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Surface exposure of pegmatite at the San Diego mine, Mesa Grande district, San Diego County, California (USA), inwhich large K-feldspar crystals that constitute an intermediate zone grewup fromthe ...
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This conclusion is also supported by the low Rb (458-533 ppm) and Cs (20.4-54.5 ppm) contents and the high K/Rb ratios (238-296) of K-feldspar from the Weiling pegmatite (Table 7) that differ ...
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Halo geochemistry reflects the internal evolution of the crystallizing pegmatite system, with residual fluid rich in incompatible elements accumulated by geochemical fractionation (Be, B, Cs, Sn, Ta) and by auto-metasomatic resorption of spodumene and K-feldspar (Li, Rb). The possibility of identifying rare-element enrichment trends by …
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Abstract. The New Exploration Tools for European Pegmatite Green-Tech Resources (GREENPEG) spectral database contains the spectral signature, obtained through reflectance spectroscopy studies, of European pegmatites and minerals as well as their host rocks. Samples include pegmatites of the Nb–Y–F (NYF) and Li–Cs–Ta (LCT) …
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This conclusion is also supported by the low Rb (458-533 ppm) and Cs (20.4-54.5 ppm) contents and the high K/Rb ratios (238-296) of K-feldspar from the Weiling pegmatite (Table 7) that differ ...
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The trace elements in K-feldspar are very useful geochemical indicators to assess not only the differentiation degree but also the potential for rare-metal …
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Fine-grained leucogranites are integrated with multiple pegmatoid varities and rare-metal–bearing (Be) pegmatites, including two-feldspar ones. The radiological age of rare-metal–bearing pegmatites is 139.6 Ma. (4) Young complex includes the units assumed to be generally called sodic and Na-Li pegmatites.
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Abstract. The geochemistry of K-feldspar for K, P, Sr, Ba, Rb, Cs, Ga, and of muscovite for the same elements plus Nb and Ta, was used for proving the parental …
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The K-feldspar from the two-mica granite generally has Rb < 837 ppm, Cs < 100 ppm, Tl < 5 ppm, and Ga < 18 ppm. Tourmaline muscovite granite, tourmaline albite granite, and K-feldspar from all types of pegmatite have Rb 460–4713 ppm, Cs 23–482 ppm, Tl 2–31 ppm, and Ga 15–51 ppm.
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The mineral chemistry of feldspar, including K-feldspar and plagioclase, is presented in Table 3. The composition plots in the feldspar ternary diagram are shown in Figure 4C . The K-feldspar in the Li-bearing pegmatites showed higher orthoclase contents (Or 97–98 ) than those of the granitic rocks (Or 91–93 ) ( Figure 4C ).
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According to the results reported above, rare metal-mineralized LCT type pegmatite is characterized by k-feldspar with high content of phosphorus, and thus, > 0.1 wt% P 2 O 5 in k-feldspar can act as a good indicator for prospecting LCT pegmatite …
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Atomic-absorption spectrophotometry, electron-microprobe and ion-microprobe techniques were used to analyze 33 samples of K-feldspar and 34 of …
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The PSs also contain a relatively better ordered K-feldspar and mark late magmatic phases (Panda et al. 1993). Thorianite occurs in a pegmatite near Bhaluchuan, which intrudes nepheline syenites and alkali syenites. The host pegmatite is zoned and contains feldspars, mica and quartz with minor amounts of heavy minerals (monazite, …
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Abundant reserves of Na-feldspar (albite) and K-feldspar (orthoclase or microcline) are found in granites, syenite, tracite and pegmatites. As both feldspar …
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Abstract. Temperatures of crystallization for all or portions of three thin granitic pegmatite dikes in southern California are derived from feldspar solvus …
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The standards were Amelia albite, anorthite from Pacaya volcano, K feldspar from the McDonald Mine pegmatite in Bancroft, ON, Canada, and adularia from St. Gotthard, Switzerland. The results of analyses of the standards using the two different techniques are within the uncertainty of each other (~ 0.5 wt. % difference where …
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In the pegmatite hosted by the quartz diorite (sample PgD), the modal abundance of plagioclase was 28 area%, quartz was 30 area%, and that of K-feldspar was 40 area%. Sample PgB has 15 area% plagioclase, 20 area% quartz, and 53 area% K-feldspar. Sample PgC has 37 area% plagioclase, 45 area% quartz, and 15 area% K …
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The K/Rb ratio in the more fractionated leucogranite is less than 50 and varies from 69.6 to 194 in the Ebrahim-Attar granitic pegmatites. This is consistent with less-evolved pegmatite. The most evolved pegmatite is located in the distal position to the parental granite, and the less-evolved pegmatite is in the proximal position.
