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Dear all, Your lively discussion on metasomatism entertained me a lot. However, please consider the following not uncommon situation: Starting material is a pure monomineralic dolomite marble. The marble reacts with an SiO2-saturated fluid advecting on fractures cutting across the marble. The resulting metasomatic rock consists of about 70 vol.% tremolite and 30 vol.% calcite. This means that the original rock consists of one phase (dolomite) and the metasomatic rock consists of two phases (Tr + Cal). This is a 100% increase in the number of phases from the source rock to the metasomatic rock. Say hello to Mr. Kozinski. Korzinski, of course, was not wrong. But the counting of components, phases, mobile components, independent variables and all that is to complex for the average geologist to be of any practical use. Cheers Kurt Bucher-Nurminen, K., 1981, The formation of metasomatic reaction veins in dolomitic marble roof pendants in the Bergell intrusion (Province Sondrio, Northern Italy). Am. Jour. Sci., 281, 1197-1222. Bucher-Nurminen, K., 1989, Reaction veins in marbles formed by a fracture-reaction-seal mechanism. European J. Mineral., 1, 701-714. Bucher, K., 1998, Growth mechanisms of metasomatic reaction veins in dolomite marbles from the Bergell Alps. Mineralogy and Petrology, 63, 151-171. -- Kurt Bucher (Prof. Dr.) Institute of Mineralogy and Geochemistry University of Freiburg Albertstrasse 23b D-79104 Freiburg Germany Phone 49-761-203-6395 (direct) 6396 (general office) 6407 (FAX) http://www.minpet.uni-freiburg.de [log in to unmask]