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Geology & Earth Sciences vocabulary · Rocks & Minerals

Hardness

Meaning in geology & earth sciences, with examples

/ˈhɑːrdnəs/nounCommon term

In geology & earth sciences, hardness means: A mineral's resistance to being scratched, measured on the Mohs scale from 1 (talc) to 10 (diamond). It is one of the first tests used to identify minerals.

In Turkish: sertlik, Mohs sertliği

How it is used

In the lab, students scratch minerals with a fingernail (about 2.5), a copper coin (about 3) and a steel knife or glass (about 5.5). Quartz, at 7, scratches glass. Phrases: hardness test, a hardness of 7, harder than glass.

Example sentences

  1. Calcite has a hardness of 3, so a knife scratches it easily.

  2. Check the hardness before you decide whether it is quartz or calcite.

Common collocations

  • Mohs hardness scale
  • hardness test
  • a hardness of 7
  • relative hardness
  • mineralA naturally occurring, inorganic solid with a definite chemical composition and an ordered internal structure, such as quartz, calcite or feldspar.
  • quartzA hard, common mineral made of silicon dioxide (SiO2), usually clear, white or grey with a glassy lustre. It has a hardness of 7 and no cleavage.
  • cleavageThe tendency of a mineral to break along flat, smooth planes of weakness in its crystal structure. Mica splits into thin sheets because of its perfect cleavage.
  • crystalA solid in which the atoms are arranged in a regular, repeating pattern, which often gives it flat faces and a typical shape.

This word in other fields

The same English word can have a different meaning in another field:

More terms: Rocks & Minerals

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