Corundum is a rock-forming mineral that has industrial applications, and it is used in electronics and jewelry. Corundum is the mineral name for gemstones commonly known as rubies and sapphires. A corundum with a red hue is known as a ruby, while a blue-colored corundum is called a sapphire.
Corundum is extremely hard, and it can be used to scratch and cut other minerals and gemstones. It is also used as an abrasive, and its powder and granules are used for polishing and grinding. In addition, it is used to make sandpaper and is a major component of emery stone. Corundum is used as a jewel bearing in watches, in ruby lasers and to make scratch-resistant windows in electronic devices. Due to its heat resistant properties, it is also used to make firebricks and kiln furniture.