GOLD
gold - mineral 1.1.1.1

The Mineral and Gemstone Kingdom   Help   Pictures
Help Chemical Formula Au
Help Composition Gold, with small amounts of silver; sometimes also copper and iron
Help Variable Formula (Au,Ag) ;
(Au,Ag,Cu,Fe)
Help Color Golden yellow to brass yellow
Help Streak Golden yellow
Help Hardness 2½ - 3
Help Crystal Forms
and Aggregates
(Isometric) Octahedral, dodecahedral, and cubic crystals occur. Crystals are very uncommon and are usually distorted. Dendrites, wires, nuggets, and small flakes are more common.
Help Transparency Opaque
Help Specific Gravity 15.5 - 19.3 (100% pure Au = 19.3)
Help Luster Metallic
Help Cleavage None
Help Fracture Hackly
Help Tenacity Ductile and malleable
Help Other ID Marks Excellent conductor of electricity
Help Other Names Native Gold
Help Varieties Picture Rock - Mixture of Gold and Quartz found in gold yielding quartz veins.
Electrum -
Alloy of silver and gold, with the gold content about 75%.
Help In Group Native elements ; Metallic elements
All About The mineral Gold is almost always mixed with a small amount of silver, and sometimes contains traces of copper and iron. A Gold nugget is usually 70 - 90 percent gold, and the remainder mostly silver. The color of pure Gold is bright golden yellow, but the greater the silver content, the whiter the color.

Most Gold is mined from
ore, containing tiny amounts of Gold in the ore. The ore is brown, iron-stained rock or massive white Quartz. To extract the gold, the ore is crushed, then the gold is separated from the ore by various methods.
Gold is less commonly found as nuggets. Nuggets are formed when erosion causes a large piece of Gold to separate from its mother rock, and then gets carried away into a stream or river. The flowing water tumbles the Gold, giving each specimen a distinct shape. The Gold eventually settles at the bottom of the water, and due to its heaviness remains there. Other nuggets also get caught in the same area, forming a
placer deposit.

An even rarer form of Gold is as crystals, which are
cubic, octahedral, and dodecahedral. Even when the Gold occurs in crystals, they are distorted or are almost microscopic.

The finest Gold specimens that have been found since early times have been smelted for production. Nice specimens, therefore, are regarded very highly, and are worth much more than the standard gold value.

Gold is one of the heaviest minerals, and therefore can be panned easily because the Gold sinks to the bottom, below the other substances. In addition, it can be easily separated from other substances due to the weight differences.
Gold is the most
malleable and ductile substance known. It can be flattened out to less than .00001 of an inch (less than .000065 cm) and a 1 oz. (28 gram) mass can stretch out to a distance of over 50 miles (75 kilometers)!
Gold is also one of the most
resistant metals. It won't tarnish, discolor, crumble, or be affected by most solvents. This adds on to the uniqueness of this mineral.

Gold is usually associated with
Pyrite and other sulfides, and many times cannot be noticed because of the association with these resembling minerals. In certain localities, minerals that contain these sulfides are heated high enough for the sulfides to depart, enabling the Gold to remain intact on the matrix. Such Gold is known as "Roasted Gold", and is occasionally sold in "rock shops".
Help Uses Gold has been used as a precious metal throughout the history of mankind. This is due to its resistance, beauty, rareness, and the fact that it is very easy to work with. In addition, in the olden days gold didn't have to be extracted, because a large amount was found in a pure state. Many gold ornaments from the past have been found. Most noted are from the tombs of the Pharaoh in Egypt, where gold masks, statues, coins, and much jewelry was archeologically excavated. Gold has been used for coinage throughout the centuries, and is currently accepted internationally as a standard value. Nowadays the main use of gold is for jewelry.

Due to gold's distinctive properties as a metal, it has several industrial uses. It is also used for photography, dentistry, coloring, and being studied for treatments in cancer.


Also see the gemstone section on Gold
Help Striking Features Golden-yellow color, extreme heaviness, lack of tarnish, and extreme malleability and ductility
Help Complex Tests Soluble only in aqua regia
Help Popularity (1-4) 1
Help Prevalence (1-3) 3
Help Demand (1-3) 1
Distinguishing
Similar Minerals
Pyrite and Marcasite - different streak (black), less dense (4.8 - 5.2), harder (6 - 6½)
Chalcopyrite - different streak (black), less dense (4.1 - 4.3), harder (3½ - 4)

Only tiny flakes or crystals of these three minerals can possibly be confused with Gold, because the differences are easily noticed. These minerals are more pale than Gold, but occasionally exhibit a more intense yellow like Gold.
Help Commonly
Occurs With
Quartz, Pyrite, Arsenopyrite, Silver
Help Noteworthy
Localities
Although Gold is a rare mineral, it has many scattered occurrences. Most of these occurrences usually lack quality and quantity in regard to Gold. However, certain regions contribute greatly to the gold market. Some of the best known Gold producing regions are: California, Colorado, Ontario, Mexico, Australia, Hungary, and South Africa (the largest producer). Some famous American mines include the Empire Mine and Red Ledge Mine in Grass Valley (Washington Co.), California. Very nice crystals and crusts have been found near Ouray, Ouray Co., and in Red Mountain Pass, San Juan Co., Colorado. The Hollinger mine, along with other mines in that area of the Porcupine District, have produced large amounts of Gold.
Help Picture Icon
Links
1. Roasted Gold
Help Picture Links 1. Roasted Gold

Additional references


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