Saguaro is a colorful earthy blend of hand-picked fieldstone and natural quarried sandstone.  Both types of stone that comprise the Saguaro blend have the same composition and are separated only by the depth at which they are collected and quarried.  The fieldstones are hand collected from the fields; the pieces of stone have risen through the dirt over time and have been exposed to the elements.  The solid sandstone is beneath the dirt in the fields and is quarried below the surface.  In mining terms, this process is called removing the overburden to expose the bedrock.  The quarried stone has not been exposed to the elements so it has a different color and texture than the fieldstone.