A crusher reducing limestone of crushing strength 70 MN/m2 from 6 mm diameter average size to 0.1 mm diameter average size, requires 9 kW. The same machine is used to crush dolomite at the same output from 6 mm diameter average size to a product consisting of 20 percent with an average diameter of 0.25mm, 60 percent with an average diameter of 0.125 mm and a balance having an average diameter of 0.085mm.