Chromite is an oxide mineral composed of chromium, iron, and oxygen. It is dark gray to black in color with a metallic to sub metallic luster and a high specific gravity. It occurs in basic and ultra basic 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.
|Physical Properties of Chromite|
|Color||Dark gray to black, rarely brownish black|
|Luster||Metallic to submetallic|
|Mohs Hardness||5.5 to 6|
|Specific Gravity||4.0 to 5.1 (variable)|
|Diagnostic Properties||Luster, streak|
|Chemical Composition||FeCr2O4 with magnesium substituting for iron in significant|
|Uses||An ore of chromium|
Uses of chrome ore
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 “nichroma” 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 an auto parts, appliances, and other products. These are given the name “chrome plated”. It is also used to make super alloys 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.
Worldwide, the leading use of gypsum is in the manufacture of cement and concrete, cement manufacture account around 60% of worldwide gypsum consumption…