RT Journal Article
T1 Crystallochemical characterization of the palygorskite and sepiolite from the Allou Kagne deposit, Senegal
A1 García Romero, Emilia
A1 Súarez Barrios, Mercedes
A1 Santarén Rome, Julio
A1 Álvarez Berenguer, Antonio
AB The Allou Kagne (Senegal) deposit consists of different proportions of palygorskite andsepiolite, and these are associated with small quantities of quartz and X-ray amorphous silica as impurities.No pure palygorskite or sepiolite has been recognized by X-ray diffraction. Textural and microtexturalfeatures indicate that fibrous clay minerals of the Allou Kagne deposit were formed by direct precipitationfrom solution. Crystal-chemistry data obtained by analytical/transmission electron microscopy (AEM/TEM) analyses of isolated fibers show that the chemical composition of the particles varies over a widerange, from a composition corresponding to palygorskite to a composition intermediate between that ofsepiolite and palygorskite, but particles with a composition corresponding to sepiolite have not been found.Taking into account the results from selected area electron diffraction and AEM-TEM, fibers of purepalygorskite and sepiolite have been found but it cannot be confirmed that all of the particles analyzedcorrespond to pure palygorskite or pure sepiolite because both minerals can occur together at the crystallitescale. In addition, the presence of Mg-rich palygorskite and very Al-rich sepiolite can be deduced.It is infrequent in nature that palygorskite and sepiolite appear together because the conditions forsimultaneous formation of the two minerals are very restricted. The chemical composition of the solutioncontrols the formation of the Allou Kagne sepiolite and palygorskite. The wide compositional variationappears as a consequence of temporary variations of the chemical composition of the solution.
PB Clay Minerals Society
SN 0009-8604
YR 2007
FD 2007
LK https://hdl.handle.net/20.500.14352/49746
UL https://hdl.handle.net/20.500.14352/49746
LA eng
DS Docta Complutense
RD 4 abr 2025