: the quality or state of being hard
a : the cohesion of the particles on the surface of a mineral as determined by its capacity to scratch another or be itself scratched — compare mohs' scale
b : resistance of metal to indentation under a static load or to scratching
Examples of HARDNESS
- the hardness of a diamond
- The wood's hardness makes it suitable for carving.
First Known Use of HARDNESS
before 12th century
hardness noun (Concise Encyclopedia)
Resistance of a mineral to scratching, described relative to a standard scale of 10 minerals known as the Mohs hardness scale. Hardness is an important diagnostic property in mineral identification. There is a general link between hardness and chemical composition (via crystal structure); thus, most hydrous minerals, halides, carbonates, sulfates, and phosphates are relatively soft; most sulfides are relatively soft (two exceptions being marcasite and pyrite); and most anhydrous oxides and silicates are hard. See also hardening.
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