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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: Forsterite and enstatite were selected as important minerals present in igneous and mafic rocks Wollastonite, classified as a pyroxenoid, was chosen as a suitably fast-reacting proxy for examining silicate carbonation processes as discussed by the authors.
13 citations
TL;DR: In this article, a reactive transport model is used to evaluate whether the δ 44 Ca of modern hydrothermal fluids might have been higher during the Cretaceous and Late Cambrian, the ages of the Troodos, Oman, and Betts Cove ophiolites from which they have data.
13 citations
13 citations
TL;DR: In this article, the authors dealt with the general character of the heavy minerals of Indian beach placer sand deposits with special emphasis on the characters of ilmenite and found that these are mineralogically very complex.
Abstract: Indian beach placer sand deposits are, in general, ilmenite-rich. However, some concentrations are dominated by pyriboles. The Chavakkad-Ponnani (CP) area along the northern Kerala coast is one such deposit. This paper deals with the general character of the heavy minerals of CP with special emphasis on the characters of ilmenite. Most Indian beach sand ilmenites are of good quality. However, our observations on the ilmenites of CP using Optical Microscope, SEM and EPMA reveals that these are mineralogically very complex. The CP ilmenite varies from pure ilmenite to highly impure variety having intergrowths and inclusions of other oxide and silicate minerals. Ilmenite occurs as mixcrystals and forms intergrowth structure with hematite and Ti-hematite/ulvospinel; contains inclusions of hematite, quartz, and monazite. On the other hand ilmenite also occurs as inclusions within hematite and garnet. The pyriboles are dominantly amphiboles with hornblende-composition. Interestingly an inclusion of gold has been recorded within amphibole of hornblende composition. Garnets are mostly of almandine and pyrope type. Subordinate heavy minerals are sillimanite, zircon and rutile. Characteristic morphology, mineralogy and chemistry of amphibole, garnet and ilmenite together indicate that the placer sands of CP area are derived from the amphibolites, granite gneisses and basic igneous rocks lying in the hinterland towards the eastern border of Kerala. Though the overall quality of ilmenite is poor, highgrade ilmenite concentrate can be generated (of course with lower yield), by adopting precise mineral processing techniques. The CP deposit can be considered as a second-grade deposit but it has potential for future exploitation.
13 citations
TL;DR: In this paper, the authors report Mg and Li isotope data for water, river sediment, rock and mineral separates from the Leverett Glacier catchment, West Greenland, in order to assess whether the silicate mineral contributions to the dissolved load, previously determined using radiogenic Sr, Ca, Nd and Hf isotopes, are consistent with dissolved Mg, Li and Nd data, or whether a carbonate contribution is required as inferred previously for this region.
Abstract: Magnesium and lithium stable isotope ratios (dMg and dLi) have shown promise as tools to elucidate biogeochemical processes both at catchment scales and in deciphering global climate processes. Nevertheless the controls on riverine Mg and Li isotope ratios are often difficult to determine as a myriad of factors can cause fractionation from bulk rock values such as secondary mineral formation and preferential weathering of isotopically distinct mineral phases. Quantifying the relative contribution from carbonate and silicate minerals to the dissolved load of glaciated catchments is particularly crucial for determining the role of chemical weathering in modulating the carbon cycle over glacial-interglacial periods. In this study we report Mg and Li isotope data for water, river sediment, rock and mineral separates from the Leverett Glacier catchment, West Greenland. We assess whether the silicate mineral contributions to the dissolved load, previously determined using radiogenic Sr, Ca, Nd and Hf isotopes, are consistent with dissolved Mg and Li isotope data, or whether a carbonate contribution is required as inferred previously for this region. For dLi, the average dissolved river water value (+19.2±2.5‰, 2SD) was higher than bedrock, river sediment and mineral dLi values, implying a fractionation process. For dMg, the average dissolved river water value (-0.30±0.14‰, 2SD) was within error of bedrock and river sediment and within the range of mineral dMg values (-1.63 to +0.06‰). The river dMg values are consistent with the mixing of Mg derived from the same mineral phases previously identified from radiogenic isotope measurements as controlling the dissolved load chemistry. Glacier fed rivers previously measured in this region had dMg values approximately 0.80‰ lower than those measured in the Leverett River and could potentially be caused by a larger contribution from garnet (-1.63‰) dissolution compared to Leverett. This study highlights that dissolved Mg and Li isotope ratios in the Leverett River are affected by different processes (mixing and fractionation), and that since variations in silicate mineral dMg values exist, preferential weathering of individual silicate minerals in addition to carbonate should be considered when interpreting dissolved dMg values.
13 citations