MSI’s Nile Grey River Rock with approximately. 40 lbs. bag contains grey quartz river rock that lends a fine decorative touch to various installs. Ideal for use as an addition to your landscape, these decorative rocks protect the soil from temperature extremes, restrain the growth of weeds and also lend a natural look to your garden. The river rock is ideal for use near areas that are prone to washouts like under downspouts and may be used at front entrances to add a professional look. Note: Rocks are a natural material and are therefore subject to changes in color and texture over time. Irregularities and consistency of color in each bag should not be considered a fault but the inherent beauty of the natural stone.