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Clays and Clay Minerals
Published in Benny K.G. Theng, Clay Mineral Catalysis of Organic Reactions, 2018
The majority of chlorites have a trioctahedral layer structure, the particles being made up of successive 2:1 mica-type layers, which are interleaved with a continuous magnesium hydroxide sheet. The thickness of this interlayer sheet is ca. 0.4 nm, while that of the silicate layer is ca. 1.0 nm, giving a basal spacing close to 1.4 nm, which is a characteristic feature of the chlorite group of minerals (Figure 1.17). This value is comparable to the d(001) spacing of a two-sheet hydrate of Mg2+-vermiculite depicted in Figure 1.16b. Unlike vermiculite, however, the basal spacing of chlorite remains unchanged on treatment with ethylene glycol or heating up to 500°C.
The effect of mineral composition on direct aqueous carbonation of ultramafic mine waste rock for CO2 sequestration, a case study of Turnagain ultramafic complex in British Columbia, Canada
Published in International Journal of Mining, Reclamation and Environment, 2022
Jiajie Li, Anthony D. Jacobs, Michael Hitch
Minor phases identified by XRD included quartz (SiO2) (between 0.2 wt.% and 0.6 wt.%) and brucite (Mg(OH)2) (between 0.4 wt.% and 3.9 wt.%), which were present in all samples tested. Clinochlore ((Mg5Al)(AlSi3)O10(OH)8), a chlorite group member was found only in S14 and S16. This is likely an alteration product of the abundant ferromagnesian minerals present in the rocks. Troillite (FeS) was the only sulphide mineral abundant enough to be quantified with Rietveld refinement in any of the samples. Sjoegrenite (Mg6Fe3+2[(OH) 16CO3]·4H2O), a rare ferromagnesian hydroxide carbonate, was found only in 2 samples that also contained elevated diopside quantities. Both of these samples were logged as wehrlite (S2 and S7) with having less than 0.2 wt.% abundance. Sjoegrenite was not identified in the hand specimen. Its presence may be explained as an alteration product associated with the wehrlite rocks at Turnagain.
Manufactured Feldspar-quartz Sand for Glass Industry from Gneiss Quarry Rock Fines Using Dry Rare-earth Magnetic Separation
Published in Mineral Processing and Extractive Metallurgy Review, 2019
Luanna C. Moura, Flávio P. André, Hayla Miceli, Reiner Neumann, Luis Marcelo Tavares
Table 4 presents chemical analyzes results for the various samples from the tests. From an initial amount of 5.2% Fe2O3 in the feed, the various concentration stages (Figure 2) demonstrated to be able to reduce the Fe2O3 content to 0.23%. The sum of silica and alumina increased from less than 82% in the feed to above 90%, indicating mainly an enrichment in feldspars and quartz by magnetic separation. It is also evident in Table 4 that the Fe2O3 content reduced modestly in the first stage of separation, but significantly in the second stage, responsible for reaching a Fe2O3 content of 0.32% in the nonmagnetic product (cleaner concentrate). Table 4 demonstrates that several oxides, namely SiO2, Al2O3, K2O, and CaO, are shared between minerals that report to the nonmagnetic product, in particular feldspars and quartz, and those that report to the magnetic product, as mica and amphibole. On the other hand, some of the oxides in the sample are associated only to the magnetic waste. These are the cases of Fe2O3 and MgO that are primarily associated to mica-, amphibole-, and chlorite-group minerals, and TiO2, which is contained in amphiboles (Table 2). The product obtained after all stages of magnetic separation still contains nonliberated minerals, but using binocular magnifiers it became clear that the crystals recovered have more felsic than mafic minerals in volume (Figure 7(X)). Figure 7(X) also shows that the mafic minerals are recovered in the final product as inclusions in the particles containing primarily felsic minerals.
Vernacular Earthen Buildings from Leiria, Portugal – Material Characterization
Published in International Journal of Architectural Heritage, 2021
João Luís Parracha, José Lima, Maria Teresa Freire, Micael Ferreira, Paulina Faria
The results of XRD are summarized in Table 6. It can be observed that quartz, feldspar and muscovite are the predominant minerals both in the earthen materials from Pombal and Leiria. The mineralogical composition of the rammed earth samples is very similar; only kaolinite was not found in T3. Adobe samples slightly differ in terms of the presence of kaolinite and tosudite (a 1:1 regular interstratification of a chlorite group mineral and a smectite group mineral). Nevertheless, the differences between the mineralogical characterization of the rammed earth and adobe materials are not significant.