Types of Precious Metals

As with most rocks and minerals, what makes one valuable is its rarity combined with desirability. All metals are minerals. Some are rarer and some are more beautiful than others. Among the precious minerals traded at precious metal exchanges the most recognized are gold, silver, platinum and palladium. However, copper and mercury can also be found there.
Historically, precious metals became the basics for a monetary standard. Rare metals were (and still are) used in art, jewelry and in minting coins. Today, rare metals are also used in electronics and other scientific fields.

Gold

Gold can be found in South Africa, the Alaskan Yukon, California, the Northwest Territory of Canada and in many of the former Soviet states. Gold is considered rare and occurs in shapeless grains, sheets and flakes most commonly. It is a fairly soft metal, heavy and malleable. It is an excellent conductor of heat and electricity and is insoluble in acid--except when exposed to aqua regia. Gold has long been prized as a monetary standard, but has also had uses in dentistry and for electronic and scientific instruments.

Silver

Silver comes from Norway, Mexico, Chile, Ontario), Australia and Colorado. The largest blocks of silver come from Aspen, Colorado, but the greatest quantity is mined from the Guanajuato mine in Mexico. Silver can also be found in the island of Sardinia. The mineral is fairly soft, heavy and malleable and often takes on a wire-like appearance snaking over another mineral. It is soluble in nitric acid and is the best-known conductor of heat and electricity. Silver is used in jewelry, chemistry and electronics. It is also used in film photography. The United States, and other countries, still use silver (generally in an alloy) for currency.

Platinum

Platinum is found in rivers running down the Urals. Deposits are also found in Canada, South Africa, Colombia, Peru and the United States. The mineral is medium hard and extremely heavy, yet malleable. It is insoluble in acids, except for aqua regia. It is a good conductor of heat and electricity, which makes it valuable in engineering. Platinum can be slightly magnetic if small iron impurities are present. Besides being used in jewelry, platinum is used in making precision instruments and laboratory equipment. It also serves as a catalyst.

Palladium

Palladium is mined in South Africa, Russia, Ontario and Montana. It is a member of the platinum group of metals. Of the platinum group, palladium has the lowest melting point and is the least dense. It is a soft metal that dissolves in nitric, sulfuric and hydrochloric acid. It is used in jewelry, electronics, dentistry, medicine, chemical applications and groundwater treatment. Yet more than half the palladium mined is used in catalytic converters.

Copper and Mercury

Copper, as a metal, is second only to iron in importance in human history. Although copper is still used for jewelry (some with reputed healing properties), its main use is in electrical engineering and in creating alloys--such as brass and bronze. Copper is an excellent conductor of heat and electricity and dissolves easily in nitric acid.
Mercury is the only mineral to be in a liquid state at normal temperatures. It is an excellent conductor of heat and electricity. It is used in amalgams for extracting gold and silver. It further has uses in manufacturing explosives, in electrical engineering, in physics equipment, and in pharmaceutical and medical proposes.