Résumé
Rodingites, composed predominantly of hydrogrossular, prehnite, pectolite, xonotlite, diopside and chlorite, have been recognized in the Nain Ophiolitic Complex (Iran). On the basis of petrographic and field data, two different stages of rodingitization from gabbroic protoliths are inferred. The first rodingitization stage,characterized by an increase in log a (Ca2+/Mg2+) and a decrease in the log a (SiO2 ) of the reactant aqueous fluids, is recorded by the crystallization of diopside and grossular-hydrogrossular leading to pervasive rodingitization. The second stage, corresponding to veined rodingite along brittle fractures led to the crystallization of pectolite, prehnite and xonotlite and is characterized by a decrease in log a (Ca2+/Mg2+) and an increase in log a (Si02).