What is gold ?

Gold is a comparatively dense, shiny, yellow metal. As an element, gold is quite resistant to corrosion (by oxygen, but also many other chemicals). There are medical (dentistry), chemical and industrial applications of gold. However, aside these rather limited applications (for which, in fact, gold often can be substituted with other materials like copper, ceramics etc.) Symbol Au: A soft, yellow, corrosion-resistant element, the most malleable and ductile metal, occurring in veins and alluvial deposits and recovered by mining or by panning or sluicing. A good thermal and electrical conductor, gold is generally alloyed to increase its strength, and it is used as an international monetary standard, in jewelry, for decoration, and as a plated coating on a wide variety of electrical and mechanical components.  How much gold is there ? The amount of gold that has been found or dug out in human history is estimated at 120,000 to 140,000 metric tons (1 metric ton = 1000 kilogram). This amount of gold would fit into one massive cube with edges of a length of 19 meters (imagine a cubic 6-storey house made of massive gold). Around 20-25% (30,000 metric tons) of this gold is hoarded by central banks. The rest is privately owned jewelry (70,000-80,000 metric tons) and bullion (20,000 metric tons). In other words, most of the world's gold is in private hands. The amount of gold that is mined per year is comparatively stable at just above 2% of the worlds above ground gold (around 2,600 metric tons per year) Gold, recognizable by its yellowish cast, is one of the oldest metals used by humans. As far back as the Neolithic period, humans have collected gold from stream beds, and the actual mining of gold can be traced as far back as 3500 B.C., when early Egyptians (the Sumerian culture of Mesopotamia) used mined gold to craft elaborate jewelry, religious artifacts, and utensils such as goblets. Why is it expensive ?  It is well known that gold is comparatively expensive (e.g. when compared with the same amount of iron or copper). So, why (at least over the last couple of thousand years) has humanity perceived gold as one of the most expensive materials on the planet? The reasons are in fact very simple: gold is rare, gold cannot be created (synthesized under economic costs) and, as mentioned before, it is shiny and does not oxidize. The latter property made gold an ideal material for jewelry and other representative uses. The ever growing demand for jewelry and the rareness of gold hence determined its price. In return, the high price made gold an ideal store of wealth. One kilogram of gold would have the volume of a small bar of chocolate and could easily be stored under your pillow or on the ground of the fish pond in your garden (no packaging required).  Properties of Gold Has a melting point of 1945 degrees Fahrenheit (1063 degrees Celsius). When alloyed (chemically combined) with other base metals the melting temperature of the resulting alloy is changed. 18K yellow gold has a melting point of 1675 degrees Fahrenheit and 14K yellow gold has a melting point of about 1550 degrees Fahrenheit. Has a specific gravity of 19.33. It is relatively heavy compared to most metals, such as silver (SG 10.7) or iron (SG 7.8). A notable exception is platinum (SG 21.4). Is more malleable than any other metal and can be hammered into foil so thin that it is almost transparent. Has a unique ductility property allowing it to be drawn into wire so fine it can barely be seen. Is deep yellow in color. Its great reflectivity properties help keep its brightness and color from fading with time. Will not rust, tarnish or corrode. Gold jewelry recovered from ancient Egyptian tombs is in the same state as when placed there over 4000 years ago. Is softer than most other metals. On the Mohs scale of hardness (which is a measure of a gemstone or mineral’s resistance to scratching), gold has a hardness value of 2 to 2.5. Diamond has a value of 10. Pure gold may easily be scratched. Fortunately, gold becomes harder when alloyed with other base metals. Is relatively scarce and therefore expensive. It is estimated that only 125,000 tons of gold have been mined the world over since the beginning of time. Is able to bond with other base metals. This property gives rise to the many different colors available in modern gold alloys.  Why is it expensive ?   It is well known that gold is comparatively expensive (e.g. when compared with the same amount of iron or copper). So, why (at least over the last couple of thousand years) has humanity perceived gold as one of the most expensive materials on the planet? The reasons are in fact very simple: gold is rare, gold cannot be created (synthesized under economic costs) and, as mentioned before, it is shiny and does not oxidize. The latter property made gold an ideal material for jewelry and other representative uses. The ever growing demand for jewelry and the rareness of gold hence determined its price. In return, the high price made gold an ideal store of wealth. One kilogram of gold would have the volume of a small bar of chocolate and could easily be stored under your pillow or on the ground of the fish pond in your garden (no packaging required).