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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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Journal ArticleDOI
TL;DR: In this article, two composite broadband spectra (averages of 10 shots each) were calculated for each sample to produce two databases each containing the composite LIBS spectra for the same 52 mineral samples.

92 citations

Journal ArticleDOI
01 Apr 1991-Geology
TL;DR: In this paper, an investigation of silicate weathering in a Minnesota mire indicates that quartz and aluminosilicates rapidly dissolve in anoxic, organic-rich, neutral- pH environments.
Abstract: An investigation of silicate weathering in a Minnesota mire indicates that quartz and aluminosilicates rapidly dissolve in anoxic, organic-rich, neutral- pH environments. Vertical profiles of pH, dissolved silicon, and major cations were obtained at a raised bog and a spring fen and compared. Profiles of readily extractable silicon, diatom abundance, ash mineralogy, and silicate surface texture were determined from peat cores collected at each site. In the bog, normally a recharge mound, dissolved silicon increases with depth as pH increases, exceeding the background silicon concentration by a factor of two. Silicate grain surfaces, including quartz, are chemically etched at this location, despite being in contact with pore water at neutral pH with dissolved silicon well above the equilibrium solubility of quartz. The increasing silica concentrations at circum-neutral pH are consistent with a system where silicate solubility is influenced by silica-organic-acid complexes. Silica-organic-acid complexes therefore may be the cause of the almost complete absence of diatoms in decomposed peat and contribute to the formation of silica-depleted underclays commonly found beneath coal.

91 citations

Journal ArticleDOI
01 Dec 1996-Nature
TL;DR: In this paper, the authors report the complete structure determination of an inorganic crystalline silicate (CaSi2O5) containing SiO5 groups and confirm the previous attribution1,2,9 of peaks in the 29Si NMR spectrum of this material to the presence of pentacoordinate silicon.
Abstract: IN silicate minerals formed at pressures typical of the Earth's crust, the silicon is usually coordinated by four oxygen atoms. In contrast, silicates formed at higher pressures, typical of the Earth's transition zone and lower mantle, contain predominantly six-coordinated silicon. Silicon coordinated by five oxygen atoms is not normally found as a structural element in crystalline phases, but is nevertheless believed to play a central role in many dynamic processes that occur in silicates. For example, pentacoordinate silicon is probably a component of aluminosili-cate melts and glasses at mantle temperatures and pressures1,2, where it will dominate their transport properties3–6; it is also believe to act as an intermediate activated state during oxygen diffusion in silicate minerals7,8. Here we report the complete structure determination of an inorganic crystalline silicate—CaSi2O5—containing SiO5 groups. Our results confirm the previous attribution1,2,9 of peaks in the 29Si NMR spectrum of this material to the presence of pentacoordinate silicon, and the detailed geometry that we determine for the SiO5 group should provide a firm basis for characterizing and quantifying the role of pentacoordinate silicon in silicate melts and glasses.

91 citations

Journal ArticleDOI
TL;DR: In this paper, the authors compare the results of two different laboratories, using replicates of the same silicate samples, and show that coupled laser fluorination, dual-inlet IRMS procedures for oxygen three-isotope analysis of silicates, at high precision, gave reproducible accuracy for the slope value.

91 citations

Book ChapterDOI
01 Jan 1984
TL;DR: The most abundant element in the whole Earth (35 wt. %), but it represents only 5% of the mass, and less than 2% of atoms in the crust as mentioned in this paper.
Abstract: Silicate minerals are the commonest accessible materials on Earth. Thanks to the strong affinity of silicon for oxygen and the low density of the resulting oxides (3 g/cm3) compared with the average global density (5.5 g/cm3). Well over 90% of the crust is made up of silicates. Other elements are concentrated in the upper layers of the Earth when they form particularly stable simple oxides or complex oxides with Si02, and just eight elements together account for nearly 99% of the crustal mass. After oxygen and silicon itself come aluminum, iron, and four alkali or alkaline earth elements. Aluminosilicates are therefore the principal terrestrial minerals. Iron is believed from the evidence of meteoritic and stellar abundances, and the Earth’s density profile, to be the most abundant element in the whole Earth (35 wt. %), but it represents only 5% of the mass, and the less than 2% of the atoms in the crust. No other useful Mossbauer element is sufficiently plentiful for it to appear as a significant constituent of common natural minerals (e.g., Sn 2 ppm; Sb 0.2 ppm; Dy 3 ppm). The striking fact that 94% of the crust, by volume, is made of oxygen reflects the large ionic radius of O2−, 1.40 A, and the elementary principle of crystal chemistry that the structures of oxides, silicates included, are basically closely packed arrays of oxygen anions with small metallic cations in the interstices. Figure 1 summarizes the composition of the crust by mass, number of atoms, and volume, thereby situating in a global context the subject matter of this chapter—silicate minerals containing iron along with varying amounts of other major elements.

90 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202344
202264
202153
202064
201951
201865