Minerals — Ruby

Corundum is a mineral with the chemical formula Al2O3, and is one of the hardest minerals known, with a Mohs hardness of 9. This characteristic makes it highly valued for its use in abrasives and cutting tools.It is commonly found in metamorphic rocks such as schist and gneiss, as well as in igneous rocks such as syenite and nepheline syenite. It can also be found in alluvial deposits where it has been transported by water.Corundum is typically transparent or translucent, and can come in a range of colors including blue, pink, yellow, green, and black. The coloration is often due...