Orbicular granite (also known as orbicular rock or orbiculite) is an uncommon plutonic rock type which is usually granitic in composition. These rocks have a unique appearance due to orbicules - concentrically layered, spheroidal structures, probably formed through nucleation around a grain in a cooling magma chamber. So basically, some sort of crystal grain was rolled, twisted, twirled and turned in molten magma that resulted in concentrically spheroidal masses. The orbicules occur in a granodiorite matrix, and consist of andesine, plagioclase, hornblende, and biotite, arranged radially around a core of plagioclase and/or hornblende, or less commonly mafic schist. Make sense? And this material is carbon dated at around 2.7 BILLION years old. Crazy. How do you get your mind around that? This piece is one of the most striking forms of granite that we have the pleasure of working with in our stone art. It's found in very few places in the world and the location near Mount Magnet in Western Australia where this stone was found is the most renowned.