publisher = T. Hamilton |volume = 1 |date = 1809 |location = London |pages = 35 |language = English |url = https://books.google.com/books?id=PeJMAAAAIAAJ&pg=PA35 |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. |url-status = live |archiveurl = https://web.archive.org/web/20170222103806/https://books.google.com/books?id=PeJMAAAAIAAJ&pg=PA35 |archivedate = 2017-02-22 }}</ref> the units themselves may be of more northern origin.{{Citation needed|date=September 2016}} 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"/> An alternative suggestion is that the weights come from the Muslim domains by way of the Gold [[Dirham|Dirhem]] (47.966 British Imperial grains), in the manner that [[King Offa]]'s weights were derived from the silver Dirhem (about 45.0 British grains). According to Watson, troy relates to a dialect word '''troi''' (balance). Then troy weight is a style of weighing, like [[auncel]] or [[bismar]] weights, or other kindred methods. The troy weight then refers to weighing of small precious or potent goods, such as [[bullion]] and medicines.<ref name="CMW1910"/> === Use in other countries === Troy ounces 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|accessdate=28 April 2018|url-status=live|archiveurl=https://web.archive.org/web/20151101044103/http://www.boerse-frankfurt.de/de/rohstoffe/xetra+gold|archivedate=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|archiveurl=https://web.archive.org/web/20150924071802/http://www.perthmint.com.au/education_uom.aspx|archivedate=2015-09-24}}</ref> except in [[East Asia]].<ref>{{cite web|url=http://www.numismaster.com/ta/numis/Article.jsp?ArticleId=28158|title=Do grams or ounces win?|url-status=live|archiveurl=https://web.archive.org/web/20160506234211/http://www.numismaster.com/ta/numis/Article.jsp?ArticleId=28158|archivedate=2016-05-06}}</ref> The [[People's Bank of China]], in particular, which has never historically used troy measurements, has begun issuing [[Chinese Gold Panda#The 2016 Panda gold coin|Gold Pandas]] minted according to [[International System of Units|SI weights]]. ==Units of measurement== [[File:comparison of pounds.svg|thumb|400px|Chart comparing the mass (in grams) of tower, Troy, merchant, avoirdupois and London pounds. Each colored block represents one ounce (gold=Troy, blue= avoirdupois, purple=tower)]] === Troy pound === The troy pound is 5760&nbsp;grains (≈ 373.24&nbsp;g, 12&nbsp;oz&nbsp;t), while an [[avoirdupois]] pound is approximately 21.53% heavier at 7000&nbsp;grains (≈ 453.59&nbsp;g). === Troy ounce (oz&nbsp;t) === Because of the [[International yard and pound]] agreement, one troy ounce (oz&nbsp;t) equals exactly {{nowrap|31.103 476 8}} grams. It also equals {{val|1.09714286}} avoirdupois ounces, or exactly {{frac|192|175}}, about 10% larger. The international yard and pound agreement did not define any troy weights. Rather, it defined the avoirdupois pound in metric terms, from which we can derive an exact value for the troy ounce. Specifically, it defined one pound as {{val|0.45359237|u=kg}}. We can derive an exact value for the troy ounce as follows: :1 lb = {{val|0.45359237|u=kg}} = {{val|453.59237|u=grams}} An avoirdupois pound also equals 7000 grains (the international yard and pound agreement did not change the grain values of non-metric units). :1 lb = 7000 grains :7000 grains = {{val|453.59237|u=grams}} :1 grain = {{sfrac|{{val|453.59237|u=grams}}|7000 grains}} = {{val|0.06479891|u=g/gr}} :1 troy ounce = 480 grains × {{val|0.06479891|u=g/gr}} = {{val|31.1034768|u=grams}} === Pennyweight (dwt) === {{main|Pennyweight}} The pennyweight symbol is ''dwt''. There are 24 grains in 1 dwt, and 20 dwt in one troy ounce. Because there were 12 troy ounces in the old troy pound, there would have been 240 pennyweights to the pound—the basis of the fact that the [[Anglo-Saxon pound|old British pound sterling]] of currency contained 240 pence. (However, prior to 1526, English [[pound sterling]] was based on the [[tower pound]], which is {{frac|15|16}} of a troy pound.) The ''d'' in ''dwt'' stands for ''[[denarius]]'', the ancient Roman coin that equates loosely to a penny. The symbol ''d'' for penny can be recognized in the notation for British pre-decimal pennies, in which pounds, shillings, and pence were indicated using the symbols ''£'', ''s'', and ''d'', respectively. For example, ''£6 11s 8d'' indicated six pounds, eleven shillings, and eight pence. === Troy grain === {{main|Grain (mass)}} === Mint weights === Mint weights, also known as ''moneyers' weights'' were legalised by Act of Parliament dated 17 July 1649 entitled ''An Act touching the monies and coins of England''. A grain is 20 mites, a mite is 24 droits, a droit is 20 perits, a perit is 24 blanks.