Radiolarite
“Built from microscopic glass skeletons”
Radiolarite is a siliceous sedimentary rock composed of the tiny glass-like skeletons of radiolarians — single-celled marine organisms. These intricate silica shells accumulated on deep ocean floors over millions of years, layer by layer, forming bands of red, green, and brown chert-like rock.
microcrystalline silica (opal/chalcedony), radiolarian tests, clay minerals, iron oxides
Alps (ribbon radiolarite), Franciscan Complex (California, USA), Japan, Oman, Greece
6-7
Individual radiolarian skeletons are so geometrically perfect and beautiful that Ernst Haeckel's 1904 illustrations of them became iconic works of scientific art that inspired Art Nouveau design.
Test Your Knowledge
How do radiolarian fossils in radiolarite help geologists reconstruct ancient ocean conditions?
Photo Attribution
Related Specimens
Want to identify rocks yourself?