Hardness

: For the mathematical concept of the difficulty of proving a conjecture, solving an equation, etc., see computational complexity theory.

Scratch hardness

In mineralogy, hardness commonly refers to a material's ability to penetrate softer materials. An object made of a hard material will scratch an object made of a softer material. Scratch hardness is usually measured on the Mohs scale of mineral hardness. Pure diamond is the hardest known natural mineral substance and will scratch any other material. Diamond is therefore used to cut other diamonds; in particular, higher-grade diamonds are used to cut lower-grade diamonds.

Related Topics:
Mineralogy - Mohs scale of mineral hardness - Diamond

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The hardest substance known today are aggregated carbon nanorods, which have a hardness 1.11 times diamond.

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Estimates from proposed molecular structure indicate the hardness of beta carbon nitride should also be greater than diamond (but less than ultrahard fullerite). This material has not yet been successfully synthesized.

Related Topics:
Beta carbon nitride - Ultrahard fullerite

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