Stone dust is the finest of the type of crushed stone. It is typically made out of crushed limestone, granite-gneiss, trap rock or a combination of those. It is commonly used as a binding agent with larger stone. Also, due to it’s strong, non-porous surface, stone dust is often used in between pavers and bricks in patios and walkways to keep grass and weeds at bay. Stone dust can also be used as a binding agent in cement mixtures.