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Silicate minerals
About: Silicate minerals is a research topic. Over the lifetime, 1794 publications have been published within this topic receiving 67064 citations.
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TL;DR: In this article, the authors studied the oxygen isotope fractionation between analcime and water to test the feasibility of using zeolites as low-temperature thermometers, showing that the exchange has little effect on grain morphology and does not involve recrystallization.
32 citations
TL;DR: In this article, the geothermal fluids in seven Japanese geothermal systems are tested for attainment of aqueous and gaseous equilibrium, and the results show that the (Mg2+)/(K+)2 activity ratio of high temperature geothermal fluid of Japan can be represented by the reaction involving Mg-chlorite and K-bearing silicate minerals, though at lower temperatures other reactions may be responsible.
Abstract: The geothermal fluids in seven Japanese geothermal systems are tested for attainment of aqueous and gaseous equilibrium. The pH of fluids in the geothermal reservoir is approximately buffered by the assemblage K-feldspar–K-mica–quartz. (Na+)/(K+) and (Na+)/√(Ca2+) activity ratios are thermodynamically approximated by reactions between albite and K-feldspar, and between albite and anorthite (or Ca-zeolites), respectively. The (Mg2+)/(K+)2 activity ratio of high temperature geothermal fluids of Japan can be, represented by the reaction involving Mg-chlorite and K-bearing silicate minerals, though at lower temperatures other reactions may be responsible. The geothermal fluids are also commonly saturated with respect to anhydrite and calcite. A small amount of steam loss in the reservoir does not significantly affect the aqueous composition of the fluids. The partial pressure of CO2 is controlled by the reaction involving calcite, K-bearing silicate minerals, and albite or Ca-zeolite in geothermal systems which are not affected by steam loss and dilution. Equilibrium between CH4, CO2 and H2 is attained at high temperatures but not maintained to lower temperatures in most Japanese geothermal systems. The H2/H2S ratio is probably equilibrated with Fe-bearing minerals. Gaseous compositions are very good indicators to identify processes in the geothermal reservoir, such as boiling and dilution. Lastly, the major aqueous composition and pH of Japanese neutral Na-Cl type geothermal fluid are predictable if two variables (e.g., temperature and one of the cation activities) are provided.
32 citations
TL;DR: In this article, the Gemini quaternary ammonium salt surfactant (butane- α, ω -bis(dimethyl dodeculammonium bromide), 12-4-12) and its corresponding conventional monomeric surfactants (dedecyl trimethyl ammonium Bromide, DTAB) were adopted to comparatively study the flotation behaviors of illite, pyrophyllite and kaolinite.
32 citations
26 Oct 2015
32 citations
TL;DR: In this paper, the authors compare the Raman spectra of the crystalline and liquid phases of the SiO4 and AlO4 tetrahedra in framework silicates and show that the major spectral changes are observed at the α-β transitions, near 540 and 970 K, especially at low frequencies where the modes, involving mainly intertetrahedral motion, merge to a single broad envelope.
Abstract: β-cristobalite (SiO2) and β-carnegieite (NaAlSiO4) have been investigated by Raman spectroscopy up to their melting points at 1999 and 1799 K, respectively. In both cases, the major spectral changes are observed at the α-β transitions, near 540 and 970 K, especially at low frequencies where the modes, involving mainly intertetrahedral motion, merge to a single, broad envelope. These observations and comparisons made between the Raman spectra of the crystalline and liquid phases are consistent with the rigid-unit model recently proposed for describing the dynamics of SiO4 and AlO4 tetrahedra in framework silicates. From a structural standpoint, an important consequence is that the atomic mobility associated with premelting sets in at the low temperatures of these transitions, not in the vicinity of the melting point as for other silicate minerals.
31 citations