Clays and Clay Minerals

, Volume 67, Issue 3, pp 228–243 | Cite as

A New Kaolin Deposit in Western Africa: Mineralogical and Compositional Features of Kaolinite from Caluquembe (Angola)

  • Esperança Tauler
  • Jingyao XuEmail author
  • Marc Campeny
  • Sandra Amores
  • Joan Carles Melgarejo
  • Salvador Martinez
  • Antonio O. Gonçalves


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 kaolinite grade, a full-profile Rietveld refinement by X-ray Powder Diffraction (XRPD) and Thermal Gravimetric Analysis (TGA) was used. Caluquembe kaolin is composed mainly of kaolinite (44–93 wt.%), quartz (0–23 wt.%), and feldspar (4–14 wt.%). The Aparicio-Galán-Ferrell index (AGFI), calculated by XRPD profile refinement, indicates low- and medium-defect kaolinite. Kaolinite particles show a platy habit and they stack together forming ‘booklets’ or radial aggregates; they also occur as small anhedral particles in a finer-grained mass. Muscovite-kaolinite intergrowths have also been found. Whole-rock chemical analysis included major, trace, and Rare Earth Elements (REE). Chondrite-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 for the manufacture of structural products, such as bricks, paving stones, and roofing tiles. In addition, the significant REE contents of the Caluquembe kaolin can be considered as a potential future target of mining exploration.


AGFI Angola Caluquembe Kaolinite REE 



This research was supported by the CGL2012-36263, CGL2006-12973 and CGL2009-13758 projects of the Ministerio de Ciencia e Innovación of the Spanish Government, the AGAUR 2014SGR01661 project of the Generalitat de Catalunya and by a FI grant to J. Xu (coded FI_B 00904) sponsored by the Secretaria d’Universitats i Recerca of the Departament d’Economia i Coneixement of the Generalitat de Catalunya. The authors acknowledge the Scientific and Technical Centers of the University of Barcelona (CCiTUB) for their support in carrying out experimental analyses. Anonymous reviewers and the editorial staff, are thanked for helpful comments.


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Copyright information

© The Clay Minerals Society 2019
AE: Chun-Hui Zhou

Authors and Affiliations

  • Esperança Tauler
    • 1
  • Jingyao Xu
    • 1
    Email author
  • Marc Campeny
    • 1
    • 2
  • Sandra Amores
    • 1
  • Joan Carles Melgarejo
    • 1
  • Salvador Martinez
    • 1
  • Antonio O. Gonçalves
    • 3
  1. 1.Departament de Mineralogia, Petrologia i Geologia Aplicada, Facultat de Ciències de la TerraUniversitat de BarcelonaBarcelonaSpain
  2. 2.Departament de MineralogiaMuseu de Ciències Naturals de BarcelonaBarcelonaSpain
  3. 3.Departamento de GeologiaUniversidade Agostinho NetoLuandaAngola

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