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 regarded 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.