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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, absorption coefficients associated with atomic motions of species expected in astronomical environments are determined from infrared measurements of various hydrosilicates, hydrated magnesium oxide, and the Al-bearing chain silicate, sapphirine.
Abstract: Absorption coefficients associated with atomic motions of species expected in astronomical environments are determined from infrared measurements of various hydrosilicates, hydrated magnesium oxide, and the Al-bearing chain silicate, sapphirine. Band types measured include O‐H stretching modes near 3 μm, Si‐O stretching motions near 10 μm, Si‐O‐Si bends near 14 μm, O‐Si‐O bends near 20 μm, and translations of cations such as Mg and Ca near 50‐200 μm. We obtain data from films of varying thickness and use a ratioing method. First, bandstrengths of O‐H fundamentals were determined from spectra obtained from films of controlled thicknesses, generally 6 μm. The O‐H absorbance strength was then used to accurately determine thickness for a thinner film of each mineral (found to be <1 μm), thus providing bandstrengths of all other absorptions. Thin films were prepared such that the fundamental lattice modes showed intrinsic behaviour (i.e. band shapes were unchanged upon further thinning) and O‐H modes are well resolved above the spectral noise. Bandstrengths were found to depend weakly on structure and should be applicable to other silicate minerals, allowing estimation of elemental concentrations independent of knowing the speciation of dust in astronomical environments. Comparison with observational data of NGC 6302 suggests that lizardite and saponite could be present in addition to refractory minerals.
93 citations
TL;DR: In this article, a first experimental study was conducted to determine the equilibrium iron isotope fractionation between pyrrhotite and silicate melt at magmatic conditions, where experiments were performed in an internally heated gas pressure vessel at 500MPa and temperatures between 840 and 1000°C for 120-168h.
93 citations
92 citations
TL;DR: In this paper, the mechanism of enhanced reduction of Fe(III) in iron-rich 2:1 clay minerals under sulfate-reducing conditions was studied using Desulfovibrio spp. strain G-11 with or without amended sulfate.
92 citations
TL;DR: The pore diameters and pore wall thickness of mesoporous molecular sieves derived from a layered silicate (kanemite) were estimated by X-ray diffraction, physisorption, transmission electron micrographs, 29Si MAS NMR, and modeling and simulation.
Abstract: The pore diameters and pore wall thicknesses of the mesoporous molecular sieves FSM-16 derived from a layered silicate (kanemite) were estimated by X-ray diffraction, physisorption, transmission electron micrographs, 29Si MAS NMR, and modeling and simulation. The XRD simulation with a simple model of a hexagonal array of cylinders gave reasonable values coinciding with those obtained by TEM and nitrogen adsorption, with some corrections. As-synthesized FSM-16 material had pore walls 0.4 nm thick, corresponding to the slightly less wrinkled single SiO4 tetrahedral layer observed in the crystalline layered silicate minerals, and an apparent pore diameter of 4.2 nm. Surfactant-free FSM-16, formed by calcination and exchange for H+, had thicker pore walls of 0.8 and 0.9 nm corresponding to double SiO4 tetrahedral layers and pore diameters of 3.4 and 3.7 nm.
92 citations