Graphic granite

This 'graphic granite' is part of a pegmatite intrusion. It dispalys classic graphic intergrowth of quartz and alkali feldspar (orthoclase in this case). The feldspar component is crystallographically continuous across the specimen as evidenced by the consistent cleavage orientations. It is likely that all the quartz intergrowths also have the same crystallographic orientation. Such large grain sizes are common in pegmatites, which can have crystals that are several metres in scale. The quartz intergrowths also have a shape reminiscent of hieroglyphics. This common feature of 'graphic granite' has also earned it the name *runite*.