Mookaite (Radiolarite) Age: Cretaceous, Aptian (125 - 113 million years ago) Location: Carnarvon Shire, West Australia
Radiolarians are microscopic organism which make up a large proportion of the ocean's plankton. They have silicate skeletons. Over long periods of time these silicate structures accumulate to form sedimentary rocks called radiolarites. This rock has undergone weathering, chemical processes which act on exposed sections of a rock and change them. The weathered rock is a form of porcelainite and does indeed look like porcelain when broken. Analysis of the foraminifera preserved in the rock gives detailed information about the ecology and conditions of the carnarvon basin during the early cretaceous.