Orbicular Granite
This geologically interesting rock comes from near Mount Magnet in Western Australia. The orbicules occur in a granodiorite matrix. They consist of andesine, plagioclase, hornblende & biotite arranged radially around a core of plagioclase &/or hornblende or less commonly mafic schist.
Here is a link to a site with detailed geological information on the formation of the orbicular granite.....http://www.earthmuseum.segs.uwa.edu.au/__data/page/48931/orbicular_granitoids.pdf
A large museum piece that I shipped to Tucson
last year. A polished face on the front .The back retains the natural
rough exterior.
An 18" sphere of orbicular granite.