100 treasures

Richard Williamson, Orbicular Granitoid
Richard Williamson, Orbicular Granitoid
Richard Williamson, Orbicular Granitoid
The large polished sphere of orbicular granitoid nestles in a large rough block of the same rock. The sphere rotates on a layer of water pumped from within its mounting that cascades into an ornamental pool around the sculpture. The dark, layered 'orbs' are made up largely of blackish hornblende (an iron-bearing silicate mineral) and creamy white feldspar (a sodium-calcium aluminium silicate) crystals, with smaller amounts of other minerals. Orbicular rocks require special circumstances for their formation. This magnificent igneous rock is more than 2.5 billion years old and was found near Mount Magnet in Western Australia. The sculpture was donated to the Edward de Courcy Clarke Earth Science Museum by Mark Creasy.
Caption: Jenny Bevan
Photo: Pier Leach