Gold nugget

File:GoldNugget.jpg, California, on display at the National Museum of Natural History in Washington, D.C.]]

Nuggets are gold fragments weathered out of an original lode.{{Cite journal |last=Butt |first= C. R. M. |author2=Hough, R. M. |author3=Reddy, S. M. |author4= Verrall, M. |title=Origin and weathering of gold nuggets |journal=Geochimica et Cosmochimica Acta |volume=70 |issue=18 |pages=A78 |date=August–September 2006 |url=http://crcleme.org.au/Pubs/Articles%20and%20papers/Goldsmidt_butt01004.pdf |doi=10.1016/j.gca.2006.06.259 |bibcode= 2006GeCAS..70Q..78B |access-date=August 18, 2012}} They often show signs of abrasive polishing by stream action, and sometimes still contain inclusions of quartz or other lode matrix material. A 2007 study on Australian nuggets ruled out speculative theories of supergene formation via in-situ precipitation, cold welding of smaller particles, or bacterial concentration, since crystal structures of all of the nuggets examined proved they were originally formed at high temperature deep underground (i.e., they were of hypogene origin).{{citation |year=2007 |title=Gold nuggets reveal their inner secrets |publisher=Phys.Org |url=http://phys.org/news111763640.html |access-date=August 11, 2012}}{{Cite journal |last=Hough |first=R. M. |author2=Butt, C. R. M. |author3=Reddy, S. M. |author4= Verrall, M. |title=Gold nuggets: supergene or hypogene? |journal=Australian Journal of Earth Sciences |volume=54 |issue=7 |pages=959–964 |year=2007 |doi=10.1080/08120090701488289 |bibcode=2007AuJES..54..959H }}

Other precious metals such as platinum form nuggets in the same way. A later study of native gold from Arizona, based on lead isotopes indicates that a significant part of the mass in alluvial gold nuggets in this area formed within the placer environment.{{cite journal |last=Kamenov|first=G. D. |author2=Melchiorre, E. B. |author3=Ricker, F. N. |author4=DeWitt, E. |title=Insights from Pb Isotopes for Native Gold Formation During Hypogene and Supergene Processes at Rich Hill, Arizona |journal=Economic Geology |volume=108|issue=7 |pages=1577–1589|year=2013 |url=http://econgeol.geoscienceworld.org/content/108/7/1577.abstract |doi=10.2113/econgeo.108.7.1577 |bibcode=2013EcGeo.108.1577K |access-date=August 9, 2014|url-access=subscription }}

Nuggets are usually 20K to 22K purity (83% to 92% by mass). Gold nuggets in Australia often are 23K or slightly higher, while Alaskan nuggets are usually at the lower end of the spectrum. Purity can be roughly assessed by the nugget color, the richer and deeper the orange-yellow the higher the gold content. Nuggets are also referred to by their fineness, for example "865 fine" means the nugget is 865 parts per thousand in gold by mass. The common impurities are silver and copper. Nuggets high in silver content constitute the alloy electrum.{{cite book|last=McLaren|first=J. Malcolm|title=Gold: Its Geological Occurrence and Geographical Distribution}} The chemical composition of supergene gold nuggets can reveal the characteristics of the primary ore.Horbe, A. M. C., Martins-Ferreira, M. A. C., & Lima, R. S. (2019). Supergene gold characterization by geochemistry, grain morphology and Au-Ag-Cu-Te classification. Journal of South American Earth Sciences, 95, 102315.

File:Gold-270415.jpg of central Alaska. 6.6 x 2.0 x 1.1 cm. Weight: 77 grams]]

{{Main|List of gold nuggets by size}}

Two gold nuggets are claimed as the largest in the world: the Welcome Stranger and the Canaã nugget, the latter being the largest surviving natural nugget. Considered by most authorities to be the biggest gold nugget ever found, the Welcome Stranger was found at Moliagul, Victoria, Australia in 1869 by John Deason and Richard Oates. It weighed gross, over {{convert|2520|ozt|kg lb|lk=in}} and returned over {{convert|2284|ozt|kg lb}} net.{{cite book|last=Dunn|first=E.J.|title=Memoirs of the Geological Survey of Victoria|year=1912}} The Welcome Stranger is sometimes confused with the similarly named Welcome Nugget, which was found in June 1858 at Bakery Hill, Ballarat, Australia by the Red Hill Mining Company. The Welcome weighed {{convert|2218|ozt|kg lb|lk=in}}. It was melted down in London in November 1859.{{cite web |url=http://www.sbs.com.au/gold/story.php?storyid=113#2453 |title=Famous Australian Nuggets |location=Australia |access-date=February 16, 2013}}

