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  • 1 Soil Science and Plant Nutrition, School of Agriculture University of Western Australia Neulands 6009 W.A.
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Thermogravimetry is a fast, accurate and highly sensitive method for the quantitative determination of halloysite, kaolinite and gibbsite in ∼10 mg altered feldspar grains from lateritic saprolite materials. A wide range in composition occurs between grains, and is evidence of the existence of various geochemical microenvironments within lateritic saprolite. Variations in dehydroxylation temperature of gibbsite and halloysite/kaolinite between the altered feldspar grains are an analytical artefact. The dehydroxylation temperature of gibbsite and halloysite/kaolinite increased from 242 °C to 302 °C and 454 °C to 491 °C respectively with the increase in the concentration of these minerals in the altered feldspar grains.