Korundiin

Korundiin is a mineral composed of aluminum oxide, Al2O3. It is a naturally occurring crystalline form of aluminum oxide and is known for its extreme hardness, making it one of the hardest naturally occurring substances. In its purest form, corundum is colorless. However, impurities can give it a wide range of colors. Red corundum is known as ruby, and corundum of any other color is known as sapphire. Both ruby and sapphire are highly valued gemstones.

Corundum crystallizes in the trigonal crystal system. It is typically found in metamorphic rocks such as marble, gneiss, and schist, as well as in some igneous rocks. It can also occur as detrital grains in sedimentary rocks. Due to its hardness and durability, corundum is also found in placer deposits. Notable occurrences include Myanmar, Sri Lanka, Madagascar, and East Africa.

Beyond its use as a gemstone, corundum has significant industrial applications. Its hardness makes it an excellent abrasive material, used in sandpaper, grinding wheels, and polishing compounds. It is also employed in the manufacturing of specialized lenses, watch crystals, and high-strength ceramic components due to its chemical inertness and high melting point. Synthetic corundum is produced industrially for many of these purposes.