chalcedonic chert

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chert — /tʃɜt/ (say chert) noun a hard, siliceous rock of opaline or chalcedonic silica, usually black or dull in colour, fracturing along flat planes, and occurring in bands or layers in sedimentary rocks, especially limestone …
chalcedony — chalcedonic /kal si don ik/, chalcedonous, adj. /kal sed n ee, kal seuh doh nee/, n., pl. chalcedonies. a microcrystalline, translucent variety of quartz, often milky or grayish. [1275 1325; ME calcedonie < LL chalcedonius (Vulgate, Rev. XIX, 19) … Universalium
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… … Wikipedia

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