"Electrum Electrum is a naturally occurring alloy of gold and silver, with trace amounts of copper and other metals. It has also been produced artificially, and is often known as green gold. The ancient Greeks called it 'gold' or 'white gold', as opposed to 'refined gold'. Its colour ranges from pale to bright yellow, depending on the proportions of gold and silver. The gold content of naturally occurring electrum in modern Western Anatolia ranges from 70% to 90%, in contrast to the 45–55% of gold in electrum used in ancient Lydian coinage of the same geographical area. This suggests that"
"The metal occurs naturally in its pure, free form (native silver), as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite. Most silver is produced as a byproduct of copper, gold, lead, and zinc refining. Silver has long been valued as a precious metal, and it is used to make ornaments, jewelry, high-value tableware, utensils (hence the term ""silverware""), and currency coins. Today, silver metal is also used in electrical contacts and conductors, in mirrors and in catalysis of chemical reactions. Its compounds are used in photographic film, and dilute silver nitrate solutions and"
"Billon (alloy) Billon is an alloy of a precious metal (most commonly silver, but also mercury) with a majority base metal content (such as copper). It is used chiefly for making coins, medals, and token coins. The word comes from the French ""bille"", which means ""log"". The use of billon coins dates from ancient Greece and continued through the Middle Ages. During the sixth and fifth centuries BC, some cities on Lesbos used coins made of 60% copper and 40% silver. In both ancient times and the Middle Ages, leaner mixtures were adopted, with less than 2% silver content. Billon"
"trend in the 21st century toward use of coinage metals of only the least exotic and expensive types. Historically, most coinage metals (or alloys) are from the three nonradioactive members of group 11 of the periodic table: copper, silver and gold, the copper usually being augmented with tin and often other metals to form bronze. Gold, silver and bronze or copper were the coinage metals of the ancient world, and most medieval coins. All western histories of coins begin invention at some time slightly before or after 700 BC, in Aegina Island, or, according to others, in Ephesus, Lydia, 650"
"Auricupride Auricupride is a natural alloy that combines copper and gold. Its chemical formula is CuAu. The alloy crystallizes in the Cubic crystal system and occurs as malleable grains or platey masses. It is an opaque yellow with a reddish tint. It has a hardness of 3.5 and a specific gravity of 11.5. A variant called ""tetra-auricupride"" (CuAu) exists. Silver may be present resulting in the variety ""argentocuproauride"" (Cu(Au,Ag)). It was first described in 1950 for an occurrence in the Ural Mountains Russia. It occurs as low temperature ""unmixing"" product in serpentinites and as reduction ""halos"" in redbed deposits. It"
"end, goloid was rejected as a coinage metal because it could not be distinguished from the normal U.S. 90% silver coin alloy without chemical analysis, thus inviting counterfeiters to use silver-copper alloys alone to make lower-value copies. Goloid Goloid is an alloy of silver, gold and copper patented by Dr. William Wheeler Hubbell on May 22, 1877 (U.S. patent #191,146). The patent specifies 1 part gold (about 3.6%), 24 parts silver (about 87.3%), and 2.5 parts copper (about 9.1%, all by weight); however, the patent also states that ""The proportions may be slightly varied"" and goes on to specify that"
"is most often found in Chile, Argentina, Tasmania, Russia, Cyprus, Switzerland and South Africa. Auricupride Auricupride is a natural alloy that combines copper and gold. Its chemical formula is CuAu. The alloy crystallizes in the Cubic crystal system and occurs as malleable grains or platey masses. It is an opaque yellow with a reddish tint. It has a hardness of 3.5 and a specific gravity of 11.5. A variant called ""tetra-auricupride"" (CuAu) exists. Silver may be present resulting in the variety ""argentocuproauride"" (Cu(Au,Ag)). It was first described in 1950 for an occurrence in the Ural Mountains Russia. It occurs as"
"gold"", as it is usually pale yellow or yellowish-white in colour. The modern use of the term ""white gold"" usually concerns gold alloyed with any one or a combination of nickel, silver, platinum and palladium to produce a silver-coloured gold. Electrum consists primarily of gold and silver but is sometimes found with traces of platinum, copper, and other metals. The name is mostly applied informally to compositions between about 20–80% gold and 20–80% silver atoms, but these are strictly called gold or silver depending on the dominant element. Analysis of the composition of electrum in ancient Greek coinage dating from"
