A new kaolin deposit in western Africa: mineralogical and compositional features of kaolinite from Caluquembe (Angola)
Large kaolin deposits developed by weathering on Precambrian granitic rocks have been discovered in the Caluquembe area, Huíla province, Angola. To determine accuracy of analysis and to evaluate the samples kaolinite grade, it was used full profile Rietveld refinement by X-‐Ray Powder Diffraction (...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2019 |
| País: | España |
| Institución: | Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya) |
| Repositorio: | Recercat. Dipósit de la Recerca de Catalunya |
| OAI Identifier: | oai:recercat.cat:2072/358307 |
| Acceso en línea: | http://hdl.handle.net/2072/358307 https://doi.org/10.1007/s42860-019-00021-4 |
| Access Level: | acceso abierto |
| Palabra clave: | Caolí Terres rares Angola 549 |
| Sumario: | Large kaolin deposits developed by weathering on Precambrian granitic rocks have been discovered in the Caluquembe area, Huíla province, Angola. To determine accuracy of analysis and to evaluate the samples kaolinite grade, it was used full profile Rietveld refinement by X-‐Ray Powder Diffraction (XRPD) and Gravimetric Thermal Analysis (TGA). Caluquembe kaolin is mainly comprised of kaolinite (44 to 93 wt.%), quartz (0 to 23 wt.%) and feldspar (4 to 14 wt. %). AGFI Crystallinity Index, calculated by XRPD profile refinement, indicates low and medium defect kaolinite. Kaolinite particles show a platy habit and they are stacked together forming ‘booklets’ or radial aggregates, also occurring as fine anhedral particles in a finer-‐grained mass. Muscovite-‐kaolinite intergrowths have also been found. Whole-‐rock chemical composition was analyzed, including major, trace, and Rare Earth Elements (REE). Chondrite and Upper Continental Crust normalized REE patterns show the same tendency for all samples, with a significant enrichment in Light Rare Earth Elements (LREE). Mineralogical and compositional features of the Caluquembe kaolin indicate that it is a suitable material in the manufacture of structural products, such as bricks, pavers and roofing tiles. In addition, REE significant contents of the Caluquembe kaolin can be considered as a potential future target of mining exploration. Caluquembe; Angola; kaolinite; AGFI; REE. |
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