One of the mysteries of the English language finally explained.
A hard, dark, opaque rock composed of silica (chalcedony) with an amorphous or microscopically fine-grained texture. It occurs as nodules (flint) or, less often, in massive beds.
- ‘The deposits immediately above the maximum flooding surface are thinly interbedded ammonoid-bearing cherts and lime mudstones.’
- ‘Crystals of brown sphalerite are found in fractures and on the surfaces of some chert nodules.’
- ‘It comprises turbiditic elastic rocks with cherts, pillow lavas and greenstones.’
- ‘The sedimentary lenses are composed of limestone, sandstone, siltstone, mudstone, shale, chert and well-bedded calci-turbidite.’
- ‘In fact, seventeen of the fifty-seven sites are specifically listed for agate, chalcedony, chert, jasper, or petrified wood.’
- ‘The volcano-sedimentary sequence is characterized by lava flows alternating with grey shales and occasional red chert bands.’
Late 17th century (originally dialect): of unknown origin.
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