"were made of electrum, an alloy of gold and silver that was highly prized and abundant in that area. In the middle of the 6th century BC, King Croesus replaced the electrum coins with coins of pure gold and pure silver, called ""Croeseids"". The credit for inventing pure gold and silver coinage is attributed by Herodotus to the Lydians: The Greek world was divided into more than two thousand self-governing city-states (in Greek, ""poleis""), and more than half of them issued their own coins. Some coins circulated widely beyond their ""polis"", indicating that they were being used in inter-city trade;"
"silver and carat gold and carat solders used in the jewelry industry, modifying the color, hardness and melting point of the resulting alloys. Some lead-free solders consist of tin alloyed with a small proportion of copper and other metals. The alloy of copper and nickel, called cupronickel, is used in low-denomination coins, often for the outer cladding. The US five-cent coin (currently called a ""nickel"") consists of 75% copper and 25% nickel in homogeneous composition. The alloy of 90% copper and 10% nickel, remarkable for its resistance to corrosion, is used for various objects exposed to seawater, though it is"
"gold compound minerals are uncommon, mainly a handful of selenides and tellurides. Native silver occurs as elongated dendritic coatings or irregular masses. It may also occur as cubic, octahedral, or dodecahedral crystals. It may occur alloyed with gold as electrum. It often occurs with silver sulfide and sulfosalt minerals. Various amalgams of silver and mercury or other metals and mercury do occur rarely as minerals in nature. An example is the mineral eugenite (AgHg) and related forms. Silver nuggets, wires, and grains are relatively common, but there are also a large number of silver compound minerals owing to silver being"
"Silver mining Silver mining is the resource extraction of silver by mining. Silver is found in native form very rarely as nuggets, but more usually combined with sulfur, arsenic, antimony, or chlorine and in various ores such as argentite (AgS), chlorargyrite (""horn silver,"" AgCl), and galena (a lead ore often containing significant amounts of silver). As silver is often found in conjunction with these or alloyed with other metals such as gold, it usually must be further extracted through amalgamation or electrolysis. Silver mining has been undertaken since early times. As silver is a precious metal often used for coins,"
"as heap leaching was first proposed in 1969 by the United States Bureau of Mines, and was in use by the 1970s. Gold occurs principally as a native metal, usually alloyed to a greater or lesser extent with silver (as electrum), or sometimes with mercury (as an amalgam). Native gold can occur as sizeable nuggets, as fine grains or flakes in alluvial deposits, or as grains or microscopic particles (known as color) embedded in rock minerals. Ores in which gold occurs in chemical composition with other elements are comparatively rare. They include calaverite, sylvanite, nagyagite, petzite and krennerite. Gravity concentration"
"coins are perhaps best known from the Roman Empire, where progressive debasements of the Roman ""denarius"" and the Roman provincial ""tetradrachm"" in the second century AD led to declining silver and increasing bronze content in these denominations of coins. Eventually, by the third quarter of the second century AD, these coins were almost entirely bronze, with only a thin coating or even a wash of silver. Billon (alloy) Billon is an alloy of a precious metal (most commonly silver, but also mercury) with a majority base metal content (such as copper). It is used chiefly for making coins, medals, and"
"which are used in mining and electroplating. Gold dissolves in mercury, forming amalgam alloys, but this is not a chemical reaction. A relatively rare element, gold is a precious metal that has been used for coinage, jewelry, and other arts throughout recorded history. In the past, a gold standard was often implemented as a monetary policy, but gold coins ceased to be minted as a circulating currency in the 1930s, and the world gold standard was abandoned for a fiat currency system after 1971. A total of 186,700 tonnes of gold exists above ground, . The world consumption of new"
"of all the gold that is ascertained to exist today on Earth has been extracted from these Witwatersrand rocks. On Earth, gold is found in ores in rock formed from the Precambrian time onward. It most often occurs as a native metal, typically in a metal solid solution with silver (i.e. as a gold silver alloy). Such alloys usually have a silver content of 8–10%. Electrum is elemental gold with more than 20% silver. Electrum's color runs from golden-silvery to silvery, dependent upon the silver content. The more silver, the lower the specific gravity. Native gold occurs as very small"
"coins made in Britain dating from the end of the second century BC. They appear to have circulated mainly in Kent and were based on coins issued by Massalia (now Marseille). Potin Potin (also known as billon) is a base metal silver-like alloy used in coins. It is typically a mixture of copper, tin and lead (in varying proportions) and it is debated whether any actual silver needs to be present. While the term ""billon"" is more commonly applied to ancient Roman coinage, ""potin"" is usually used for Greek or Celtic coinage. In 1890, so-called ""Potin lumps"" were found, of"