The Canaã nugget, also known as the Pepita Canaa, was found on September 13, 1983, by miners at the Serra Pelada Mine in the State of Para, Brazil. Weighing {{convert|1955|ozt|kg lb}} gross, and containing {{convert|1682.5|ozt|kg lb}} of gold,{{cite web|author1=Marcello M. Veiga|author2=Stephen M. Metcalf|author3=Randy F. Baker|author4=Bern Klein|author5=Gillian Davis|author6=Andrew Bamber|author7=Shefa Siegel|title=GMP – Manual for Training Artisanal and Small-Scale Gold Miners|url=http://projects.inweh.unu.edu/inweh/display.php?ID=2451|website=Global Mercury Project|publisher=United Nations Industrial Development Organization (UNIDO)|access-date=25 October 2014|archive-date=4 March 2016|archive-url=https://web.archive.org/web/20160304044423/http://projects.inweh.unu.edu/inweh/display.php?ID=2451|url-status=dead}}{{cite web|title=Maior pepita de ouro exposta do mundo está em Brasília|url=http://www.brasil.gov.br/cultura/2017/07/maior-pepita-de-ouro-exposta-do-mundo-esta-em-brasilia|website=Governo do Brasil|access-date=5 November 2017|language=pt-BR}} it is among the largest gold nuggets ever found,{{cite web |url=http://arizona-gold-fever.blogspot.ca/2011/03/top-5-largest-gold-nuggets-in-world.html |title=Top 5 largest gold nuggets in the world |date=29 March 2011 |location=Arizona |access-date=January 17, 2013}}{{cite web|url=http://scienceline.ucsb.edu/getkey.php?key=3945 |title=UCSB Science Line |access-date=June 22, 2013}} and is, today, the largest in existence. The main controversy regarding this nugget is that the excavation reports suggest that the existing nugget was originally part of a nugget weighing {{convert|5291.09|ozt|kg lb|lk=in|sigfig=3}} that broke during excavations.{{cite book|last=Branco|first=P.M.|title=Dicionário de Mineralogia e Gemologia São Paulo, Oficina de Textos, 608 p. il.|year=2008}} The Canaã nugget is displayed at the Banco Central Museum in Brazil along with the second and third largest nuggets remaining in existence, weighing respectively {{convert|1506.2|ozt|kg lb|lk=in}} and {{convert|1393.3|ozt|kg lb|lk=in}}, which were also found at the Serra Pelada region.{{cite book|title=Minerals & Precious Stones of Brazil|author=Carlos Cornejo & Andrea Bartorelli|year=2010}}

The largest gold nugget found using a metal detector is the Hand of Faith, weighing {{convert|875|ozt|kg lb|lk=in}}, found in Kingower, Victoria, Australia in 1980.

Historic large specimens include the crystalline "Fricot Nugget", weighing {{convert|201|ozt|kg lb|lk=in}} – the largest one found during the California Gold Rush. It is on display at the California State Mining and Mineral Museum.

The largest gold nugget ever found in California weighed {{convert|1593|ozt|kg lb|lk=in}}. It was found in August 1869 in Sierra Buttes by five partners – W.A. Farish, A. Wood, J. Winstead, F.N.L. Clevering and Harry Warner.{{cite book|last=Hurley|first=Thomas Jefferson|title=Famous Gold Nuggets of the World|url=https://archive.org/details/famousgoldnugget00hurlrich|year=1900|publisher=New York?}}

