Abstract: A mobile rock collecting and crushing apparatus is disclosed which is specially adapted to be drawn behind and powered by a farm or garden tractor, for collecting rocks from fields, crushing them and expelling the crushed rock back to the field. The conventional power take-off shaft at the rear of the tractor turns a common drive shaft for reciprocating crushing blocks and for a rock collector and elevator. Provision is made for adjusting the fineness of the crushed rock expelled from the machine.