Boulders

Boulders are large stones you place by hand or with a machine, usually 12 inches or bigger measured across the shortest side. They come out of a quarry pretty much straight, with no crushing and no screening. Weight depends on the rock. Granite runs about 175 pounds per cubic foot, and limestone runs about 165.

Suppliers sort boulders into size classes, like 12 to 18 inches, 18 to 24 inches, 24 to 36 inches, and specimen stones 36 inches and up. You buy them by the ton or by the piece, not by the yard, because every rock is a different shape. A 12-inch boulder weighs around 100 pounds. A 24-inch one can push 700, so you'll want a driver who can set it where you need it.