Facts about gold

A few cutouts from our CD "Guldgrävning"

Gold is a chemical element, which means it is a pure chemical substance, only containing gold. it is not a mixture of other substances. Gold is a noble metal, because of this it does not oxidize in the air as iron(it rusts) or copper(verdigris) does.

It is extremely resilient to common acids and is almost not affected by them at all. There do however exist an acid that works on gold and that is aqua regia, a mix of 1 part nitric acid and 3 parts hydrochloric acid. Gold can also be affected by potassium cyanide and sodium cyanide under certain circumstances. These are chemicals that are not to be trifled with.

Pure Gold is quiet a soft metal. The hardness of gold is 2 ½ on Mohs scale of mineral hardness.

The malleability of gold is the greatest of all metals. One gram of gold can be drawn into a 3000 meter long wire with a diameter of only 0.00012 mm! Gold can also be rolled out to a thin "sheet", so-called gold leaf, whit a thickness of only 0.0001mm! Gold leafs are so thin that light can penetrate it.

Gold is one of the heaviest metals. the mass density is 19,32. This means that if you where to fill a 2-liter milk container whit gold it would almost 40 kg! Gold is almost twice as heavy as lead.

The Latin name of gold is Aurum - which means shining dawn- this is where it got it's chemical name(AU).

The crystal form of gold is cubic. it is however unusual to find cubic crystals of gold in nature. Grains and nuggets that have been found through panning are almost always smooth rounded and slightly flattened. but there are also other more unusual forms. for example, so-called "mature gold" or dendritic gold. 

The electrical properties of gold are quiet unique. Electrostatic potential is high, +1.5 Volt. Gold's ability to conduct electric current is very good, 42,6 x 106 Siemens/m.

The melting point of gold is 1036°C.

The gold content is measured in carats or in millesimal fineness, pure gold = 24 carats or 1.000 fine(three nines fine?) 

Gold can be alloyed (melted together) with other metals such as silver or copper. If the alloy contains 75% gold, then the gold content becomes 18 carats or 750 fine. if the alloy contains 50% gold then the cold content becomes 12 carats or 500 fine, and so forth. Using pure gold (24 carats) for ordinary purposes is impractical. Therefore gold is often alloyed with copper, so that the alloy for example becomes harder and more durable. Gold that is naturally alloyed with at least 20% silver is called electrum.

The atomic number of gold is 79, its atomic weight is 197 and the oxidation is +I and +II. 

Internationally gold is weighted in troy ounces. one troy ounce is 31.1 grams. The value of gold is determined daily on the major metal exchanges in London, Tokyo and New York and is counted in U.S. dollars/troy ounce. in march of 2008 the price of one gram of gold was - translated to Swedish Kronor- approximately 179:- + VAT(179.000:-/kg + VAT). Gold bars are stored in large bank vaults that is called gold reserves.

The largest part of all gold that have been unearthed is used for jewelry. Some of it is also used in dentistry and the rest goes to for instance the electronic industry. In nature gold occurs as both grains and nuggets in the watercourse bottom sediment and as rock gold in veins. 

In air gold weight 6-7 times as much as what sand and gravel does. However, under water gold weight 10-11 times as much as what sand and gravel does. This can be explained by means of Archimedes' famous principle. It makes it a little easier to pan for gold in water.

The mean concentration of gold here on Earth is 3.5 milligrams per tonne. A natural (and usually somewhat flat) grain of gold, which is about 0.6 mm in diameter, weighs about 3.5 milligrams.

Our planet contains about 21.000.000.000.000 tons of gold. That is no small amount. In the crust, down to about 36 km, there are no less than 84.000.000.000 tons of gold.

A cubic kilometer of seawater contains 3.5 kg of gold.

Currently there is about 100,000 tonnes of gold in circulation. This is "everything" that have been broken and  identified so far. This corresponds to a gold cube with 17 m sides. (17 X 17 X 17 m)

A nugget -Holtermann nugget- that were found in Australia where weighing roughly 285 kg, of which 214 kg was pure gold.

No other metal can completely replace gold!