What is the hardest mineral?

The hardest mineral on the Mohs scale of mineral hardness is diamond, with a hardness of 10. Diamond is composed of pure carbon and is known for its exceptional hardness and high thermal conductivity. It is also the third-hardest mineral on the Vickers scale and the second-hardest on the Brinell scale. Other minerals that are also considered very hard include moissanite and corundum (sapphire and ruby).