Barroisite-bearing Ecologite from Naustdal, Song og Fjordane, Norway

Chemical and mineralogical data are presented for the constituentsof an eclogite from Naustdal, Norway. Textural relationshipsindicate that the primary amphibole, a barroisitic variety intermediatein composition between glaucophane and common hornblende, formedin equilibrium with the omphacite, garnet, rutile, and apatite,but petrofabric evidence suggests that it crystallized somewhatlater. The petrogenesis of this rock is discussed in terms oftwo alternative hypotheses, namely of partly magmatic or ofstrictly metamorphic origin, but no definite conclusion canbe reached from the evidence available. The types of amphibole found in eclogites and their nomenclatureare reviewed.