| | Journal (article/letter/editorial) | xxxx Keywords: Carbonatites Niobium ore deposits Pyrochlore Laterite Supergene ores a b s t r a c t This...deposit is unique with respect to the varieties of pyrochlore present; extent of replacement by other minerals;...units of carbonatite contain distinct suites of pyrochlore. Bulk rock analysis for Nb gives no indication...and physical concentration of resistant primary pyrochlore. Intense lateritization results initially in...pyrochlores, and ultimately complete decomposition of pyrochlore and formation of Nb-bearing rutile, brookite | | | Journal (article/letter/editorial) | considered for potential coproduction of Ta and Nb. Pyrochlore (Nb–Ta), columbitetantalite (Nb–Ta), wodginite...Weathered crusts overlying carbonatite complexes in Brazil and one hard rock carbonatite deposit in Canada...Economically, significant deposits of Ta and Nb contain pyrochlore, columbite-tantalite, fersmite, loparite and...Tantalum . Rare-elements . Strategic metals . Pyrochlore . Columbite . Tantalite Introduction Tantalum...solution series) and microlite (Ta-rich pyrochlore; Table 2). Pyrochlore (Nb-rich variety) and columbite (Nb-rich | | Melgarejo, Joan C., Costanzo, Alessandra, Bambi, Aurora C.J.M., Gonçalves, Antonio O., Neto, Andrés B. (2012) Subsolidus processes as a key factor on the distribution of Nb species in plutonic carbonatites: The Tchivira case, Angola. Lithos, 152. 187-201 doi:10.1016/j.lithos.2012.06.024 | Journal (article/letter/editorial) | Available online 28 June 2012 Keywords: Carbonatite Pyrochlore Niobium Magmatic Hydrothermal Supergenic a b...Tchivira carbonatites contain several pyrochlore generations. Rare pyrochlore crystals, close to the fluorcalciopyrochlore...carbonates and fluorite are also common. Distinct pyrochlore compositions are characteristic for each altered...Pb-pyrochlores and Nb-rich rutile replace earlier pyrochlore generations and are present as inclusions in...hydrothermal minerals. Textural evidences indicate that pyrochlore and these minerals are produced by precipitation |
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