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The trace elements in K-feldspar are very useful geochemical indicators to assess not only the differentiation degree but also the potential for rare-metal mineralization in pegmatite. The most key trace elements in K-feldspar are Li, Rb, Cs, Sr, Ba, and P (as P 2 O 5). Gordiyenko (1971) proposed that feldspars with high concentration of Li, Rb ...
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They are lowest in both quartz and K-feldspar from the pegmatite and increase up from volcanic to other igneous rocks of high temperatures. Fig. 9. Open in new tab Download slide. Correlations of Ti-Ti, Li-Li, and Ge-Ge between coexisting quartz and K-feldspar. Each data represent average concentrations for the whole sample except for …
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Pegmatites from southwestern Nigeria have mostly been characterized using mineralization with few reported studies using the fluid inclusion approach for pegmatite genesis. This study was carried out to determine the origin, type, and characteristics of fluid inclusions in pegmatites from the Oke-Ogun and Ibadan-Osogbo pegmatite fields of …
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The pegmatite comprises smoky quartz and feldspar with biotite, ... K-feldspar from Chaipaval, Bhoiseabhal and Sletteval was analysed for a number of trace elements, including Rb, Ba and Sr to determine: (1) how HGB pegmatites compare with economic, rare-metal pegmatites, and (2) to investigate the trace element variations …
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The Guangshigou deposit is the largest pegmatite-type uranium deposit in the Shangdan domain of the North Qinling Orogenic Belt, which is characterized by the enrichment of uraninite hosted in biotite granitic pegmatites. At Guangshigou, uraninite commonly occurs as mineral inclusions in quartz, K-feldspar and biotite or in interstices …
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An approximately 500 g piece of the pegmatite host unit of Albany K-feldspar was crushed using a high voltage pulse power SelFrag unit. Zircon and apatite were extracted from the crushed material through standard mineral separation procedures, including density separation using lithium metatungstate (LST) heavy liquid. ...
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Starting from the high-temperature crystallization of a pegmatite-forming melt, the first-formed alkali feldspar at the magmatic stage is sanidine, a disordered solid-solution with a composition close to (Na,K)AlSi 3 O 8 that incorporates other cations in the framework T and cavity M sites as "chemical impurities".
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The Li concentration of alkali feldspars, quartz, and muscovite from the spodumene-rich Main Sill of the Moblan pegmatite in Quebec, Canada, was used to evaluate the potential of the most common minerals in granitic pegmatites as indicators for the presence of Li-aluminosilicate mineralization. In Moblan, alkali feldspar crystals …
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Pegmatite is an intrusive igneous rock defined by its very large, interlocking crystals that can range in size from 1 cm to over 1 meter. It is usually primarily composed of quartz, feldspar, and mica, but often includes rarer minerals and gemstones. Pegmatite forms in the last stages of magma crystallization.
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The composition of K-feldspar from three types of pegmatite is presented in Table 2 (K-feldspar is absent from type-IV pegmatites). Systematic chemical varia-tions among the feldspars from the different zones into a pegmatite body are absent. Hence, we will only con-sider the variations among the different types of peg-matite. The orthoclase ...
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Plumbian K-feldspar also occurs in granitic pegmatite bodies formed by anatexis in the vicinity of a galena-bearing orebody (e.g., at Broken Hill, Australia); in this case, the resulting granitic ...
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ABSTRACT. The Cap de Creus pegmatite field exhibits a well-defined regional zonation of four types of granitic pegmatite: barren K- feldspar-rich pegmatites (type I), …
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