"Goloid Goloid is an alloy of silver, gold and copper patented by Dr. William Wheeler Hubbell on May 22, 1877 (U.S. patent #191,146). The patent specifies 1 part gold (about 3.6%), 24 parts silver (about 87.3%), and 2.5 parts copper (about 9.1%, all by weight); however, the patent also states that ""The proportions may be slightly varied"" and goes on to specify that the silver portion can range from 20 times to 30 times that of the gold, and the copper could range from one-eighth to one-twelfth (from 12.5% to 8.33%) of the total mixture. The patent specifies that the"
"copper alloy was not thoroughly mixed. These counterfeits will have a slightly mottled appearance. Gold coin A gold coin is a coin that is made mostly or entirely of gold. Most gold coins minted since 1800 are 90–92% gold (22 karat), while most of today's gold bullion coins are pure gold, such as the Britannia, Canadian Maple Leaf, and American Buffalo. Alloyed gold coins, like the American Gold Eagle and South African Krugerrand, are typically 91.7% gold by weight, with the remainder being silver and copper. Traditionally (up to about the 1930s), gold coins have been circulation coins, including coin-like"
"metal ingots were found in an ancient shipwreck in Gela (Sicily), which were made of an alloy primarily consisting of copper, zinc and small percentages of nickel, lead, and iron. In numismatics, orichalcum is the golden-colored bronze alloy used by the Roman Empire for their sestertius and dupondius coins. The name is derived from the Greek , ""oreikhalkos"" (from , ""oros,"" mountain and , ""chalkos,"" copper), meaning literally ""mountain copper"". The Romans transliterated ""orichalcum"" as ""aurichalcum,"" which was thought to literally mean ""gold copper"". It is known from the writings of Cicero that the metal which they called orichalcum resembled"
"indication of their value. Most coins are circular but some were rectangular. Also a lot of coins, especially in China had a hole through the center so they could be tied on to a string. Among the earliest coins to be made purely from silver and gold were the silver Dirham and gold Dinar in the early Islamic Caliphate from the 7th century. Silver and gold coins are the most common and universally recognized throughout history, even today. Mints around the world still make millions of gold and silver coins, including the Canadian Silver Maple Leaf, the American Gold Eagle,"
"and krennerite (two different polymorphs of AuTe), petzite, AgAuTe, and sylvanite, AgAuTe. The city of Telluride, Colorado, was named in hope of a strike of gold telluride (which never materialized, though gold metal ore was found). Gold itself is usually found uncombined, but when found as a chemical compound, it is most often combined with tellurium. Although tellurium is found with gold more often than in uncombined form, it is found even more often combined as tellurides of more common metals (e.g. melonite, NiTe). Natural tellurite and tellurate minerals also occur, formed by oxidation of tellurides near the Earth's surface."
"gold was often alloyed with copper to produce red-gold, or iron to produce a bright burgundy-gold. Gold was often found alloyed with silver or other metals to produce various types of colored gold. These metals were also used to strengthen each other, for more practical purposes. Copper was often added to silver to make sterling silver, increasing its strength for use in dishes, silverware, and other practical items. Quite often, precious metals were alloyed with less valuable substances as a means to deceive buyers. Around 250 BC, Archimedes was commissioned by the King of Syracuse to find a way to"
"metals except gold and platinum. This procedure refines gold directly, producing up to 99.5% purity gold powder in a single step. Gold parting Gold parting is the separating of gold from silver. Gold and silver are often extracted from the same ores and are chemically similar and therefore hard to separate. Over the centuries special means of separation have been invented. The very earliest precious metals had mixes of gold and silver; gold and silver alloy is called electrum. With the advent of coinage, methods had to be invented to remove impurities from the gold so that gold of specific"
"action to form nuggets. Gold sometimes occurs combined with tellurium as the minerals calaverite, krennerite, nagyagite, petzite and sylvanite (see telluride minerals), and as the rare bismuthide maldonite (AuBi) and antimonide aurostibite (AuSb). Gold also occurs in rare alloys with copper, lead, and mercury: the minerals auricupride (CuAu), novodneprite (AuPb) and weishanite ((Au, Ag)Hg). Recent research suggests that microbes can sometimes play an important role in forming gold deposits, transporting and precipitating gold to form grains and nuggets that collect in alluvial deposits. Another recent study has claimed water in faults vaporizes during an earthquake, depositing gold. When an earthquake"
