Detail of "14639-88-4"

Reference

Radiolarites and siliceous oceanic sediments: a comparison

Radiolarites and siliceous oceanic sediments: a comparison. Steinberg, M.; Desprairies, A.; Fogelgesang, J. F.; Martin, A.; Caron, D.; Blanchet, R. (Lab. Geochim. Roches Sedimentaires, Fac. Sci., Orsay, Fr.). Sedimentology, 24(4), 547-63 (French) 1977. CODEN: SEDIAT. DOCUMENT TYPE: Journal CA Section: 53 (Mineralogical and Geological Chemistry) The SiO2 in samples of Jurassic radiolarian cherts is quartz [14808-60-7] or chalcedony [14639-89-5]. Most of these rocks contain feldspar, hematite [1317-60-8], illite [12173-60-3] and/or chlorite [1318-59-8], and swelling clays. Kaolinite [1318-74-7] is present locally. Three radiolarian chert facies are identified by chem. compn.: (1) massive cherts, (2) pelitic radiolarites, and (3) ferruginous radiolarites. Some of radiolarite clay minerals are detrital; diagenesis of clay minerals is not a significant source of radiolarite SiO2. The SiO2 minerals ranging from opal [14639-88-4] to quartz, characterize nonradiolarian siliceous ocean sediments (Cretaceous Pacific Ocean cherts and Cenozoic diatomaceous oozes from the Sea of Japan). These oceanic sediments contain feldspars, and have a clay mineralogy and a bulk chem. very similar to those of the radiolarian sediments. The Sea of Japan diatom oozes show that deep seas and distant continents are not essential to siliceous oceanic sedimentation.

Opal, chalcedony and calcite in the Cerro Autana Cave (Am

Opal, chalcedony and calcite in the Cerro Autana Cave (Am. 11), Amazon Federal Territory, Venezuela. Urbani, Franco (Esc. Geol. Minas, Univ. Cent. Venezuela, Caracas, Venez.). Bol. Soc. Venez. Espeleol., 7(14), 129-45 (Spanish) 1976. CODEN: SVEBAU. DOCUMENT TYPE: Journal CA Section: 53 (Mineralogical and Geological Chemistry) In the Cerro Autana Cave located in the Precambrian quartzites of the Rotaima Group, samples of speleothems with stalactitic, stalagmitic and corralloidal shapes were collected and later studied by petrog., microscope x-ray diffraction, chem. analyses, and scanning electron microscope. Mineralogically, they are composed of opal [14639-88-4], chalcedony [14639-89-5], and calcite [13397-26-7] in alternate concentric bands. The hypothesis which best explains the origin of the speleothems is that of direct pptn. of opal and calcite from percolating alk. waters at ambient temp. The chem. components come from the breakdown of feldspars of an arkosic horizon. Chalcedony may have been formed by recrystn. of the opal.