Gold is a natural forming metal in which its natural state offers an unequalled stability and beauty. Moreover, its malleability permits to manufacture of almost transparently thin leaves, while from one ounce of gold it is possible to draw a fine wire of fifty miles long. The ductility of gold diminishes in relation to the amount of other metals alloyed with it. Its melting point is between 1832 and 1940 F; it is not subject to normal oxidization and is insoluble in nearly all common acids. The density of gold is about 19.3 times the weight of an equal volume of water and about 3 times of an Iron in the same size.
Although present in very short measure in almost all rocks, in the sea and rivers, in sand and even in plants, the areas which are rich in gold are few and scattered throughout the world. Mainly it comes from the deepest recesses of the earth and is probably the first known to man. Layers of gold are easy to reach near the earth’s surface. By mining process it will come out from earth. Raw gold is known as ‘Nugget’, & the gold found from river beds called ‘Alluvial’.
Gold was first found in India (when it’s called Hindustan), before millions of years ago. There is no proper history available for the mining of gold, but before more than 10000 million years ago the Indians were familiar with gold. The Indians introduced the entire world about the art of jewellery, metals & metal working. As the world history first use of gold had been traced back to 4000 years B.C. The Egyptians and Romans are developed gold fever, using it for coins & jewellery ornamentation. No more earliest history of any culture, that says they knew about gold before more than 4000 years. But as Indian history before millions of years ago Indians were had gold coins (called Suvarna Mudrica or Sona-Mohar), exclusive gold jewelleries and gold utensils.
Whereas most other pure metals are gray or silvery white, gold is yellow. This color is determined by the density of loosely bound (valence) electrons; those electrons oscillate as a collective "plasma" medium described in terms of a quasiparticle called Plasmon. The frequency of these oscillations lies in the ultraviolet range for most metals, but it falls into the visible range for gold due to subtle relativistic effects that affect the orbitals around gold atoms. Similar effects impart a golden hue to metallic cesium.
Common colored gold alloys such as rose gold can be created by the addition of various amounts of copper and silver, as indicated in the triangular diagram to the left. Alloys containing palladium or nickel are also important in commercial jewelry as these produce white gold alloys. Less commonly, addition of manganese, aluminum, iron, indium and other elements can produce more unusual colors of gold for various applications.
Pure gold is too soft for practical uses, but as an alloy with base metals for used in jewellery. Silver, copper or other metals are usually main base metals for alloying for ordinary purposes as jewellery or coins. Gold is basically yellow (golden) coloured metal, but when alloyed with different metals it appears different colours like whitish (called White Gold), greenish (Green Gold), reddish (Red Gold), bluish (Blue Gold), pinkish (Pink Gold). Purity of Gold is known as “Karat”. 100% pure Gold is called 24 karat fine or 100 touches Gold. After alloying with other metals, gold purity will decreases to 22, 18, 16, 14 karat etc… Gold above 18 karat is used for special work like only Gold Jewellery, Kundan Jewellery, Thewa Jewellery, Statues etc…, other purities used for diamonds & gem-stones studded Jewellery. Gold is used in International market as a currency too.
Gold is also used for medicine as a best health tonic, in food & drinks, other industries & electronic field. Because of it is an inert metal also used for covering costly parts of machinery & satellites.
Gold has been widely used throughout the world as a vehicle for monetary exchange, either by issuance and recognition of gold coins or other bare metal quantities, or through gold-convertible paper instruments by establishing gold standards in which the total value of issued money is represented in a store of gold reserves.
Pure gold is too soft for day-to-day monetary use and is typically hardened by alloying with copper, silver or other base metals. The gold content of alloys is measured in Karats (k). Pure gold is designated as 24k. English gold coins intended for circulation from 1526 into the 1930s were typically a standard 22k alloy called crown gold, for hardness (American gold coins for circulation after 1837 contained the slightly lower amount of 0.900 fine gold, or 21.6 kt).
Many holders of gold store it in form of bullion coins or bars as a hedge against inflation or other economic disruptions. However, some economists do not believe gold serves as a hedge against inflation or currency depreciation.
Because of the softness of pure (24k) gold, it is usually alloyed with base metals for use in jewelry, altering its hardness and ductility, melting point, color and other properties. Alloys with lower Karatage, typically 22k, 18k, 14k or 10k, contain higher percentages of copper, or other base metals or silver or palladium in the alloy. Copper and Silver are the most commonly used base metal.
In medieval times, gold was often seen as beneficial for the health, in the belief that something that rare and beautiful could not be anything but healthy. Even some modern esotericistsand forms of alternative medicine assign metallic gold a healing power. Some gold salts do have anti-inflammatory properties and are used as pharmaceuticals in the treatment of arthritis and other similar conditions. However, only salts and radioisotopes of gold are of pharmacological value, as elemental (metallic) gold is inert to all chemicals it encounters inside the body. In modern times, injectable gold has been proven to help to reduce the pain and swelling of rheumatoid arthritis and tuberculosis.
§ Gold can be made into thread and used in embroidery.
§ Gold produces a deep, intense red color when used as a coloring agent in cranberry glass.
§ In photography, gold toners are used to shift the color of silver bromide black-and-white prints towards brown or blue tones, or to increase their stability. Used on sepia-toned prints, gold toners produce red tones. Kodak published formulas for several types of gold toners, which use gold as the chloride.
§ As gold is a good reflector of electromagnetic radiation such as infrared and visible light as well as radio waves, it is used for the protective coatings on many artificial satellites, in infrared protective faceplates in thermal protection suits and astronauts' helmets and in electronic warfare planes.
§ Gold is used as the reflective layer on some high-end CDs.
§ Automobiles may use gold for heat dissipation.
§ Gold can be manufactured so thin that it appears transparent. It is used in some aircraft cockpit windows for de-icing or anti-icing by passing electricity through it. The heat produced by the resistance of the gold is enough to deter ice from forming.