Gold Nugget (mango)
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A gold nugget is a naturally occurring piece of
native Native may refer to: People * '' Jus sanguinis'', nationality by blood * '' Jus soli'', nationality by location of birth * Indigenous peoples, peoples with a set of specific rights based on their historical ties to a particular territory ** Nat ...
gold Gold is a chemical element; it has chemical symbol Au (from Latin ) and atomic number 79. In its pure form, it is a brightness, bright, slightly orange-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal ...
.
Watercourse A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a strea ...
s often concentrate nuggets and finer gold in placers. Nuggets are recovered by
placer mining Placer mining () is the mining of stream bed deposits for minerals. This may be done by open-pit mining or by various surface excavating equipment or tunneling equipment. Placer mining is frequently used for precious metal deposits (particularly ...
, but they are also found in residual deposits where the gold-bearing
veins Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and fetal c ...
or
lode In geology, a lode is a deposit of metalliferous ore that fills or is embedded in a fracture (or crack) in a rock formation or a vein of ore that is deposited or embedded between layers of rock. The current meaning (ore vein) dates from th ...
s are weathered. Nuggets are also found in the
tailings In mining, tailings or tails are the materials left over after the process of separating the valuable fraction from the uneconomic fraction (gangue) of an ore. Tailings are different from overburden, which is the waste rock or other material ...
piles of previous mining operations, especially those left by
gold mining Gold mining is the extraction of gold by mining. Historically, mining gold from Alluvium, alluvial deposits used manual separation processes, such as gold panning. The expansion of gold mining to ores that are not on the surface has led to mor ...
dredges.


Formation

Nuggets are gold fragments weathered out of an original
lode In geology, a lode is a deposit of metalliferous ore that fills or is embedded in a fracture (or crack) in a rock formation or a vein of ore that is deposited or embedded between layers of rock. The current meaning (ore vein) dates from th ...
. 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 A supergene is a chromosomal region encompassing multiple neighboring genes that are inherited together because of close genetic linkage, i.e. much less recombination than would normally be expected. This mode of inheritance can be due to genomic ...
formation via ''in-situ'' precipitation,
cold welding Cold welding or contact welding is a solid-state welding process in which joining takes place without fusion or heating at the interface of the two parts to be welded. Unlike in fusion welding, no liquid or molten phase is present in the join ...
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 In ore deposit geology, hypogene processes occur deep below the Earth's surface, and tend to form deposits of primary minerals, as opposed to supergene processes that occur at or near the surface, and tend to form secondary minerals. At great d ...
origin). Other precious metals such as
platinum Platinum is a chemical element; it has Symbol (chemistry), symbol Pt and atomic number 78. It is a density, dense, malleable, ductility, ductile, highly unreactive, precious metal, precious, silverish-white transition metal. Its name origina ...
form nuggets in the same way. A later study of native gold from
Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...
, based on lead isotopes indicates that a significant part of the mass in alluvial gold nuggets in this area formed within the placer environment.


Composition

Nuggets are usually 20K to 22K purity (83% to 92% by
mass Mass is an Intrinsic and extrinsic properties, intrinsic property of a physical body, body. It was traditionally believed to be related to the physical quantity, quantity of matter in a body, until the discovery of the atom and particle physi ...
). Gold nuggets in
Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
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 The fineness of a precious metal object (coin, bar, jewelry, etc.) represents the weight of ''fine metal'' therein, in proportion to the total weight which includes alloying base metals and any impurities. Alloy metals are added to increase hard ...
, for example "865 fine" means the nugget is 865 parts per thousand in gold by mass. The common impurities are
silver Silver is a chemical element; it has Symbol (chemistry), symbol Ag () and atomic number 47. A soft, whitish-gray, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. ...
and
copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...
. Nuggets high in silver content constitute the alloy
electrum Electrum is a naturally occurring alloy of gold and silver, with trace amounts of copper and other metals. Its color ranges from pale to bright yellow, depending on the proportions of gold and silver. It has been produced artificially and is ...
. The chemical composition of supergene gold nuggets can reveal the characteristics of the primary ore.


