AMPHIBOLE OF KAERSUTITE SERIES FROM ALKALINE ROCKS IN NORTH-WESTERN PART OF THE UKRAINIAN SHIELD

Abstract

Ferry-kaersutite as a rare mineral have been found in North-Western part of the Ukrainian Shield where alkaline-ultrabasic rocks of jacupirangite-melteigite series are widespread. Ferry-kaersutite occurs in essexite that form thin veins and apophyses from dikes of porphyry-like alkaline-ultrabasic rocks. By results of microprobe analyses ferry-kaersutites are of such composition (%): 39—40 SiO2; 4.6—5.07 TiO2; 14.6—14.9 Al2O3; 16.9—18.4 FeOtot; 7.95—8.09 MgO; 10.5—11.0 CaO; 2.4—2.9 Na2O; 2.7—2.9 K2O. In alkaline-ultrabasic rocks of this region different more magnesian amphiboles (pargasites, richterites, magnesio-riebeckite, katophorite and other intermediate varieties) are present. Some of these amphiboles are enriched in TiO2 (to 2.9—3.2%). It is assumed that studied ferry-kaersutite has formed at quick crystallization and partly contamination of alkaline-ultrabasic melts in veins and apophyses among country granitoids.