Gold is a precious metal that has been used for centuries as a form of currency and in making jewelry. It occurs freely in nature and has a very distinctive appearance. Thus, it was one of the first metals discovered by man. Inscriptions that have been unearthed from ancient Egyptian sites show that gold was mined and refined before 4000 B.C. Just about every civilization has valued this metal.

Gold is the most malleable and ductile of all metals and it readily forms alloys with other metals. It is a good conductor for heat and electricity and is not affected by air, heat, moisture, oxygen and most corrosive agents. It is mainly yellow in color and other colors of gold, such as white gold, and rose gold, occur because of the alloys.

Gold is the main currency in the world and many nations maintain stockpiles of gold bullion to guarantee the value of their currency. Large quantities of this metal are used in making jewelry, ornaments and watches. Pure gold is too soft to use in its natural state, which is why it is always hardened with another metal, such as silver or copper and sometimes both. Gold-silver alloys are light in color, while gold-copper alloys have a reddish color. Gold is sometimes used for filling teeth and for other types of dental work. It is widely used in the manufacture of scientific apparatus and electronic devices, such as transistors.

Troy weight is used to measure gold and when it is alloyed with other metals, the term carat is used to tell how much gold is present. The price of gold is determined on the world market and due to its rarity it is costly. Humans have always searched for gold and many have become very rich because of it. Gold rushes have occurred throughout the world, especially in the US and Canada in the 19th century. South Africa is the world’s leading producer of this metal and has been since the 1880’s. Other major gold-producing countries are the US, Australia, China, Russia and Peru.