Abstract: An apparatus 10 for crushing materials such as rock, ore, coal, stone and the like includes two rolls 16A and 16B which are mounted in parallel to define a gap 18 therebetween. Chunks of material to be crushed are fed by a conveyor 12 into the nip 14 between the rolls. Each roll 16A and 16B is similar and includes longitudinally extending steps provided by outwardly extending faces and smoothly curved surface segments between the steps. When the rolls are counter-rotated at the same speed, the gap 18 is maintained substantially constant and effectively transversely reciprocates in location between limits defined by the outer extremity of the face of a step on one roll being located opposite the inner extremity of the face of a step on the opposite roll. Compared to smooth roll crushing the invention provides for greater reduction ratios to be achieved at slower rotational speeds and using smaller diameter rolls.