sandstone
Sandstones are sedimentary rocks usually composed of quartz cemented with silica, iron oxide or calcium carbonate. Sandstones range from very soft and friable to very hard and durable, depending on the depth at which it was buried and the nature of the cement. Generally, the most durable sandstones are cemented with silica. Sandstone has a wide range of colors or textures. See quartz based stone. (Marble Institute, 2011)