Corundum: Use as a Gemstone, Abrasive, Refractory
What is Corundum? Corundum is a rockforming mineral that is found in igneous, metamorphic, and sedimentary rocks. It is an aluminum oxide with a chemical composition of Al 2 O 3 and a hexagonal crystal structure.. The mineral is widely known for its extreme hardness and for the fact that it is sometimes found as beautiful transparent crystals in many different colors.