Corundum is a naturally occurring mineral made of aluminum oxide. It is known for its hardness, ranking just below diamond on the Mohs scale, which measures mineral hardness. Corundum can be found in various colors, including clear, red, blue, and yellow, depending on the presence of different impurities. The red variety is known as ruby, while the blue variety is called sapphire. This mineral is often used in jewelry due to its beauty and durability. Additionally, corundum is utilized in industrial applications, such as abrasives and cutting tools, because of its exceptional hardness. Its versatility makes it an important material in both decorative and practical uses.