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Gold Bullion Bar
GOLD Bullion/Bar
A gold bullion/bar is a gold ingot which may be produced in many different types, weights and categories.

Types

Gold bars are classified into two different classes — cast and minted — based on their method of manufacturing. Cast bars are made by pouring molten gold into an ingot mold to help the gold to take a form. Minted bars are made from gold blanks that have been hand cut to the required dimensions from a flat piece of gold. Markings are almost always applied by presses.

Weights and Values

One troy ounce = 31.1034768 grams. Thus if gold was at US$600 per ounce, a gold gram would be worth just under US$20.Note where gold is measured in ounces, these are troy ounces, not the much more common avoirdupois ounce which is used for measuring weights in food etc. An avoirdupois ounce is lighter than a troy ounce. One avoirdupois ounce = 28.349523125 grams.
  • One tonne = 1000 kilograms = 32,150.746 troy ounces (value US$19,290,000).
  • One kilogram = 1000 grams = 32.15074656 troy ounces (value US$19,290.44).
  • One tael = 50 grams (value US$964.50).

Beware, this is the official rate of taels in mainland China since the country went metric. However, historically a tael's weight could be as little as 36.7 grams depending on the customs of the province. In Taiwan and Hong Kong today a tael is equivalent to 37.429g.The current value of gold places a price of approximately $241,000 on a 12.5 kg (400 troy ounces) (London Good Delivery) bar of gold.Gold is very dense (19.3 g/cm3), to the extent that ten million U.S. dollars worth occupies less than one cubic foot.

Hallmarks

WHAT IS A HALLMARK?

A hallmark:

  • Consists of a series of marks applied to an article of precious metal
  • Means that the article has been independently tested
  • Guarantees that it conforms to all legal standards of purity (fineness)

A complete hallmark consists of three compulsory punch marks:

  • Sponsor's (or maker's or manufacturer's or name) mark
  • Metal and fineness (purity) mark
  • Assay office mark

Assay Office London also applies two optional marks, at no extra cost:

  • Date mark
  • Traditional fineness mark

OTHER MARKS

Other marks can be applied, eg commemorative or international convention marks (examplea on Convention Brochure - click here, and for LBMA accepted assayers and refinery hallmarks, click here).

WHY HALLMARK?

Precious metals are rarely used in their purest form but are usually alloyed with other metals. It isn't possible to detect an article's precious metal content by sight or touch. Therefore, it is a legal requirement to hallmark articles containing precious metals if they are described as such.

The UK Hallmarking Act (1973) - click here for copy, states that it is an offence for any person, in the course of trade or business, to describe an un-hallmarked article as being wholly or partly made of precious metal(s) or to supply un-hallmarked articles to which such a description is applied.

Dealers are required to display on their premises the statutory notice which describes the approved hallmarks. It is an offence for any dealer to fail to exhibit or keep exhibited the notice. 'Dealer' means a person engaged in the business of making, supplying, selling (including selling by auction) or exchanging articles of precious metal or in other dealings in such articles. The dealers' notice can be downloaded from here courtesy of the Goldsmith Company - Assay Office London.

 
Gold Dust
   
Gold Dory Bar
Alluvial GOLD Dust (92% Purity)
GOLD Dory Bar (92% Purity)

Alluvial gold refers to fine particles of elemental gold found in riverbeds, streambeds, and floodplains. Alluvial deposits are either dredged from pond and river bottoms or sluiced from banks and floodplains with high-pressure hydraulic hoses. They are usually concentrated by gravity techniques and require little or no comminution.

An alluvial gold dust buyer will then assay the elemental gold before releasing it for refining. Gold refining begins with amalgamation or cyanidation.

Amalgamation is the process of combining gold ore with mercury by either slurry mixing techniques or grinding. The resulting amalgam is heated to distill off the mercury.

Cyanidation is a process of oxidizing gold and dissolving it in an alkaline cyanide solution, based on the Elsner reaction, to allow the gold-bearing solution to be separated from the solids. This is accomplished for higher grade ores in large tanks (vat leaching) or for low-grade ores, by spraying a dilute cyanide solution over the ore (heap leaching).

Granular activated carbon can be added to the ore slurry during or upon the completion of gold solubilization to remove it from the solution. Gold is then leached by chemical solution or deoxygenation and filtering. Gold ores not amenable to cyanidation (refractory ores) can be treated with various oxidizing processes, using high temperature and high pressure to remove interfering substances prior to cyanidation.

Gold extracted by amalgamation or cyanidation is then melted into gold dore’ bars of about 90-94 percent purity. The gold dust buyer or gold dore’ purchaser then transports the bars to a refinery for further refining.

Using the Miller process, the gold is melted and gaseous chlorine is blown onto the liquid, causing impurities to form chloride compounds that separate into a layer on the surface of the gold. This produces gold bars of 99.5 percent purity.

The gold is further refined by the Wohlwill process, which uses electrolysis with a hydrochloric acid/gold chloride solution, or by a wet chemical process using a nitric acid/hydrochloric acid mixture, to produce gold bars of 99.99 percent purity.

Alluvial gold mining in West Africa dates back several thousand years. In ancient times, gold was mined from alluvial placers—that is, fine particles of elemental gold found in river sands. The gold was concentrated by washing away the lighter river sands with water, leaving behind the dense gold particles, which could be melted and made into coins and decorative objects (statuary, jewelry, weapons, and goblets).
Early explorers to West Africa noted the incredible wealth of gold ornaments worn by tribal leaders, and were eager to establish trade with them. As early as the 10th century, gold au purchasers bought gold and gold dust from Ghana, Mali and Songhai and imported it to Europe by caravan.

In 1471, Portuguese explorers discovered alluvial gold deposits in the mouth of the Pra River, and the West African coast quickly became a prosperous destination for Portuguese entrepreneurs and gold dust buyers. The Portuguese were soon followed by English, Spanish, Dutch, Danish and French mining companies and alluvial gold purchasers. Placer deposits were dispersed in river gravel throughout the coastal region. It is estimated that from 1471 to 1880, more that 14.4 million ounces, representing more than 443 tons of gold were produced, leading to the area being named the Gold Coast.
The gold trade was brisk in the 15th and 16th centuries, declined in the 18th century with the advent of the slave trade, and revived in the 19th century when slavery was abolished and commercial mining of gold was established. Between 1901 and 1957, the Gold Coast was declared an official colony of Great Britain, which invested a substantial amount of capital into the infrastructure of the region in the forms of railways, ports, and hydroelectric projects to facilitate mining and transport of alluvial gold and gold dore’ to buyers in Europe.

Currently West Africa is one of the fastest growing gold producing regions in the world. Gold au purchasers are a driving force behind foreign and local exploration in the region, which is estimated to contain some of the largest undeveloped gold deposits in the world. Over the last ten years, numerous junior and independent gold mining exploration companies have produced significant amounts of alluvial gold dust and gold dore’ in Ghana and Mali. Liberia, Guinea, Sierra Leone and Senagal are moving into the gold mining industry as well. Good geology, modernization of mining codes, technological improvements, and government support in the region have created a boon for alluvial gold dust and gold dore’ buyers.

Sources: Encyclopedia Britannica, National Mining Association
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