Gold is known to mankind for a long time. It was always used as means of calculation. Prior to World War I all world currencies were tied to gold. What represents this "magic" mineral?
Instruction
1. Gold is a mineral which is called "precious metal". Gold forms unlimited solid solutions with other metals, for example, silver. Based on the ratio of gold and silver emit native gold in which the content of silver reaches 30%. Also formation of gold with copper impurity – coppery gold is known (copper to 20%). There is a gold with palladium content – palladisty gold (porpetsit, up to 11% of palladium).
2. The formula of gold is Au. Color can be from pale yellow to reddish. It depends on the content of impurity. In powder color at gold golden-yellow with metal gloss. Average hardness of gold – 2.5-3. Specific weight of mineral – 15.5-19.3 g/cm3.
3. Gold has various properties. It has big malleability, differs high warm and conductivity, is not dissolved in acids (an exception – the royal vodka, hydrocianic acid and reagents emitting bromine and chlorine).
4. In a crystal form gold meets quite seldom. Sometimes it forms octahedrons, rombododekaedra, cubes. But gold in the form of grains of irregular shape which are in ore (or quartz) weight is most often observed. The sizes of grains are various, usually microscopic. The planes of its sides uneven, dim, shaded. Doubles and joints are characteristic of formation of gold.
5. Distinctive signs of gold – golden-yellow color, metal gloss, malleability, softness (is easily knifed), the big specific weight and resistance to oxidation in superficial conditions.
6. Gold can be found in the hydrothermal fields formed of volcanic breeds of sour and average structure. Especially large-scale deposits are located in terrigenous thicknesses. The largest field of gold ore is in the Republic of South Africa – Witwatersrand (Republic of South Africa). It is formed in metamorfizovanny conglomerates and initially represented a placer.
7. Gold owing to the properties has many scopes of application, both technical, and financial character. Today world reserves of gold are distributed approximately as follows: gold reserves of the countries – 45%, jewelry and ingots in a private property – 45%, industrial products – 10%.