The 1 1/2" to 2 1/2” Riverstone is the most common stone used in residential landscapes in Southwest Michigan. Riverstone is of higher quality than other readily available stone in our area. Riverstone, as the name would imply, is dredged from river basins. The movement of the river grinds down the stones until they are mostly round. The other desirable feature of Riverstone is that it contains relatively few brown clay stones. Brown clay stone is undesirable because it breaks apart after a couple of winters affecting the appearance of the stone mulch.