About 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 rock sand 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
Chemical Classification Oxide Color Dark gray to black, rarely brownish black Streak Dark brown Luster Metallic to sub metallic Diaphaneity Opaque Cleavage None Mohs Hardness 5.5 to 6S pecific Gravity 4.0 to 5.1 (variable) Diagnostic Properties Luster, streak Chemical Composition FeCr2O4 with magnesium substituting for iron in significant amounts Crystal System Isometric Uses An ore of chromium
Properties of Chromite
Chromite can be challenging to identify. Several properties must be considered to differentiate it from other metallic ores. Hand specimen identification of chromite requires a consideration of: color, specific gravity, luster, and a characteristic brown streak. The most important clue to identifying chromite is its association with ultrabasic igneous rocks and metamorphic rocks such as serpentine
Chromite is sometimes slightly magnetic. This can cause it to be confused with magnetite. Chromite and ilmenitehave very similar properties. Careful observations of hardness, streak, and specific gravity are required to distinguish these minerals in hand specimens
