Radiolarite consists mostly of remains of radiolarians. When the remains are well-cemented with silica, it is known as radiolarian chert. Many show evidence of a deep-water origin, but some appear to have formed in water as shallow as , perhaps in shelf seas where upwelling of nutrient-rich deep ocean water support high organic productivity. Radiolarians dominated the extraction of silica from seawater prior to the Jurassic.
Radiolarite consists mostly of remains of radiolarians When the remains are well-cemented with silica it is known as radiolarian chert Many show evidence of a deep-water origin but some appear to have formed in water as shallow as  perhaps in shelf seas where upwelling of nutrient-rich deep ocean water support high organic productivity Radiolarians dominated the extraction of silica from seawater prior to the Jurassic