Weathered, circular carbonatite complex, consisting of three separate deposits hosted in beforsite, glimmerite, sövite, and some pyroxenite. With a diameter of 4.5 km, the Barreiro complex is the world's largest niobium deposit. Ore reserves were estimated in the early 1980s at more than 450 million tonnes of Nb ore (2.5% Nb2O5, 4.4% REO), and about 0.8 million tonnes of laterite ore (13.5% REO, 2% Nb2O5, 0.05% U3O8).
References:
- Nasraoui, M. and Waerenborgh, J.C. (2001): Fe speciation in weathered pyrochlore-group minerals from the Lueshe and Araxá (Barreiro) carbonatites by 57Fe Mössbauer spectroscopy. Canadian Mineralogist 39, 1073-1080.
- Orris, G.J., and Grauch, R.I. (2002): Rare earth element mines, deposits, and occurrences. USGS Open-File Report 02-189.
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Map Reference: 19°38'S , 46°56'W
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Mineral List:28 entries listed. 24 valid minerals.
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