How the Mohs Scale Works


If you have a mineral specimen of unknown hardness, and reference mineral #5 can scratch it, then the hardness of your specimen is less than or equal to a Mohs hardness of 5. Similarly, if your specimen cannot be scratched by reference mineral #5, then its hardness is greater than or equal to a Mohs hardness of 5.

By doing successive tests with different reference specimens, you can closely estimate the Mohs hardness of your mineral specimen.

The Mohs hardness of a mineral is important information for determining the identity of your specimen.

Mohs hardness test
Mohs hardness test: When conducting the test, place the unknown specimen on a table top and firmly hold it in place with one hand. Then place a point of the reference specimen against a flat, unmarked surface of the unknown specimen. Press the reference specimen firmly against the unknown, and deliberately drag it across the flat surface while pressing firmly. To avoid injury, drag the known specimen away from your body and parallel to the fingers that are holding the unknown specimen.

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