A detailed characterization of some minerals of the kaolinite group has been done. Themineralogical and structural characterization has been conducted by X-ray diffraction (XRD)together with the study of the spectroscopy response in the visible-near infrared and short wave(VNIR-SWIR), and the main objective was the determination of kaolinite polytypes. For thispurpose, 13 samples were selected from a wide group of samples.
X-ray diffraction patterns confirm the high purity of all the samples which only present scarceamounts of quartz or feldspar in certain cases. The detailed study of XRD patterns allowsidentifying characteristic reflections and small features of each polytype as well as to obtaincrystallinity indices for each sample. The statistical analysis of the patterns groups the samplesaccording the kaolinite polytype in 5 kaolinites, 2 dickites and 6 halloysites.
The spectroscopic study (VNIR-SWIR) of kaolin samples shows different features in thewavelength range studied with the ASD FieldSpec 4 Standard-Res. Groups of diagnostic peaksfor kaolinite, dickite y and halloysite polytypes have been identified in the second derivative ofthe spectrum, of which position and intensity have been treated statistically with the aim ofclassifying the spectra according to the polytype. In good agreement to the XRD results, thestatistical analysis of the spectroscopic data, both by cluster analysis and by principalcomponents analysis (PCA), allow an unequivocal classification of the samples according to thepolytype from their VNIR-SWIR spectra.

The x-ray identification and crystal structures of clay minerals

Field spectroscopy applied to the kaolinite polytypes identification

/pdf/clay-mineralogy-of-late-pleistocene-sequences-in-xx3jlhpar8.pdf

Clay mineralogy of late Pleistocene sequences in northwestern Washington and southwestern British Columbia

Ce memoire est axe sur l'utilisation de traceurs isotopiques radiogeniques (Strontium, Neodyme, Plomb) et stables (Bore...) dans les etudes environnementales et tout particulierement le long du cycle de l'eau. Les circulations et les interactions des eaux, qu'elles soient de surface ou souterraines, avec les roches encaissantes sont de plus en plus renseignees par l'utilisation de la geochimie et tout particulierement par l'application des tracages isotopiques. Illustree par plusieurs exemples dans differentes regions en France et Europe, la compilation d'etudes presentee ici repose principalement sur les systematiques isotopiques du strontium, du neodyme, et du plomb (couplee avec les determinations elementaires Sr, Terres Rares, elements traces). Elle permet de definir pour chacun des sites ou systemes etudies, l'origine naturelle ou non des elements chimiques, leurs comportements, leur transport dans des compartiments differents (e.g. forme dissoute et/ou particulaire pour les fleuves), des schemas de circulation des eaux et fluides profonds et les interactions entre les eaux et les differents types de roches encaissantes. Pratiquement, cette compilation est organisee en trois parties distinctes et recouvrant les trois grandes etapes du cycle de l'eau : precipitations, eaux de surface, eaux souterraines.

https://tel.archives-ouvertes.fr/tel-00931740/document

Le cycle de l'eau de l'aérien au souterrain : voyage des isotopes

Hacettepe University, Faculty of Engineering, Dept. of Geol. Engineering, 06100 Ankara, Turkey(Received 15 December 2010; revised 2 April 2013; Editor: George Christidis)ABSTRACT: Alkali- and Ca-rich smectites occur in association with Neogene lacustrinesedimentary rocks and high-K calc-alkaline volcanic rocks with compositions ranging from andesiteto rhyolite in western Anatolia (Turkey). Major clay occurrences are associated predominantly withthe Foc¸a and Akc¸ako¨y ignimbrites and with the ignimbrites within the Rahmanlar pyroclastics.Experimental studies indicate that the main clay minerals present are Na- and Ca-smectite andsubordinate illite, associated with silica polymorphs, trace clinoptilolite and chlorite. The authigenicminerals formed by weathering and metasomatic reactions between hot volcanic material and lakewater. Smectite was produced as a result of argillic alteration of the volcanic glass and feldspars ofthe ignimbrites, Rahmanlar pyroclastics and reworked volcaniclastic sediments through chemicalweathering and dissolution-precipitation processes and formed as authigenic phases both in terrestrialand nearby shallow lacustrine environments under prevalent humid or semi-humid climate during theNeogene.

Alteration of glassy volcanic rocks to Na- and Ca-smectites in the Neogene basin of Manisa, western Anatolia, Turkey

The various high- and low-quartz solid solutions (stuffed derivatives of quartz) synthesized so far are enumerated; their crystal chemistry is discussed in terms of parameters like co-ordination, effective ionic radius and site preference of the candidate cations for such structures. Conditions of synthesis and stability/metastable persistence of these solid solutions are surveyed and their characteristic properties are summarized.

The x-ray identification and crystal structures of clay minerals

Citations

Field spectroscopy applied to the kaolinite polytypes identification

Clay mineralogy of late Pleistocene sequences in northwestern Washington and southwestern British Columbia

Le cycle de l'eau de l'aérien au souterrain : voyage des isotopes

Alteration of glassy volcanic rocks to Na- and Ca-smectites in the Neogene basin of Manisa, western Anatolia, Turkey

Crystal Chemistry, Synthesis and Characterization of Quartz Solid Solutions: A Review

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