Two clays of the kaolinite type, one from Bihar and the other from Kerala, were each separated into particle-size fractions greater than and smaller than 1·4 µ.e.s.d. X-ray diffraction, differential thermal analysis, cation-exchange capacity and moisture absorption determinations and chemical analysis of the fractions showed that the micaceous mineral was concentrated in the fine fraction of one whereas it was mostly in the coarse fraction of the other. The evidence suggests that the mineral in the former belongs to the illite group and in the latter to the mica group.

The x-ray identification and crystal structures of clay minerals

The micaceous minerals in two indian clays

Kierunki przeobrażeń minerałów w starych zwałowiskach odpadów powęglowych

Vermiculite has a structure consisting of layered silicates surfaces interspersed with layers of water. When the expansion occurs intra lamellar clay water is removed. This paper aims to characterize the Vermiculite clay of Santa Luzia, Paraiba (Brazil) in their natural form, and after thermogravimetric treatments by classic X-ray diffraction analysis, thermal analysis and scanning electron microscopy. The results show that the method of expansion, using the technique of microwave energy is possible, however, the expansion factor is lower when compared to the indirect heating by the thermal expansion of the clay.

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Characterization of Natural Clay Vermiculite, Expanded by Indirect Method for Energy and Microwave

Über das Vorkommen von Chlorit im alpinen Salinar

XRD and DT A were utilized to investigate quantitatively the clay-mineral composition of the argillaceous rocks in four Miocene stratigraphic sequences located in western and southwestern Qatar. These rocks belong to the Dam Formation and are more concentrated in its lower Member "A" than in the overlying Member "B" which is dominated by a carbonate-evaporite facies. The reported clay-mineral suite consists of (in order of decreasing abundance): illite, kaolinite, attapulgite and Ca, Mg-montmorillonite. Illite and kaolinite are intimately associated and their crystallinity characters at a given stratigraphic horizon are closely similar. Well-crystallized attapulgite is present mainly in the marlstones especially those associated with evaporites. The occurrence of montmorillonite is restricted to the siltstones occupying the base of Member "A". Generally, Member "B" sequence consists of three thick illite-attapulgite-kaolinite zones alternating with two thin illite-kaolinite zones. Evidently, illite and kaolinite were formed by detrital inheritance from weathering horizons and/or soils on the Precambrian rocks in western Saudi Arabia. Montmorillonite seems to have been neoformed in the basin of deposition under conditions of alkalinity and high AI'+/Mg'"t ratios. It is also probable that the mineral was formed diagenetically through hydration of illite by pore solutions having high H+/K+ ratios. Attapulgite had also originated in the basin of deposition mostly by alteration of montmorillonite and/or magnesium-rich debris derived from weathered basic igneous rocks.

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The x-ray identification and crystal structures of clay minerals

Citations

The micaceous minerals in two indian clays

Kierunki przeobrażeń minerałów w starych zwałowiskach odpadów powęglowych

Characterization of Natural Clay Vermiculite, Expanded by Indirect Method for Energy and Microwave

Über das Vorkommen von Chlorit im alpinen Salinar

Distribution, genesis and thermal behaviour of clay minerals in the miocene argillaceous rocks in qatar, arabian gulf

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