Essay by Gate KeeperHigh School, 10th gradeA+, January 1996

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Chromium is a very hard, brittle, gray metal, which is sometimes

referred to as Siberian red lead. It does not rust easily and becomes shiny and

bright when it is polished. The shiny trim on our automobile bumpers and

door handles is usually electroplated chromium.

Most chromium comes from something called chromite which is

a mixture of chromium , iron, and oxygen. Chromite is a common rather

ordinary black mineral that no one really noticed until more recent times.

Nearly all the world's supply of chromite comes from Zimbabwe, Russia,

Turkey, South Africa, Cuba, and the Philippines. The United States imports

almost all its chromite.

Chromium is added to other metals to make them harder and

more resistant to chemicals. Small quantities mixed with steel make the metal

stainless. Stainless steel is used to make cutlery and kitchen equipment

because it does not rust easily and takes a mirror-like polish.

This steel

contains about 13 percent chromium and 0.3 percent carbon.

The hardness of steel can be increased by adding small

quantities of chromium to it. Chromium steel alloys (mixtures containing one

or more metals) are used to make armor plating for tanks and warships. They

are also used for ball bearings and the hard cutting edges of high-speed

machine tools.

Nickel is highly resistant to electric current and is often added to

chromium steels to make them easier to work. For example, stainless steel

sinks can be pressed out from flat sheets of steel that can contain 18 percent

chomium and 8 percent nickel.

When nickel is mixed with chromium, the resulting metal can

stand very high temperatures without corroding. For example, the heating

elements of toasters can be made from an alloy that is 80 percent nickel and

20 percent chromium. This metal operates at a temperature...