👉 Tourmalite is a mineral with the chemical formula Al2Si2O7. It is a yellow, white or grayish-white crystalline solid formed from the oxide of calcite (CaCO3). Tourmaline is named after the English mineral tourmaline, which was found in India and later on discovered in China. Tourmaline has a hardness of 6-8, making it one of the hardest known minerals. It is used as an abrasive, particularly in
