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A B S T R AC T : The present study determined the mineralogy and thermal properties of kaolin from Acoculco (Puebla), at the eastern Trans-Mexican Volcanic Belt and compared it with the nearby deposits of Agua Blanca (Hidalgo) and Huayacocotla (Veracruz). The mineralogy of the kaolins was determined by X-ray diffraction, infrared spectroscopy and scanning electron microscopy. Thermal behaviour was studied by differential thermal analysis, dilatometry and hot-stage microscopy. The Acoculco deposit is composed mainly of kaolinite and SiO 2 minerals. In the case of Agua Blanca and Huayacocotla, alunite is abundant in places and minor anatase is also present locally. The Acoculco kaolins are Fe-poor and relatively rich in some potentially toxic elements (Zr, Sb, Pb). They undergo a relatively small amount of shrinkage (∼3-4 vol.%), during firing at 20-1300°C and cooling down to 20°C, except when >10 wt.% alunite is present. These kaolins are a suitable raw material for the ceramics industry. Other applications (pharmaceuticals, cosmetics) would require an enrichment process to eliminate impurities such as Fe oxides.

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Satellite imagery was used to assess the suspended sediment concentration (SSC) of the plume at the Grijalva river mouth, Gulf of Mexico. The SSC was calculated with the algorithm of Topliss. The algorithm was created for Lansdast 5 MSS. For this study it was validated the results for Landsat 7 ETM+ and Landsat 8 OLI. The depth of the ocean floor was measured using the speedtech sounder. The spectral response was registered with a GER-1500 spectroradiometer (with a measurement range of 296.71-1092.08 nm). The spectral responses were used to determine the size of the suspended particles and to perform the atmospheric correction. Spectral responses indicate that silt size particles predominate near the river mouth, whereas clay overtakes further towards the open sea. The trend in the river when water meets seawater, means an increase of suspended sediment towards the surface due to the lower density of fresh water, and the amount of sediment rises in the open sea. The correlation between the measurements in situ and SSC values produced by the algorithm demonstrates that the operation is suitable to estimate suspended sediments.