Pure gold is incorruptible, that is not rust, is eternal, immutable, uniform, easily transportable.
Only around 1700 it was discovered the first gold reagent, a mixture of hydrochloric acid and nitric acid that could dissolve. But his legend was not the least destabilized, indeed almost to emphasize its uniqueness, the reagent was given the name "aqua regia".
Today we know the solubility of gold in sodium cyanide (NaCN) and potassium (KCN), which is the basis of the cyanidation process, which separates the gold from the other components and the end of the nineteenth century. was greatly enrich the South African mining industry (note that the solutions cyanides cause serious burns of the skin).
Gold is also a good conductor of heat and electricity is melted at a temperature of 1064 ° C. Its density (specific gravity) is only 19.3 gr/cm3 and metals of the platinum group are heavier gold.
Along with copper and silver form a particular subgroup of elements having a similar composition of the atom is of some chemical properties: this is because in nature there is often gold with silver or copper. It is no coincidence these minerals have
acted as money.
Other chemical instead of gold makes it similar to osmium, iridium and platinum, which, together with ruthenium, palladium and radio, are called "noble" for their chemical inertness, which makes them stainless. The most important from an economic point of view is platinum.
Gold is present everywhere, often mixed with a score of different minerals: it is in any terrain, in any ganga, in seawater, but in most cases the rate of concentration is very least.
On average, one tonne of the Earth's crust contains, according to some calculations, 4 milligrams of yellow metal, that is thousands of times less than copper, zinc or lead. In this respect, the meteorites (whose chemical composition is similar to that of deeper layers of the Earth) contains more gold of the earth's crust.
According to other calculations, in order to obtain an ounce of gold, that is 31.1035 degrees, medium is necessary to remove and grind over 5 tons of rock. At the end of this round gold is not yet pure; accompanying silver, copper, lead, zinc or platinum and, since its marketing has to be a purity of 99.5%, the gold undergoes further steps that separate it from any presence alien:
1. levigated (the raw material is crushed and subjected to strong jets of water in special containers in order to separate it from other minerals: the gangue), 2. cyanidation (the ore is treated with a cyanide alkaline salts are formed from these complexes and the gold is extracted), 3. amalgamation (the ore is finely ground and treated with mercury, which forms an amalgam with them, holding it while the rest of the ore remains unchanged; distillation at a later time the amalgam is obtained gold) 4. refining (the ore is treated with substances such as sulfuric acid, nitric acid or chlorine, separating the gold from the rest of the material). Much of the origin of all these processes lies in the Egyptian civilization of 3,000 years ago.
The vast majority of gold is not extracted in the form of pepita, but in mine, mixed with other minerals, or powders near the Earth's surface, near rivers etc. (alluvial deposits).
Pure Gold is a very soft metal. For this reason you do not make jewelry in pure gold: it will consume very quickly. The metals that bind with the pure gold are different: silver, copper and palladium are the most used. The evaluation is related to the quantity of precious metal and second metal present.
Surprising is the ductility of gold, that is the docility with which you let cut in thin wires, from a single gram has been a long wire over 3,500 m. No less spectacular is its malleability: it is technically possible to fly an ounce of gold as to obtain a sheet with an area of 16 sqm. A wafer may have a thickness impalpable, up to 0.2 micron (millionth of a meter).
Leagues and titles
Being a gold metal tenero, alone can not be used in the manufacture of jewelry because it is not guaranteed durability. Here's why it is always associated with other metals that give it the necessary firmness: the different combinations of gold with other metals are called alloys.
The metals most commonly used to make gold jewelry are fabricated in copper, silver, palladium and a few others. The clever blend of gold with other metals, it gives a different color shades of yellow solar dall'originario fact that the colors are alternated periodically to the forefront of fashion can be obtained through appropriate dosages in the formulation of the alloy:
Yellow gold silver and copper
Pale yellow: very little copper silver
Gold rose very little copper silver
Red gold: copper
White gold: palladium
Green gold: silver
Gold lilac: Aluminum
Gold blue: cobalt
Alloys are different both in terms of metals that are associated with gold both in terms of the quantity of gold used and the relationship between the quantity of gold and other metals in the alloy is called Title.
The title is expressed in milliseconds, is the amount of gold present in the alloy (combination with other metals) which is composed of the jewel in milliseconds per gram.
The carat is a unit of measurement equivalent to 41.6 thousandths of a gram of gold in the alloy. For example, the Italian gold that is almost always a 18-carat is equivalent to the presence of 750 parts of gold to 250 parts of the metal in 1000 parts of alloy which is the jewel: just a 18-carat. In many countries, uses a lighter caratura: It ranges from 9 carats of poor countries to 14 countries such as France and England. This means that one has less gold jewelry, and thus costs less.
Below are listed with both definitions of the titles most commonly used for the creation of jewels:
8 carats = 333 thousandths of a gram
12 karat = 500 thousandths of a gram
14 karat = 585 thousandths of a gram
18 karat = 750 thousandths of a gram
22 karat = 916 thousandths of a gram
24 karat = 999 thousandths of a gram
The most used is that of 18 carat. But on the bullion held in banks is also the title 999.
The law requires that every building on the gold producer affix a special stamp with the title of the league, whose veracity is fully responsible. The punches that in Italy, must appear on each object in gold are: what is the title and one that represents the identification of the manufacturer.
A question mark: why the gold used (scrap) that is less than the price of the day?
Because the price of the day is pure gold, then gold has come under 999 milliseconds, while items that are on the market are linked to 750 milliseconds, thus already entitled to the difference in price is lowered.
Furthermore, the items in time lose some 'pure gold, then 750 milliseconds, you can go down to 740/730 milliseconds.
And always be assessed the amount of gold that we are actually buying, not working, which is worth a party.