Topic
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 paper, the development of rates that quantitatively describe silicate mineral and rock weathering is discussed, and a summary of the available literature rate data for the weathering of several common silicate minerals is presented.
Abstract: This chapter presents (1) the development of rates that quantitatively describe silicate mineral and rock weathering, (2) a summary of the available literature rate data for the weathering of several common silicate minerals, and (3) a discussion of the chemical, physical, and hydrologic processes that control silicate mineral weathering at the Earth's surface. Quantitative rates of weathering are important in understanding reaction mechanisms and in addressing a number of economic and environmental issues. Mass change, defined in terms of elements, isotopes, or mineral abundances, is determined from either solid-state (soil, regolith, and rock) or solute (pore water, groundwater, and surface water) compositions. Solid-state mass differences reflect weathering over geologic timescales while solute compositions reflect the residence time of the water. These mass losses or gains are normalized to surface area defined on a geographic, volumetric, or mineral-specific basis. The advantages of this approach are that such rates are related to reaction mechanisms and can be used as predictive tools in estimating how weathering will behave under various environmental conditions.
145 citations
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TL;DR: The melting curve of forsterite, Mg2SiO4, has been determined at pressures up to 50 kb, using the single-stage apparatus and tungsten/75%tungsten-25% rhenium thermocouples.
Abstract: The melting curve of forsterite, Mg2SiO4, has been determined at pressures up to 50 kb, using the single-stage apparatus and tungsten/75% tungsten-25% rhenium thermocouples. The curve is linear within the precision of measurement; T = 4.77P + 1898, with P expressed in kilobars, T in degrees Celsius; S.D. = 11 deg. The temperature of melting of forsterite is not so dependent on pressure as that of other silicate minerals, which indicates that the eutectics of silicate systems that have Mg2SiO4 as a component should shift toward Mg2SiO4 with increasing pressure. Partial fusion would yield magmas poorer in silica at greater depths in the mantle.
145 citations
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TL;DR: In this article, the decomposition of silicate minerals and related substances by fungi has been investigated using two techniques: (a) the incorporation of the mineral material in agar medium, when its breakdown is indicated by the formation of clear zones round the fungal growth; (b) the determination of the metal and silicate ions, derived from the insoluble materials and brought into solution as a result of fungal activity in liquid medium.
Abstract: Summary
The decomposition of silicate minerals and related substances by fungi has been investigated using two techniques: (a) the incorporation of the mineral material in agar medium, when its breakdown is indicated by the formation of clear zones round the fungal growth; (b) the determination of the metal and silicate ions, derived from the insoluble materials and brought into solution as a result of fungal activity in liquid medium. Strains of fungi which produced citric and/or oxalic acid proved to be effective in decomposing certain natural silicates, while an oxalic acid-producing strain also released metallic ions and silica from rocks and soils. A possible role of fungi in biological weathering is discussed.
144 citations
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TL;DR: The structural environments of trace to minor levels (≈2000 ppm to ≈3.0 wt%) of U in several silicate glasses were examined as a function of oxygen fugacity, melt composition, and melt polymerization using X-ray (XANES and EXAFS) and optical absorption spectroscopies as discussed by the authors.
143 citations
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TL;DR: The 18O/16O ratios of coexisting silicate minerals in igneous and metamorphic rocks are approximately proportional to the following chemical index:Si+ 0.58Al equivalents/total cation equivalents.
142 citations