Columbite and Tantalite are the major sources of niobium and tantalum and their occurrences in rocks ... relationship between columbite and tantalite in cassiterites to help students of mineralogy ...Web
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Columbite-tantalite formed Karagwe–Ankole belt Kibara belt during the crystallisation of the pegmatites, followed by intense alkali metasomatism, i.e. widespread Gatumba area growth of albite and white mica. The …Web
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Disseminated cassiterites are enriched in Ta2O5 and Nb2O5 compared to vein cassiterites. Disseminated columbite-tantalites evolve toward Mn- and Ta-rich chemistries that contrast with the more Fe ...Web
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Columbite-tantalite formed during the crystallisation of the pegmatites, followed by intense alkali metasomatism, i.e. widespread growth of albite and white mica. …Web
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Spodumene occurs mainly in the shallow albite pegmatites (55–105 m depth), and disseminated beryl, columbite-tantalite, and cassiterite, mainly occur in pegmatites at depths less than 700 m. Eight samples were selected for monazite U-Pb geochronology and trace element geochemistry analyses from pegmatites and granites …Web
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Disregarding the randomly occurring Ta-Nb inclusions, such as listed in Table 4, we agree with HAAPALA ( 1977) who reported cassiterites from Eurajaki/Finland in which Ta, Nb and Fe are distributed "relatively homogenously". However, some of the Ta and Nb is present in discrete mineral phases, most probably tapiolite or columbite.Web
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Abbreviations: Clb = columbite; Ttl = tantalite. Cassiterite is locally intergrown with CGM along porous rim-1, which hosts uranmicrolite ((U,Ca) 2 (Ta,Nb) 2 …Web
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cassiterites with high common Pb, because the former is ... granite and in-situ columbite-tantalite U–Pb ages of the pegmatites (975 ± 8 Ma to 966 ± 9 Ma; Dewaele et al.Web
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The Dulong Sn-Zn-In polymetallic deposit in the Yunnan province, SW China, hosts a reserve of 5.0 Mt Zn, 0.4 Mt Sn, and 7 Kt In. It is one of the most important polymetallic tin ore districts in China. Granites at Dulong mining area include mainly the Laojunshan granite (third phase), which occurs as quartz porphyry or granite porphyry …Web
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Small production is recorded from placers in Guyana (Morabisi area; Fetherston, 2004;Kantharaja, 2011) and French Guiana, where 80-90 tonnes of alluvial columbite-tantalite have been produced from ...Web
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The age of apatite, cassiterite, columbite-tantalite (coltan) from five zones in Nanping No.31Li–Cs–Ta-rich type pegmatite deposit show remarkable two group ages (370–390 Ma and 145–160 Ma). ... According to the CL characteristics, cassiterites in Nanping No.31 pegmatite vein from five zones are divided into two groups, CASS-1 …Web
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Cassiterite and wolframite compositions from Sn > W- and W > Sn-bearing quartz veins in Northern and Central Portugal are compared to provide evidence on fluid compositions. In Sn > W-bearing quartz veins, euhedral cassiterite shows sequences of alternating parallel darker and lighter zones. The darker zones are pleochroic, oscillatory …Web
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Here, we report on new U–Pb age data from columbite-tantalite minerals and 40 Ar– 39 Ar age data on muscovite from the Gatumba area in Rwanda, forming part of the KAB (Fig. 2).The study area is situated in the western part of Rwanda, about 50 km west of Kigali and can be considered as representative of pegmatite mineralisation in the …Web
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Černý P, Ercit TS, Wise MA (1984) Compositional and structural variability in columbite-tantalite and tapiolite. Geol Soc Am Abstr Progr 16: 466 ... The 119 Sn Möss spectra, cell dimensions, and minor element contents of some cassiterites. Min Mag 40: 895–898. Google Scholar Cohen AJ, Adekeye JID, Hapke B, Partlow DP (1985 ...Web
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The chlorination of columbite-tantalite in the presence of a reducing carbon bed produces a mixture of volatile tantalum, niobium, iron, tin, aluminium and …Web
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The procedure can be applied for the determination of these elements in columbite/tantalite. The main advantage of the method is the ICP-OES determi- nation of Nb and Ta, and associ- ated elements ...Web
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Tantalite-(Mn) (MnTa 2 O 6) crystallizes at low temperature (<500 °C) whereas columbite-(Mn) (MnNb 2 O 6) has a lower solubility than tantalite-(Mn) (Linnen and Cuney 2005). The decrease of Nb/Ta observed at scales ranging from individual columbite-group crystals to zoning in pegmatite fields can be explained by fractional …Web
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Introduction. Tantalum (Ta) and niobium (Nb) are both key metals in high technology industrial processes. The most economically important Ta–Nb-containing minerals are those of the columbite–tantalite-group ((Fe,Mn)(Ta,Nb) 2 O 6) and wodginite (Mn(Sn,Ta)Ta 2 O 8).These minerals are found especially in granitic pegmatites or highly …Web
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On a procede a l'examen des donnees existantes sur la composition chimique et les proprietes structurales de columbite-tantalite, ferrotapiolite-manganotapiolite, ixiolite, wodginite, rutile tantalifere et niobifere, cassiterite niobo-tantalifere, et du groupe de pyrochlore. La comprehension de la cristallochimie de certaines de ces especes apparait …Web
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Columbite-tantalite, cassiterite and other Ta-Nb-Sn oxides in sediments from catchments that contain known LCT pegmatite occurrences show the same textural and chemical characteristics as …Web
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Columbite-(Fe) is a post-magmatic accessory mineral occurring within syenogranites and greisens from the Desemborque Pluton. The petrographic (SEM) and geochemical (EPMA and LA-ICPMS) examination of this mineral shows two distinct textural types within both the rocks, named columbite-1 and columbite-2. The columbite-1 type …Web
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Late Neoproterozoic over of the cassiterite and columbite-tantalite bearing pegmatites of the Gatumba area, Rwanda (Central Africa) J. Afr. Earth Sci. ... The exogranitic Rooiberg and Union Sn fields are identified by cassiterites with Zr/Hf of ∼40, whereas the endogranitic Zaaiplaats Sn field is characterised by cassiterites enriched ...Web
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The columbite-tantalite commonly exhibits a mottled or patchy zoned texture with the rims consistently higher in Ta than the cores, reflecting the later effect of a …Web
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Cassiterite is typically found in high-temperature hydrothermal veins and in granite pegmatites and greisens associated with granites, microgranites and quartz porphyries …Web
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Conflict minerals is a legally-defined set of minerals - columbite, tantalite, cassiterite, gold, wolframite or any of their derivatives - whose sale is being used to finance conflict in the Democratic Republic of Congo. Artisanal mining in Kailo, Congo. Your cellphone and computer probably contain metals from sources like this.Web
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New U–Pb dating CGMs (columbite-tantalite group minerals) in five zones have a consistent age (380 ± 10 Ma). Whilst U–Pb dating of apatite and cassiterite from different structural zones show remarkable two group …Web
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The tetragonal lattice structure enables cassiterites to incorporate dozens of elements within their crystal lattice (e.g., Fe, Ti, W, Zr, Hf, Ta, Nb, Mn, Sc, V and Sb). Thus, it is anticipated that variations of these elements should record information of potential elemental substitution mechanisms and precipitation environments of cassiterites.Web
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