Columbite–tantalite (Coltan) is the most important niobium (Nb)- and tantalum (Ta)-bearing economic mineral, commonly occurring in rare metal granite and pegmatite, alkaline granite, syenite and carbonatite. Its high U but low common Pb contents make it an ideal mineral for U–Pb isotopic dating of Nb–Ta mineralization. In order to ...
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Columbite-tantalite dating shows these rare earth pegmatite formed at 480–440 Ma, aligning with the post-orogenic event (Melcher et al., 2009). The Neoproterozoic Bupo-Kenticha rare metal pegmatites in southern Ethiopia also represent a globally significant source of Ta, with U–Pb dating of Mn-tantalite indicating ages of 530–529 Ma ...
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Figure 2 - Plots showing chemical contrasts between cassiterites from Pitinga min Bye a) Sn/10-Ti-Nb+Ta diagram; field I, field 2 and closed circles corresponc respectively to magmatic, hydrothermal and supergenic. cassiterites, b) Sn/10-Ti-Fe'" diagram showing the Fe "+ Ti enrichment trend of the NaEps cassiterite red zones (closed ...
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In this study, we focus on the metallogeny of the primary tin and columbite- tantalite mineralization in the northern part of the Kibara orogen (Rwanda, Burundi, Uganda, Tanzania, Maniema and …
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DOI: 10.1016/J.JAFREARSCI.2011.04.004 Corpus ID: 140170944; Late Neoproterozoic over of the cassiterite and columbite-tantalite bearing pegmatites of the Gatumba area, Rwanda (Central Africa)
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Since 2006, our working group has been investigating columbite-tantalite (coltan) mineralisation, especially in Africa, also within the wider framework of establishing certified trade chains. More ...
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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. The major part of the cassiterite mineralisation is, however, concentrated in zones associated with intense phyllic alteration.U-Pb ages of columbite-tantalite samples vary between ...
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Columbite forms a solid solution series with Tantalite known as the Columbite-Tantalite series. Columbite is the niobium-rich member, and Tantalite is the tantalum-rich member. Columbite is named after its niobium content, which was previous known as columbium prior to its renaming. Columbite is the most important mineral containing the rare ...
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Tantalite's greatest difference from columbite is its much higher specific gravity, 8.0+ compared to columbite's 5.2. Other properties that vary slightly are color, transparency and streak. Both minerals can be found more or less together in granitic pegmatites rich in lithium and phosphorus minerals with columbite concentrated at the edges of ...
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This is supported by studies showing that the sediments in catchments with lithium pegmatites contain the tin and tantalum ore minerals cassiterite and columbite-tantalite, respectively,...
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Compositional features differentiate the columbite-tantalite minerals and varieties of ixiolite. Cassiterite from W-Sn-bearing quartz veins is generally zoned; darker zones are commonly …
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The pegmatites of the Gatumba area (western Rwanda) have historically been mined for their columbite-tantalite and cassiterite mineralisation, but contain also beryl, apatite, …
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Mineralogy and chemistry of columbite-tantalite from Bugarura-Kuluti area, Karagwe-Ankole Belt, Rwanda: Indicators of pegmatite and granite evolution ... (Fe) inclusions in highly altered cassiterites. Wodginite contains distinctly increased content of Zr and Sn + Ti (Fig. 12 c-d) while CGM shows gradual increase in Sn + Ti with the increase of ...
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Unmixing bodies of tapiolite (F e, Mn)(Ta,Nb)2 O 6 occur in some deep -colored cassiterites or in some areas thereof. They can form extremely fine needles, oriented or not. In granites, cassiterite can unmix columbite or tantalite in the form of small rounded grains.
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Columbite-tantalite minerals commonly have a broad range of U contents that may reach several thousand ppm and may substitute for Fe and Mn into the crystal lattice, but for high U contents may form phases of its own (e.g., uraninite; cf. Romer et al., 1996). Furthermore, columbite-tantalite minerals typically have very low common Pb contents ...
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Columbite-tantalite-bearing granitoids of the Eastern Desert province of Egypt can be categorized into: (i) metaluminous alkali granites; (ii) peraluminous Li-albite granites; and (iii) metasomatized biotite and/or muscovite granite (i.e. apogranites). Columbite of the alkali granite is of FeNb 2 O 6 composition and associated with annite. The ...
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Columbite-group minerals (CGM: columbite-tantalite solid solution series) account for the majority of the current tantalum production in rare metal-endowed granitic pegmatite. Due to its high U and low common Pb, columbite-tantalite (termed coltan) is regarded to be useful for U–Pb dating ( Romer and Wright, 1992, Romer and Smeds, 1994 ...
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Cassiterites of different origins. ... Generally, Nb, Ta, and Ti are separated from the matrix of columbite-tantalite by acid hydrolysis or tannic acid precipi- tation. The separated fraction is ...
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The Central African Kibara orogen extends from the southeastern part of Uganda to the southern part of the Democratic Republic of Congo (DRC). It forms a met- allogenic province that hosts different types of granite-related mineralization: cassiterite, columbite-tantalite, wolframite, gold, monazite, amblygonite, beryl, etc. These minerals are present in different types of mineralization.
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Accessory minerals, including zircon, thorite, monazite, columbite-tantalite, cassiterite, bastnaesite, and xenotime are present in all phases of the Madeira igneous complex, indicating the ...
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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 ...
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Hydrothermal origin of columbite-tantalite is observed in greisens, expressed by a higher W concentration and coeval or even younger crystallization compared to the associated …
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with cassiterite and columbo-tantalite were widely . exploited. The veins have a preferred direction N25ºE to ... using U-Pb ages of columbite-tantalites and cassiterites, yielding ages of 301 ± ...
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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.
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Tantalite-columbite and tantalian rutile occur in cassitertie with exsolution texture and/or infiltrate into the micro-fissures of cassiterite with micro quartz vein. The compositions of tantalite …
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Columbite-tantalite crystals occur within quartz and albite, or are semi-enclosed by quartz and lepidolite in the late-stage mineralized granite without alteration (Fig. 2 D, E) and …
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Columbite-group minerals (CGM: columbite-tantalite solid solution series) account for the majority of the current tantalum production in rare metal-endowed granitic pegmatite. Due to its high U and low common Pb, columbite-tantalite (termed coltan) is regarded to be useful for U–Pb dating (Romer and Wright, 1992, Romer and Smeds, 1994, Romer ...
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Some Ta-Nb minerals, such as columbite-tantalite with a higher Ta content, appear to be also stable during the post-magmatic stage, in quartz-tourmaline+topaz greisen and higher-temperature quartz ...
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The cassiterites with non-metallic luster are in general light-colored and transmit light. The non-metallic luster can be described further and a distinction can be made between cassiterite with a greasy or adamantine luster. ... Columbite-tantalite, anatase and xenotime have been described as typical primary constituents of the cassiterite ...
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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. The major part …
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Columbite-tantalite ore mineralogy from the Kenticha rare-metal granites and pegmatites, Adola (Southern Ethiopia), has been studied in detail and the results can be used as an indicator of the metallogenic evolution. On the basis of the chemical data, the compositional fields of the columbite-tantalite collected from alaskitic granite, aplite ...
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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. The major part of the cassiterite ...
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