Abstract: A comminuting apparatus for reducing the size of particles, having a frame providing an internal perimeter and having a shape; a stone having a grinding surface for grinding a material and providing a perimeter having a shape corresponding to the shape of the perimeter of the frame and configured to be at least partially surrounded by the frame; wherein when the frame is rotated the perimeter of the frame is configured to coact with the perimeter of the stone such that the stone is rotated at substantially the same rate as the frame.