Chromite

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What is Chromite?
Chromite is an oxide mineral composed of chromium, iron, and oxygen (FeCr2O4). It is dark gray to black in color with a metallic to submetallic luster and a high specific gravity. It occurs in basic and ultrabasic igneous rocks and in the metamorphic and sedimentary rocks that are produced when chromite-bearing rocks are altered by heat or weathering.

Chromite is important because it is the only economic ore of chromium, an essential element for a wide variety of metal, chemical, and manufactured products. Many other minerals contain chromium, but none of them are found in deposits that can be economically mined to produce chromium.


Uses of Chromite and Chromium:
Chromium is a metal used to induce hardness, toughness, and chemical resistance in steel. The alloy produced is known as "stainless steel." When alloyed with iron and nickel, it produces an alloy known as "nichrome" which is resistant to high temperatures and used to make heating units, ovens, and other appliances. Thin coatings of chromium alloys are used as platings on auto parts, appliances, and other products. These are given the name "chrome plated." It is also used to make superalloys that can perform well in the hot, corrosive, and high-stress environment of jet engines.

Chromium's name comes from the Greek word "chroma" which means "color." Chromium is used as a pigment in paint. The familiar yellow lines painted down the center of highways and the yellow paint used on school buses are often "chrome yellow" - a color produced from chromium pigment. Chromium is an important pigment in many types of paint, ink, dye, and cosmetics. Trace amounts of chromium produce the color in many minerals and gemstones. The red color of ruby, the pink of some sapphires, and the green color of emerald are caused by tiny amounts of chromium.


Did You Know?   School buses and yellow lines on highways are often painted with "chrome yellow" paint. The "chrome" means chromium was used as an ingredient.