A coarse grained and generally igneous rock of even texture and light color, composed chiefly of quartz and feldspars. It usually contains small quantities of mica or hornblende, and sometimes minor accessory minerals. Depending on the feldspar present, granite may be pink, dark gray, or light gray. It is commonly believed to have solidified from molten rock (called magma) under pressure. However, some granite has no contact with surrounding wall rock, so it must have gradually degraded into metamorphic rock. Others show relic features found in sediments. This evidence suggests that some granite is not igneous in origin, but metamorphic. Some granite is the oldest known rock on earth. Crystallized at depth, granite masses are exposed at the earth’s surface by crustal movement or by the erosion of overlying rocks. 

River Rock is a natural rounded stone, with distinctive smoothness and colors. Centuries of moving glacial waters and shifting streambeds created this beautiful rock. Classic terrigenous sedimentary rocks consist of rock and mineral grains, or clasts, of varying size, ranging from clay-silt and sand up to pebbles and cobbles. These clasts were transported by gravity, mudflows, or running water, and eventually deposited in various settings in desert dunes, creek beds, streams and continental shelves. The term is also commonly used to describe paving stones, usually of granite composition. River Rock edging materials include ashlar and small building stones. 

Quartz sandstone is a metamorphic sandstone consisting of quartz grains cemented with silica. It is not as hard as quartzite. Geologically, it is an intermediate rock between sandstone and quartzite. (See quartzite and sandstone pages for those specific definitions.)