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GoldGold is a chemical element with the symbol Au and atomic number 79. The symbol Au is from the Latin aurum, which means 'shining dawn'. Gold is soft and shiny and is also one of the most malleable and ductile of the known metals. It is a good conductor of heat and electricity, and is not affected by air. Gold is a precious metal which, for many centuries, has been been prized for its beauty, resistance to chemical attack, and workability. Gold has an excellent chemical stability with a high resistance to corrosion and oxidation. In various countries, gold is used as a standard for monetary exchange, in coinage and in jewelry. A gold nugget is a naturally occurring piece of native gold. Gold mining consists of all processes of removing gold from the ground. Gold is now rarely found today as nuggets, but rather is extracted chemically from the ore by using a cyanide leaching process.
The purity of gold is measured in carats. Gold is usually alloyed with other metals (copper, zinc, nickel) to increase its hardness and durability. Pure gold is 24 carats. So, the higher the carat the purer the gold. The millesimal fineness is a system of denoting the purity of gold by parts per thousand of pure metal by mass in the alloy. The 24 carats gold has a fineness of 999. The 18 carats gold has a fineness of 750, meaning it contains 75% gold and 25% alloy. 12 carat gold contains 50% gold and so forth. |
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