What kind of rock is corundum produced?
Aluminum oxide (Al2O3) mineral. Due to Mohs hardness of up to 9, mainly used as high-grade abrasives. The crystal belongs to the three party system, a dolioform six square column, some are needle or plate. Aggregates are massive or columnar. Usually white, gray, yellow and other colors. If a small amount of Cr3+ is red, a ruby is called;
If Ti4+ and Fe2+ containing a small amount of blue, a sapphire; containing six symmetrically distributed acicular rutile or other inclusions in some crystals, can produce six star awn, known as star ruby or sapphire stars, are precious stones. Corundum is vitreous luster with no cleavage, but cracks occur because of the presence of poly twin crystals that are often formed by the base or face of a face. Specific gravity 3.98. Of relatively low silicate igneous and metamorphic rocks and common in alluvial deposits. The U.S. state of North Carolina and Georgia, Russia's Ural mountains, South Africa as the main origin of the transvaal.