As a compression crusher, jaw crushers generally produce the coarsest material because they break the rock by the natural inherent lines of weakness. jaw crushers are an excellent primary crusher when used to prepare rock for subsequent processing stages. cone and gyratory.Buy manual / hand operated jaw crusher rock the crunch , geology assay frit jewelry in columbia, california, united states. this is a manually operated, cam driven, jaw type crusher which is operable with any 1/2 inch square drive bar; weight is 16lbs. the drive bar is not included. the useful jaw opening is 3” wide x 1 3/4.