The Victoria, Australia gold rush of the early 1850s produced a number of large nuggets. They include the Welcome Nugget which weighed {{convert|68.98|kg|lb|lk=in}} which is considered to be the second largest gold nugget ever found.{{cite web | url=http://museumvictoria.com.au/discoverycentre/infosheets/gold-nuggets/ | archive-url=https://web.archive.org/web/20080317010807/http://museumvictoria.com.au/DiscoveryCentre/Infosheets/Gold-Nuggets/ | url-status=dead | archive-date=March 17, 2008 | title=Gold Nuggets – Museum Victoria | access-date=2013-06-23}}{{cite web|url=http://www.discoverychannel.com.au/image-galleries/gold-nuggets |title=World's Biggest Gold Nuggets |publisher=Discovery Channel Australia |access-date=2013-06-23 |url-status=dead |archive-url=https://web.archive.org/web/20130430075900/http://www.discoverychannel.com.au/image-galleries/gold-nuggets |archive-date=2013-04-30 }}{{cite web | url=http://www.thecourier.com.au/story/557619/welcome-nugget-153-years-since-discovery/ | title=Welcome Nugget: 153 years since discovery | publisher=Fairfax Regional Media | work=The Courier | date=9 June 2011 | access-date=2013-06-23}} Another find, the Lady Hotham, which weighed {{convert|98.5|lb|kg|lk=in}}, was found by a group of nine miners on September 8, 1854, in Canadian Gully, Ballarat at a depth of 135 feet (41.2 m).{{cite news |url=http://nla.gov.au/nla.news-article91859458 |title=BALLARAT. |newspaper=Geelong Advertiser and Intelligencer (Vic. : 1851 – 1856) |location=Vic. |date=12 September 1854 |access-date=28 April 2013 |page=4 Edition: DAILY |publisher=National Library of Australia}} The Lady Hotham was named after the wife of the Governor, Sir Charles Hotham who happened to be visiting the area when the nugget was found. Eighteen months earlier, in January and early February 1853, three other large nuggets weighing {{convert|134|lb|kg|lk=in}}, {{convert|93.125|lb|kg|lk=in}}, and {{convert|83.5|lb|kg|lk=in}} were also found in Canadian Gully at a depth of {{convert|55|to|60|ft|m|lk=in}}.{{cite news |url=http://nla.gov.au/nla.news-article94362227 |title=MORE LARGE MASSES OF GOLD. |newspaper=Geelong Advertiser and Intelligencer (Vic. : 1851 – 1856) |location=Vic. |date=8 February 1853 |access-date=28 April 2013 |page=1 Edition: DAILY., Supplement: SUPPLEMENT TO THE GEELONG ADVERTISER AND INTELLIGENCER |publisher=National Library of Australia}} Another nugget, the Heron, was found in 1855 in Golden Gully in the Mount Alexander goldfield. It weighed {{convert|1008|ozt|kg lb|lk=in}} and was found by a group of inexperienced miners who had received a supposedly empty claim. The miners found the nugget on their second day of digging; the nugget was named after one of the gold commissioners, a Mr. Heron.{{cite web |url=http://www.goldoz.com.au/historical_finds_and_discoveries.0.html |title=Historical Finds and Discoveries |location=Australia |access-date=February 17, 2013 |url-status=dead |archive-url=https://web.archive.org/web/20100222233205/http://goldoz.com.au/historical_finds_and_discoveries.0.html |archive-date=February 22, 2010 }}

On 16 January 2013, a large gold nugget was found near the city of Ballarat in Victoria, Australia by an amateur gold prospector. The Y-shaped nugget weighed slightly more than {{convert|5|kg|lb|lk=in}}, measured around 22 cm high by 15 cm wide, and has a market value slightly below 300,000 Australian dollars, though opinions have been expressed that it could be sold for much more due to its rarity. The discovery has cast doubt on the common rumour that Victoria's goldfields were exhausted in the 19^th century.[http://www.thecourier.com.au/story/1242592/gold-nugget-found-near-ballarat/ Gold nugget found near Ballarat][http://news.sky.com/story/1039397/gold-find-novice-prospector-earns-big-bucks Sky News, Gold Find: Novice Prospector Earns Big Bucks, 17 January 2013]

• Gold mining
• Gold prospecting
• Gold rush
• Beyers-Holtermann Specimen, the largest specimen of native gold ever found. Essentially reef gold, thus with quartz and, therefore, not a nugget (which is typically alluvial gold). It contained approx. 3,000 troy oz (93.3 kg) of gold, thus 25% more gold than the largest nugget.
• Latrobe nugget
• Nugget (coin)
• Rocker box

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Nugget