Use the Mohs Hardness test to find the hardness of unknown minerals.
Testing surface hardness can be done by various methods. The easiest method for testing hardness is the Mohs Hardness test. The Mohs test, developed by Friedrich Mohs, measures the hardness of an unknown mineral by testing it against the hardness of known samples. The known samples used in the test are numbered from 1 to 10. Once the test is completed, you will be able to assign a hardness score to the unknown mineral.
Instructions
1. Clean the unknown mineral with a brush or a clean cloth. Clean enough of the mineral to be able to scratch the surface.
2. Scratch the surface of the unknown mineral firmly with one of the reference samples on the Mohs scale (see Resources). Start with a sample that is low on the scale.
3. Examine the scratch on the unknown sample. You may need to use a magnifying glass to see clearly. If the sample made a scratch, then scratch the mineral again with a sample that is lower on the scale. If it did not leave a scratch, repeat with a sample that is higher on the scale.
4. Continue the scratching process until you have determined the hardest Mohs reference sample that will not scratch the mineral. The unknown mineral will have a Mohs hardness number between the number of the sample that will not scratch the mineral and the next highest number.
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