Corundum

Corundum is a crystalline mineral with a hardness of 9 on the Mohs scale, second only to diamond. It appears in various colors depending on impurities, including red (ruby), blue (sapphire), and colorless (pure corundum). It forms in metamorphic and magmatic rocks, with significant deposits in Burma, Sri Lanka, and Thailand. Historically, rubies and sapphires (varieties of corundum) have been symbols of power and protection for kings and shamans.