This sample of Phillipsite is displayed in the Smithsonian Museum of Natural History. Phillipsite is a silicate mineral of calcium, potassium and sodium. As an aluminum silicate, it is part of the zeolite group. The composition of this sample is listed as K(Ca0.5,Na)2(Si5Al3)O16.6H2O. Sometimes Phillipsite is indicated with suffix -K, -Ca, -Na, depending upon which ion is dominant. This specimen is about 16 cm wide and is from Richmond, Victoria, Australia.