Metal is a solid mineral that usually has a shiny surface and generally a good conductor of heat and electricity, and can be melted or fused, hammered into thin sheets, or drawn into wires. Many metals are quite hard, with high physical strength. When polished, metals tend to be good reflectors of light. Common metals include bronze, copper, and iron whereas metals used for making jewelry, such as gold, platinum, and silver are known as ‘Precious Metals’.
Alloy is a mixture containing two or more metallic elements or metallic and nonmetallic elements usually fused together or dissolving into each other when molten. For example, brass is an alloy of zinc and copper. Metals easily form alloys with other metals. The presence of even a small amount of another element in a metal severely affects its properties.
History of Metals
Metals are as old as human civilization and their history can be traced back to 6000 BC. Currently there are 86 known metals but before the 19th century only 24 of these metals had been discovered and, of these 24 metals, 12 were discovered in the 18th century. Therefore, from the discovery of the first metals, such as gold and copper, until the end of the 17th century, some 7700 years, and only 12 metals were known. Four of these metals, arsenic, antimony, zinc and bismuth, were discovered in the thirteenth and fourteenth centuries, while platinum was discovered in the 16th century.
The other seven metals, known as the Metals of Antiquity, were the metals upon which civilization was based. These seven metals were:
- Gold, discovered in approx. 6000 BC
- Copper, discovered in approx. 4200 BC
- Silver, discovered in approx. 4000 BC
- Lead, discovered in approx. 3500 BC
- Tin, discovered in approx. 1750 BC
- Iron, smelted, discovered in approx. 1500 BC
- Mercury, discovered in approx. 750 BC
These metals were known to the Mesopotamians, Egyptians, Greeks and the Romans. Out of these seven ancient metals, five can be found in their native states. These five metals are gold, silver, copper, iron (from meteors) and mercury.
A precious metal is a metal with rare metallic chemical element and due to that, high economic value. Precious metals are less reactive than most elements, have high luster, and have higher melting points than other metals.
Historically, precious metals were widely used in making jewelry, ornaments, idols, temples, currencies, and war equipments, but are now regarded mainly as jewelry, investment and industrial commodities. The following three metals are widely traded and considered as precious metals due to their rarity and beauty.