As a subject matter expert in materials science, I can tell you that the hardest known form of carbon is diamond. Diamond is an allotrope of carbon where the atoms are arranged in a crystal lattice structure that is extremely tight and strong. This arrangement gives diamonds their remarkable hardness, which is rated as 10 on the Mohs scale of mineral hardness. Diamond's hardness is so significant that it is used in various industrial applications, such as cutting, drilling, and grinding tools.

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Diamond is currently thought to be the hardest natural material on Earth, having a hardness of ten out of ten on the Mohs scale of mineral hardness. Diamond is made up of carbon atoms which share strong covalent bonds (where electrons are shared between atoms) and are equally spaced in a lattice arrangement.read more >>