Mohs scale of mineral hardness finding the hardest material that the given material can scratch, or the softest material that can scratch the given material. For example, if some material is scratched by apatite but not by fluorite, its hardness on the Mohs scale would fall between 4 and 5. "Scratching" a material for the purposes of the Mohs scale means creating non-elastic dislocations visible to the naked eye. Frequently, materials that are lower on the Mohs scale can create microscopic, non-elastic dislocations on materials that have a higher Mohs number. While these microscopic dislocations are permanent and sometimes detrimental to the harder material's structural
Roll hardness tester of the movement, the pawl spring releases the hammer mass. The impact spring contracts causing the hammer mass to strike against the plunger. This is the impact. The hammer mass then rebounds back to the body of the hammer and distance travelled is recorded on the scale. The rebound distance depends directly on the hardness of the roll under test: A softer roll will absorb more of the impact energy and the rebound distance will be less. A harder roll will reflect more of the impact energy and the rebound distance will increase. Roll hardness is one of the most