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This study concerns thick layers of isovolumetric transformations products developed from Miocene phonolite, in the uplands of Central Kalimantan Province (Borneo). The study of this unusual alteration material is carried out by means of chemical and thermal analysis, of X-ray diffraction and of electron microscopy. The wax-like isovolumetric alteration material shows a density close to 2.4 and a very low porosity ranging from 10 to 10 %. There are no more remains of minerals of the original rock, but the initial volume seems to be perfectly preserved. The clay material of these alterations is mainly composed of well-ordered kaolinite mixed with a small amount of 2 :1 clay minerals. Mass-balance calculation shows that the alteration material contains 40 to 60 % more AI2O3 than the same volume of the initial rock. This increase in AI2O3 is on a par with a similar increase in ГегОз and ТЮ2. For trace elements, this increase varies according to each element, ranging from 15 to 30%., Sieffermann G., Tjojudo Suharto. Evidence of mobility and input of AI, Fe, Ti and trace elements in altered volcanic rocks from Kalimantan, Indonesia. In: Proceedings of the 9th international Clay Conference, Strasbourg, 1989. Vol I : Clay-organic interactions. Clay minerals in soils. Strasbourg : Institut de Géologie – Université Louis-Pasteur, 1990. pp. 109-117. (Sciences Géologiques. Mémoire, 85)