Largest nuggets

Two gold nuggets are claimed as the largest in the world: the
Welcome Stranger Welcome Stranger is the name of the largest alluvial gold nugget ever discovered. It was unearthed by Cornwall, Cornish miners John Deason and Richard Oates on 5February 1869 in Moliagul, 9 miles north-west of Dunolly, Victoria, Dunolly in Vi ...
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 Moliagul is a locality in the Shire of Central Goldfields and Shire of Loddon, Victoria, Australia, located northwest of Melbourne and west of Bendigo. The area is notable for the discovery of a number of gold nuggets. These finds include the ...
, Victoria, Australia in 1869 by John Deason and Richard Oates. It weighed gross, over and returned over net. The Welcome Stranger is sometimes confused with the similarly named
Welcome Nugget The Welcome Nugget was a large gold nugget, weighing 2,217 troy ounces 16 pennyweight. (68.98 kg), that was discovered by a group of twenty-two Cornish miners at the Red Hill Mining Company site at Bakery Hill (near the present intersec ...
, which was found in June 1858 at Bakery Hill, Ballarat, Australia by the Red Hill Mining Company. The Welcome weighed . It was melted down in London in November 1859. The Canaã nugget, also known as the ''Pepita Canaa'', was found on September 13, 1983, by miners at the
Serra Pelada Serra Pelada (English: "Naked Mountain Range") is a Brazilian village, district of the municipality of Curionópolis, in the southeast of Pará. Serra Pelada was a large gold mine in Brazil, south of the mouth of the Amazon River. The mine wa ...
Mine in the State of Para, Brazil. Weighing gross, and containing of gold, it is among the largest gold nuggets ever found, 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 that broke during excavations. The
Canaã Canaã (Portuguese for "Canaan") is a municipality in the state of Minas Gerais in Brazil. The population is 4,548 (2020 est.) in an area of 175 km2. See also * List of municipalities in Minas Gerais This is a list of the municipalities in the St ...
nugget is displayed at the Banco Central Museum in Brazil along with the second and third largest nuggets remaining in existence, weighing respectively and , which were also found at the Serra Pelada region. The largest gold nugget found using a
metal detector A metal detector is an instrument that detects the nearby presence of metal. Metal detectors are useful for finding metal objects on the surface, underground, and under water. A metal detector consists of a control box, an adjustable shaft, and ...
is the
Hand of Faith The Hand of Faith is a gold nugget of fine-quality that was found by Kevin Hillier using a metal detector near Kingower, Victoria, Australia on 26 September 1980. Weighing 875 troy ounces (ozt; 27.21 kg, or 72 troy pounds and 11 troy ounce ...
, weighing , found in Kingower, Victoria, Australia in 1980. Historic large specimens include the
crystalline A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macrosc ...
" Fricot Nugget", weighing – the largest one found during the
California Gold Rush The California gold rush (1848–1855) began on January 24, 1848, when gold was found by James W. Marshall at Sutter's Mill in Coloma, California. The news of gold brought approximately 300,000 people to California from the rest of the U ...
. It is on display at the California State Mining and Mineral Museum. The largest gold nugget ever found in California weighed . It was found in August 1869 in
Sierra Buttes Sierra Buttes is an mountain summit located in the Sierra Nevada mountain range in Sierra County, California, United States. It is the third-highest point in Sierra County following the north ridge of Mount Lola and Peak 8740. Sierra Buttes ...
by five partners – W.A. Farish, A. Wood, J. Winstead, F.N.L. Clevering and Harry Warner. The Victoria, Australia gold rush of the early 1850s produced a number of large nuggets. They include the
Welcome Nugget The Welcome Nugget was a large gold nugget, weighing 2,217 troy ounces 16 pennyweight. (68.98 kg), that was discovered by a group of twenty-two Cornish miners at the Red Hill Mining Company site at Bakery Hill (near the present intersec ...
which weighed which is considered to be the second largest gold nugget ever found. Another find, the Lady Hotham, which weighed , 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). 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 , , and were also found in Canadian Gully at a depth of . Another nugget, the Heron, was found in 1855 in Golden Gully in the Mount Alexander goldfield. It weighed 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. On 16 January 2013, a large gold nugget was found near the city of
Ballarat Ballarat ( ) () is a city in the Central Highlands of Victoria, Australia. At the 2021 census, Ballarat had a population of 111,973, making it the third-largest urban inland city in Australia and the third-largest city in Victoria. Within mo ...
in Victoria, Australia by an amateur gold prospector. The Y-shaped nugget weighed slightly more than , measured around 22 cm high by 15 cm wide, and has a market value slightly below 300,000
Australian dollar The Australian dollar (currency sign, sign: $; ISO 4217, code: AUD; also abbreviated A$ or sometimes AU$ to distinguish it from other dollar, dollar-denominated currencies; and also referred to as the dollar or Aussie dollar) is the official ...
s, 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 Victoria most commonly refers to: * Queen Victoria (1819–1901), Queen of the United Kingdom and Empress of India * Victoria (state), a state of Australia * Victoria, British Columbia, Canada, a provincial capital * Victoria, Seychelles, the capi ...
's goldfields were exhausted in the 19th century.Sky News, Gold Find: Novice Prospector Earns Big Bucks, 17 January 2013
/ref>


See also

*
Gold mining Gold mining is the extraction of gold by mining. Historically, mining gold from Alluvium, alluvial deposits used manual separation processes, such as gold panning. The expansion of gold mining to ores that are not on the surface has led to mor ...
*
Gold prospecting Gold prospecting is the act of searching for new gold deposits. Methods used vary with the type of deposit sought and the resources of the prospector. Although traditionally a commercial activity, in some developed countries Placer mining, plac ...
*
Gold rush A gold rush or gold fever is a discovery of gold—sometimes accompanied by other precious metals and rare-earth minerals—that brings an onrush of miners seeking their fortune. Major gold rushes took place in the 19th century in Australia, ...
* Beyers-Holtermann Specimen, the largest specimen of
native gold Gold is a chemical element; it has chemical symbol Au (from Latin ) and atomic number 79. In its pure form, it is a bright, slightly orange-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal, a group ...
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 The Latrobe nugget is one of the largest clusters of cubic gold crystals known in the world and is kept at the Natural History Museum in London. The nugget weighs 717 grams. It was found at Mount McIvor, Victoria, Australia. It was raised on 1 ...
* Nugget (coin) *
Rocker box A rocker box (also known as a cradle or a big box) is a gold mining implement for separating alluvial placer gold from sand and gravel which was used in placer mining in the 19th century. It consists of a high-sided box, which is open on one ...


References

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