The resistance of a substance of getting scratched is known as hardness. The test is done by positioning a sharp point of one specimen on an unmarked surface of another specimen and trying to generate a scratch. Thus, in the given case, quartz (having hardness 7) can be used to determine the hardness of another specimen in the following four ways:
1. If quartz can scratch sample B, then quartz is harder than sample B.
2. If quartz is not able to scratch sample B, then sample B is harder in comparison to quartz.
3. If quartz and sample B are equal in hardness, then they will not be able to produce a scratch on each other.
4. If quartz can be scratched by sample B, but it is not scratched by sample C, then in the case, the hardness of sample A comes in between the hardness of sample B and sample C.
The steps to perform the test are as follows:
1. Start by finding a smooth, unscratched surface for testing.
2. With one hand, hold the sample whose hardness is to be predicted against a tabletop so that the surface to be examined is accessible and exposed.
3. Hold the sample whose hardness is known in the other hand, and place a point of that sample against the selected flat surface of the unknown sample.
4. Strongly press the point of the known sample against the unknown sample, and strongly pull the point of the known sample across the unknown sample surface.
5. Examine the surface of the unknown surface, and not to get confused with a residue or mineral powder with a scratch. A scratch will be a distinguished groove cut on the surface of the mineral, it will not be a mark that vanishes away.
6. Perform the test a second time for the result to confirm.
