Gold or gold with the chemical symbol Au is the name of a soft and malleable element with a bright and shiny yellow color that does not rust or darken in the vicinity of air and water. Chemically, gold is an intermediary metal that is in group 11 of the periodic table and is one of the least reactive solid elements under standard conditions.
This metal can be found in pure form in nature in the form of grains or pieces among rocks, veins and sediments. Gold can also be seen as a solid solution with other elements such as silver (electrum), in the form of an alloy with metals such as copper and palladium, and even as inclusions and trapped among materials such as pyrite. In unusual cases, gold has also been observed combined with elements such as tellurium.
The chemical symbol of this element, Au, is derived from its Latin name, aurum, which means “dawn glow”.
The value of gold is due to its rarity, easy usability, easy purification, resistance to rust and corrosion, distinctive color, non-reactivity with other elements; Features that are rarely seen in other metals. Also, this metal has the ability to reach very small strands, which is a very important property in making jewelry. Since the beginning of human written history, gold has always been a precious and popular metal that has been used for minting coins, making jewelry, and artistic applications. In the past, the financial policy of many countries was based on the gold standard, which means that the currency of each country was equivalent to a certain amount of gold. The gold standard was abandoned from the beginning of World War I in most European countries and gradually in other countries after that, and it was replaced by a loose monetary policy.
In addition to capital use and use in jewelry, gold has various other uses, such as: dentistry, production of colored glass and electronic industries, and due to its high electrical conductivity, gold is used in electrical wiring.
According to estimates, a total of 174,000 tons of gold have been mined throughout human history until 2012. (5) equivalent to 5.6 billion troy ounces and equivalent to 9,015 cubic meters in terms of volume, of which, according to estimates, 50% is in the form of jewelry, 40% in the form of ingots and coins for investment in the official gold reserves of central banks and investment funds and personal capital, and about 10% is kept in the industry sector.
Global gold production in 2011 was about 2,700 tons, which has increased compared to 2,260 tons in 2008. Since the 1880s, a large part of the world’s gold production has been done in South Africa. About half of all gold ever mined has come from South Africa, and from 1905 to 2007, the country consistently topped the list of gold producers. In 1970, this country had 1,480 tons of gold equivalent to 79% of the total world gold production. South Africa’s share in gold production has decreased drastically in recent years. China is by far the largest gold producer in the world with an annual production of 440 tons of gold by 2017.
India has been the largest importer of gold in recent decades due to the high demand for gold jewelery in the country. It is estimated that 18 thousand tons of gold are kept in the homes of Indians. However, in 2013, gold demand in China surpassed that of India. The unit of measurement of gold in the global market is troy ounce equal to 31.1 grams. The price of gold in July 2020 was equivalent to $1,800 per ounce, which is equivalent to about $58,000 per kilogram.
Gold is stable against most acids, but it dissolves in Soltani acid (nitro-hydrochloric acid). In addition, gold dissolves in alkaline solutions of cyanide, which is used in mining, and in mercury by making amalgam alloys. Nitric acid, which has the ability to dissolve silver and base metals, is powerless against gold. This characteristic of nitric acid is used in the acid test to identify and verify gold.
Gold is usually used as an alloy with other metals. Copper is the most common metal for making gold alloy, and sometimes other metals such as silver, nickel, and palladium are also used. The percentage of gold present in each metal object is called gold grade, which is usually expressed in 24 units or 1000 units; For example, 18 carat gold (750) contains 75% gold and 900 gold contains 90% gold.