Sunday, May 3, 2009
Mookaite jasper, also known as mookite, mookalite, mookerite,
moakite, moukalite and moukaite. However, mookaite is considered the correct
spelling and is named after the local area it comes from, Mooka Creek in the
Kennedy Ranges near Gascoyne Junction which is about 100 miles inland from the
coastal town of Carnarvon in Western Australia.
Mookaite is found only in Australia and is actually a fossiliferous sedimentary rock & it is reasonably common to find cavities left by decomposed belemnite casts or in some rare cases, impressions of ammonites. (Windalia Radiolarite) Microscopic examination shows this rock consists of the remains of tiny organisms known as radiolaria that have an unusual skeletal structure of opaline silica. Billions of these little critters were deposited as sediment in the shallow areas of ancient sea beds. When the seas retreated, these sediments were cemented into solid rock by silica carried in groundwater. The type and degree of silicification varies from place to place, forming opalite, chert and chalcedony.