<ref name="Britain)1891">{{cite book|author=Philological Society (Great Britain)|title=A new English dictionary on historical principles: founded mainly on the materials collected by the Philological Society|url=https://books.google.com/books?id=k2xXAAAAYAAJ&pg=PA675|accessdate=21 April 2012|year=1891|publisher=Clarendon Press|page=675|url-status=live|archiveurl=https://web.archive.org/web/20140627192804/http://books.google.com/books?id=k2xXAAAAYAAJ&pg=PA675|archivedate=27 June 2014}}</ref><ref name="Miege">{{cite book|author=Miege, Guy|title=The Present State of Great Britain and Ireland|url=https://books.google.com/books?id=BDs2AAAAMAAJ&pg=PA307&lpg=PA307#v=onepage&q&f=false|accessdate=6 June 2017|year=1738|publisher=J. Brotherton, A. Bettesworth and C. Hitch, G. Strahan, W. Mears, R. Ware, E. Symon, and J. Clark|page=307|url-status=live|archiveurl=https://web.archive.org/web/20180428213432/https://books.google.com/books?id=BDs2AAAAMAAJ&pg=PA307&lpg=PA307#v=onepage&q&f=false|archivedate=28 April 2018}}</ref> ==Scottish system== In Scotland, the [[Edinburgh Assay Office|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 [[Scottish units#Weight|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 7716 British Imperial grains, but after the union, rounded to 7680 BI grains. This divides to 16 ounces, each of 16 drops, each of 30 grains. The rounding makes the ounce and grain equal to the English standard. ==Dutch system== The Dutch troy system is based on a Mark, of 8 Ounces, the ounce of 20 Engels (pennyweight), the Engel of 32 As. The mark was rated as 3798 Grains, English troy, or 246.084 metric grams. The divisions are identical to the tower system.<ref name=Kelly>{{cite book|last=Kelly|first=Patric|title=Universal Cambist|year=1835|location=London}}</ref> ==Conversions== {| class="wikitable" ! Unit !! Grains !! Grams (exact) |- | Troy pound (12 troy ounces) || style="text-align:right;"| 5,760 || style="text-align:right;"| 373.24172&nbsp;16<span style="visibility:hidden;">0</span> |- | Troy ounce (20 pennyweights) || style="text-align:right;"| 480 || style="text-align:right;"| 31.10347&nbsp;68<span style="visibility:hidden;">0</span> |- | Pennyweight || style="text-align:right;"| 24 || style="text-align:right;"| 1.55517&nbsp;384 |- | Grain || style="text-align:right;"| 1 || style="text-align:right;"| 0.06479&nbsp;891 |} {{English pounds}} The troy system was used in the [[apothecaries' system]], but with different further subdivisions. ==Relationship to British coinage== King [[Offa]]'s [[currency]] reform replaced the [[sceat]] with the [[silver]] [[penny]]. This coin was derived from half of a silver [[dirhem]]. The weights were then derived by a count of coins, by a mix of [[Charlemagne]] and [[Roman Empire|Roman]] systems. A [[shilling]] was set to twelve [[pence]], an [[ounce]] to twenty pence, and a [[British pound|pound]] to twelve ounces or twenty shillings. The penny was quite a lot of money, so weight by coins was not a general practice. Later kings debased the coin, both in weight and fineness. The original pound divided was the [[tower pound]] of 5400 [[grain]]s, but a later pound of 5760 grains displaced it. Where once 240 pence made a tower pound (and 256 make a troy pound), by the time of the [[Weights and Measures Acts (UK)|United Kingdom Weights and Measures Act]] of 1824, a troy pound gives 792 silver pence, still minted as such as [[Maundy Money]]. [[Sterling silver|Sterling]] originally referred to the Norman silver penny of the late 11th century.{{citation needed|date=September 2016}} The coin was minted to a fineness of 11 oz, 2 dwt (in the pound), or 925 [[Millesimal fineness]]. ==See also== * [[Carat (unit)]] * [[Conversion of units]] * [[English units]] * [[Fluid ounce]] * [[Grain (unit)]] * [[Imperial units]] * [[Mark (weight)]] * [[Tola (unit)]] * [[United States customary units]] ==References== {{reflist}} {{systems of measurement}} [[Category:Units of mass]] [[Category:Precious metals]] [[Category:Systems of units]]'