Chromite / Chrome Ore
The only ores of chromium are the minerals chromite and magnesiochromite. Most of the time, economic geology names chromite the whole chromite-magnesiochromite series: FeCr2O4, (Fe,Mg)Cr2O4, (Mg,Fe)Cr2O4 and MgCr2O4. The two main products of chromite refining are ferrochromium and metallic chromium; for those products the ore smelter process differs considerably. For the production of ferrochromium the chromite ore (FeCr2O4) is reduced with either aluminium or silicon in a aluminothermic reaction and for the production of pure chromium the iron has to be separated from the chromium in a two step roasting and leaching process.
Chromite is also used as a refractory material, because it has a high heat stability.
Mining / Chrome Ore
In 2002 14,600,000 metric tons of chromite were mined. The largest producers were South Africa (44%) India (18%), Kazakhstan (16%) Zimbabwe (5%), Finland (4%) Iran (4%) and Brazil (2%) with several other countries producing the rest of less than 10% of the world production.
In April 2010 the Government of Ontario announced that they would be opening up a large chromite deposit to development in the northern part of Ontario known as the Ring of Fire.
Australia has a single working chromite mine in the Pilbara region of Western Australia, near the Indigenous community of Jigalong. The mine produces high grade lump chromite in the region of 300,000 tonnes per year.
Olivine, enstatite, plagioclase, serpentine, magnetite, ilmenite, pyrrhotite,pentlandite, ulvospinel.
Physical characteristics of Chromite / Chrome Ore
|Color||Brownish black to a deep dark black.|
|Luster||Metallic to greasy.|
|Transparency||Crystals are opaque.|
|Crystal System||Isometric; 4/m bar 3 2/m|
|Crystal Habits||include octahedrons often with dodecahedral faces modifing the edges of the octahedron to the point of rounding the crystal. Well formed crystals are rare and chromite is usually found massive or granular.|
|Specific Gravity||4.5 - 4.8 (average for metallic minerals)|
|Other characteristics||Weakly magnetic and an octahedral parting is sometimes seen.|
|Associated Minerals||olivine, olivine sand, talc, serpentine, uvarovite, pyroxenes, biotite, magnetite and anorthite.|
|Notable Occurrences||Include several mines in North Carolina, Montana, Maryland, Oregon, Texas, California and Wyoming, USA also found in Turkey; South Africa; Philippines, Russia, Kazakhstan and Australia|
|Best Field Indicators||Crystal habit, streak, associations with ultra-basic minerals and parting.|
Source Wikipedia / EK-Company