Radiolarite (Jurassic) from the Alps.

Radiolarite is a siliceous, comparatively hard, fine-grained, chert-like, and homogeneous sedimentary rock that is composed predominantly of the microscopic remains of radiolarians. This term is also used for indurated radiolarian oozes and sometimes as a synonym of radiolarian earth. However, radiolarian earth is typically regraded by Earth scientists to be the unconsolidated equivalent of a radiolarite. A radiolarian chert is well-bedded, microcrystalline radiolarite that has a well-developed siliceous cement or groundmass.[1]

The Windalia radiolarite is a Cretaceous formation in Western Australia. The formation contains abundant foraminifera, radiolaria and calcareous nanoplankton fossils.[2] Locally the varicolored opaline to chalcedonic radiolarite is mined and used as an ornamental stone termed mookaite.[3]


  1. ^ Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, J.A., eds. (2005) Glossary of Geology (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. ISBN 0-922152-76-4
  2. ^ D. W. Haig, et. al., Mid-Cretaceous calcareous and siliceous microfossils from the basal Gearle Siltstone, Giralia Anticline, Southern Carnarvon Basin, Alcheringa: An Australasian Journal of Palaeontology, Volume 20, Issue 1, 1996, pages 41‑68
  3. ^ Mookaite at

External links