Corundum is a class of minerals, best known for the gem varieties such as ruby and sapphire, which are essentially the same mineral albeit of different colors. Corundum is a hard and highly stable mineral. It is the hardest mineral
Corundum is a class of minerals, best known for the gem varieties such as ruby and sapphire, which are essentially the same mineral albeit of different colors. Corundum is a hard and highly stable mineral. It is the hardest mineral