"antimony, and bismuth. Native chromium has been found in small grains in Sichuan, China and other locations. Native metal A native metal is any metal that is found pure in its metallic form in nature. Metals that can be found as native deposits singly or in alloys include aluminium, antimony, arsenic, bismuth, cadmium, chromium, cobalt, indium, iron, manganese, molybdenum, nickel, rhenium, selenium, tantalum, tellurium, tin, titanium, tungsten, vanadium, and zinc, as well as two groups of metals: the gold group, and the platinum group. The gold group consists of gold, copper, lead, aluminium, mercury, and silver. The platinum group consists"
"1971 Nixon shock, since when all of the world's currencies have operated as more or less freely floating fiat money, unconnected to the value of silver or gold. Nonetheless, academics continue to inconclusively debate the relative use of the metallic standards. From the 7th century BCE, Asia Minor, especially in the areas of Lydia and Ionia, is known to have created a coinage based on electrum, a natural occurring material called electrum, a variable mix of gold and silver (with about 54% gold and 44% silver). Before Croesus, his father Alyattes had already started to mint various types of non-standardized"
"Potin Potin (also known as billon) is a base metal silver-like alloy used in coins. It is typically a mixture of copper, tin and lead (in varying proportions) and it is debated whether any actual silver needs to be present. While the term ""billon"" is more commonly applied to ancient Roman coinage, ""potin"" is usually used for Greek or Celtic coinage. In 1890, so-called ""Potin lumps"" were found, of which the largest weighs at the Prehistoric pile dwelling settlement ""Alpenquai"" in Zürich (""Vicus Turicum"") in Switzerland. The pieces consist of a large number of fused Celtic coins, which are mixed"
"gold. When viewed through a microscope, voids appear where the copper and silver had been. In 1992, approximately 200 silver ""tumbaga"" bars were recovered in wreckage off Grand Bahama Island. They were composed mainly of silver, copper, and gold plundered by the Spaniards during the conquests of Cortés and hastily melted into bars of tumbaga for transport across the Atlantic. Such bars were typically melted back into their constituent metals in Spain. Tumbaga Tumbaga is the name for a non-specific alloy of gold and copper given by Spanish Conquistadors to metals composed of these elements found in widespread use in"
"Metals of antiquity The metals of antiquity are the seven metals which humans had identified and found use for in prehistoric times: gold, silver, copper, tin, lead, iron, and mercury. These seven are the metals from which the modern world was forged; until the discovery of arsenic in the 13th century, these were the only known elemental metals, compared to the 86 known today. The metals of antiquity generally have low melting points, with iron being the exception. While all the metals of antiquity but tin and lead occur natively, only gold and silver are commonly found as the native"
"gold and pure silver or the first precious metal coins in general. Despite this ambiguity, this statement of Herodotus is one of the pieces of evidence most often cited on behalf of the argument that Lydians invented coinage, at least in the West, although though the first coins (under Alyattes I, reigned c.591–c.560 BC) were neither gold nor silver but an alloy of the two called electrum. The dating of these first stamped coins is one of the most frequently debated topics of ancient numismatics, with dates ranging from 700 BC to 550 BC, but the most common opinion is"
"and tin, to form amalgams (an alloy in a soft paste or liquid form at ambient temperature). Amalgams have been used since 200 BC in China for gilding objects such as armor and mirrors with precious metals. The ancient Romans often used mercury-tin amalgams for gilding their armor. The amalgam was applied as a paste and then heated until the mercury vaporized, leaving the gold, silver, or tin behind. Mercury was often used in mining, to extract precious metals like gold and silver from their ores. Many ancient civilizations alloyed metals for purely aesthetic purposes. In ancient Egypt and Mycenae,"
"metal is used in many bullion coins, sometimes alongside gold: while it is more abundant than gold, it is much less abundant as a native metal. Its purity is typically measured on a per-mille basis; a 94%-pure alloy is described as ""0.940 fine"". As one of the seven metals of antiquity, silver has had an enduring role in most human cultures. Other than in currency and as an investment medium (coins and bullion), silver is used in solar panels, water filtration, jewellery, ornaments, high-value tableware and utensils (hence the term silverware), in electrical contacts and conductors, in specialized mirrors, window"