Abstract: Mookaite is an attractive varicoloured ornamental rock that is mined from small locales situated north of the Gascoyne River on the western margins of the Kennedy Ranges in Western Australia. Petrographically Mookaite comprises silicified radiolarite of the Windalia Radiolarite formation,part of the sedimentary sequences of the large Carnavon Basin. Subsequent to the formation of porcellanites by silicification,iron staining has resulted in the development of attractive yellow,red,purple and brown patterning.The porcellanite is fine-grained,hard and has no directional weaknesses;it takes an excellent polish and has worldwide popularity.