I 92 I. No. 8. ox THE ECLOGITES OF NORWAY. 5 I 



The amphiboles are regarded as not belonging to the eclogite faciee. 



Concerning the biotite and quartz we have no such structural evidence 

 to decide whether they are congenetic with the pyroxene and garnet or 

 not. It may be that they are trulv congenetic. 



Occasionally eclogites may contain e n s t a t i t e or olivine. Both 

 these minerals doubtless belong to the eclogite facies and their occurrence 

 depends on defined proportions of the chemical components present. 



Both oli\ine and enstatite,' or one of them at a time, may occur in 

 the band-shaped segregations in the olivine-rock. 



In the eclogite enclosed in gneiss, olivine was observed only in the 

 specimens from Lyngenes in Selje. 



Enstatite was found in the eclogite-pegmatite at Grytingvaag in Selje 

 and, moreover, in specimens of eclogite from Saetre on the island 

 Hareid and from the island Sule near Aalesund. This pvroxene 

 shows an axial angle of almost 90 \ Its crystals are surrounded b\- zones 

 of dusty opaque products of alteration (fig. 6, pi. II, a good diagnostic ol^ 

 the orthopyroxene in eclogites. In the rock from Hareid were still observed 

 euhedral pseudomorphic crystals of rhombic habit and lamellar structure, 

 probably pseudomorphs after olivine 



Cyanite, one of the most t\'pical minerals of the eclogite facies, has 

 not been met with in the eclogites of Norway. Its absence may be ascribed 

 to the chemical composition which, in tliese rocks, is characteristicall}' poor 

 in alumina; it occurs only when alumina is present in excess of that pro- 

 portion which may possibly enter into the combination of the pyroxene 

 and garnet present (cf Mineral Facies, p. 175I. 



In a certain sense the margarite, occurring in some varieties of the 

 eclogite, may be regarded as taking the place of the cyanite, although it, 

 being a hydrated mineral and occurring only in types showing much 

 evidence of alteration, does not belong to the facies. 



Among the posterior products commonly found in the eclogite we may 

 mention hornblende, plagioclase, epidote and zoisite, chlorite 

 and talc. 



The Eclogite in the Olivine-Rock. 



Mode of occiirroice and general cliaraeters. 



The first note on the eclogites among the olivine-rocks in Nonvay 

 was given by H. Reusch. In his first publication on the rocks of Sond- 

 more and Xordtjord' he called the rock a garnet-olivine-rock. He writes 

 as follows (in translation): 



• Loc. cit. (Forhandl. Vid. Selsk. 1877, p. 12I. 



