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How to Test Specific Hardness

Specific hardness of a mineral is tested on the Mohs scale. Hardness measures the ability of a mineral to resist abrasion. The Mohs scale was developed by German mineralogist Friedrich Mohs.The Mohs scale standard is from one to ten, with one being the softest mineral, talc, and ten being the hardest mineral, diamond. The hardness test is made up of ten common elements: talc, gypsum, calcite, fluorite, apatite, orthoclase, quartz, topaz, corundum and diamond.

Things You'll Need

Mineral to be tested
Talc
Gypsum
Calcite
Fluorite
Apatite
Orthoclase
Quartz
Topaz
Corundum
Diamond

Instructions

- 1
  Number the minerals according to the Mohs scale, from one to ten starting with talc: talc (1), gypsum (2), calcite (3), fluorite (4), apatite (5), orthoclase (6), quartz (7), topaz (8), corundum (9), and diamond (10).
- 2
  Start with the softest mineral; scratch the talc with the mineral for which you are determining the hardness. If the mineral scratches the talc, it is harder.
- 3
  Scratch the gypsum with the mineral you are testing. If the mineral scratches the gypsum, it is harder than gypsum.
- 4
  Repeat the scratch test until you reach the element that your sample mineral does not scratch.
- 5
  Label your mineral with a number range, describing where it falls on the Mohs scale. The hardness range falls between the mineral the sample did not scratch and the highest level of mineral that was scratched. For example, if the mineral you are testing scratches elements up to fluorite but then does not scratch apatite, your element is between a 4 and a 5 on the hardness scale.

Rocks & Minerals