gold bullion/bar is a gold ingot which may be produced
in many different types, weights and categories.
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.
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.
tonne = 1000 kilograms = 32,150.746 troy ounces (value US$19,290,000).
kilogram = 1000 grams = 32.15074656 troy ounces (value US$19,290.44).
tael = 50 grams (value US$964.50).
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
WHAT IS A HALLMARK?
of a series of marks applied to an article of precious metal
the article has been independently tested
that it conforms to all legal standards of purity (fineness)
A complete hallmark consists
of three compulsory punch marks:
Assay Office London also applies
two optional marks, at no extra cost:
- Date mark
- Traditional fineness mark
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).
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
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 (92% Purity)
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
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
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
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
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
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.
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.
Encyclopedia Britannica, National Mining Association