Experimental Investigation of the Upper Thermal Stability of Mg-rich Actinolite; Implications for Kiruna-Type Iron Deposits

The occurrence of actinolite in magnetite deposits of possible mag-matic origin has prompted an experimental investigation of theupper thermal stability of Mg-rich actinolite to determine how thestability of actinolite changes with increasing Fe content.Experiments were carried out primarily on the compositionalre-equilibration of natural tremolite [molar Fe/(FeþMg)¼Fe-number ¼0 014] in the presence of synthetic clinopyroxene(Ca