{"thcode":4,"term":{"code":"2.6","name":"Chemical sedimentary rock","parent":"2","scope":"A sedimentary rock composed primarily of material formed directly by precipitation from solution or colloidal suspension or by the deposition of insoluble precipitates."},"uf":[],"bt":[{"code":"2","name":"Sedimentary rock","parent":"0","scope":"A rock resulting from the consolidation of loose sediment that has accumulated in layers..."},{"code":"0","name":"Earth material","parent":null,"scope":"Geologic map unit classification (Bruce R. Johnson) version 6.2: A hierarchical classification of earth materials for digital geologic maps."}],"nt":[{"code":"2.6.2","name":"Chert","parent":"2.6","scope":"A hard, extremely dense or compact, dull to semivitreous, microcrystalline or cryptocrystalline sedimentary rock, consisting dominantly of interlocking crystals of quartz less than 30 \u00c2\u00b5m in diameter..."},{"code":"2.6.1","name":"Evaporite","parent":"2.6","scope":"A nonclastic sedimentary rock composed primarily of minerals produced from a saline solution as a result of extensive or total evaporation of the solvent."},{"code":"2.6.5","name":"Exhalite","parent":"2.6","scope":"A chemical sedimentary rock, usually containing oxide, carbonate, or sulfide as anions, and iron, magnesium, base metals, and gold as cations, formed by the issuance of volcanically derived fluids onto the sea floor or into the sea."},{"code":"2.6.4","name":"Iron formation","parent":"2.6","scope":"A chemical sedimentary rock, typically thin-bedded and\/or finely laminated, containing at least 15% iron of sedimentary origin, and commonly but not necessarily containing layers of chert"},{"code":"2.6.3","name":"Novaculite","parent":"2.6","scope":"A dense, hard, even-textured, light-colored, cryptocrystalline siliceous sedimentary rock, similar to chert but characterized by dominance of microcrystalline quartz over chalcedony."}],"rt":[]}