Corundum is a rock forming mineral. It is a crystalline form of Aluminum oxide. It is hard, very tough and a stable mineral second to Diamond. It contains minute amount of titanium, vanadium, Iron and chromium. It is a transparent mineral but may have other colours as a result of impurities present in it’s structure.
The two main gem varieties in Corundum are Ruby and Sapphire which are primarily the same properties but differs in colours. The name Corundum which is derived from the Tamil-Dravidian word “Kurundam” which means “ruby-saphire”.
It has a density of 4.02g/cm³ and hardness of 9.0 and mostly used as an Abrasive on Sandpaper and larger equipments. It occurs in beaches and streams as a detrital mineral due to its resistance to weathering. It can be seen in Igneous, metamorphic and sedimentary rocks.
Corundum may occur as accessory minerals in plutonic and volcanic rocks. Naturally, it often appears through metamorphism of Alumina rich rocks in moderate to high heat. It’s formation results from the hydrothermal fluid transformation of the constituents and mineralology of two rock sequence in contact.
There are Natural Corundum as well as synthetic Corundum. Both are utilized extensively in various industries as a result of their toughness, hardness and stability.
Corundum is used as an Abrasive due to its hardness. It can be crushed and modified to remove impure materials. They are used in different cutting applications. They are used widely in machineries like telescopes and space shuttle windows.
They are mined from deposits of gem gravel. They can be seen in Burma, India, Sri Lanka and Afghanistan. In recent years, some parts of Africa which includes Nigeria, Malawi and Kenya produces Corundum. It’s deposits can be found in Jos and Kaduna states in Nigeria.
The global market size of Corundum was at USD 2.6 billion in 2019 and anticipated to grow at a Compound annual growth of 4.0% from 2020-2027.