Of difficulty

The test material should scratch with one mineral, and leave the line on the neighboring one, then its hardness indicator will lie between these two minerals of the scale. So, marble has a hardness of 3, lime — 1-3, granite — 6. The degree of difficulty of processing (teska, grinding), as well as the size of abrasion (floors, steps) depends on the hardness of the material. Abrasure is tested in special machines in the laboratory and measured by loss of volume after a certain number of revolutions of the machine, an abrasion of the sample.