Chromite is the most important ore of chromium from which it derives its name. Chromium is an important metal and has a wide range of industrial uses.
Chromite forms in deep ultra-mafic magmas and is one of the first minerals to crystallize. It is because of this fact that Chromite is found in some concentrated ore bodies. While the magma is slowly cooling inside the Earth's crust, Chromite crystals are forming and because of their density, fall to the bottom and are concentrated there.
Although its primary origin is ultra-mafic rocks such as peridotites, Chromite is also found in metamorphic rocks such as serpentites. Chromite, as is indicated by its early crystallization is resistant to the altering affects of high temperatures and pressures. Thus it is capable of going through the metamorphic processes unscathed, while other minerals around it are being altered to serpentine, biotite andgarnets. This characteristic also explains chromites use as a refractory component in the bricks and linings of blast furnaces.
Usually magnesium is present in Chromite substituting for the iron and in fact a solid solution series exists between Chromite and the much rarer mineral magnesiochromite. All Chromite specimens in nature contain some magnesium, likewise all natural magnesiochromites contain some iron. Magnesiochromite is grayer in color and in streak and has a slightly lower density than Chromite at a specific gravity of 4.2 to 4.4.