[en] This study aims at the mineralogical and physicochemical characterization of clays of
the Missour region (Boulemane Province, Morocco). For this, three samples were
collected in the Ghassoul deposit. The analyses were carried by X-ray diffraction
(XRD), X-ray fluorescence (XRF) and Scanning Electron Microscopy (SEM). The
thermal analysis from 500 to1100°C was also performed on studied samples, and the
fired samples were characterized by XRD and SEM. The XRD results revealed that raw
Ghassoul clay consists mainly of Mg-rich trioctahedral smectite, stevensite-type clay,
which represents from 89% to 95% of the clay fraction, with a small amount of illite
and kaolinite. The associated minerals are variable amount of quartz, dolomite,
hematite, gypsum and K-feldspars. The chemical analysis confirms the presence of Mgrich
smectite (stevensite) with largest amount in sample containing the highest MgO.
The SEM micrographs revealed the presence of automorphous structures with petalslike
shape typical of smectite. The Thermal transformations determined by X-ray
diffraction indicated that stevensite was transformed to enstatite from 800ºC. Diopside
starts to appear from 700°C, which is confirmed by SEM observations, and the quartz is
transformed to cristobalite when the temperature exceeds 1100°C.
