I92I. No. 8. GN TUE ECLOGITES OF NORWAY. 



The Almklov fa mi, Almklovdalen 

 East of Ekremsaeter, — „ — 

 Near Gusdalsvand, — ,, — 



Fiskaa, Vanelven 

 Dansen near Dalstjorden 

 Stensvik — „ — 



Tatjord, Nordalen 

 Seljenaes, Selje 

 Aasnaesnakken, Bryggen 

 Frøisaeter, Utviken, Nordtjord 

 Skvrfjeldet, Sande 



Disregarding such cases where much zoisite has been developed the 

 composition of the labradorites is rather constant, between Ab,, and Abgø. 

 Great variation is almost invariably combined with the development of 

 inverse zonal structure, very marked in the rock from Seljenaes 

 that will be described later, and e.g. in the specimen from Froisaeter, 

 Utviken. The latter is a fine-grained mvlonitic variety with the average 

 diameter of the plagioclase about o.i mm and much larger prisms of zoisite. 

 I measured the extinction angles in three grains cut J_ PM : 



(il border 30 , kernel 6" 

 (2I „ 28 , „ 18^ 



<3' •• 32 \ ..7' 



In the specimen from Gusdalsvand inverse zonality occurs in a rock 

 free from zoisite minerals; thus the phenomenon is not connected with 

 saussuritization. In other cases a faint normal zonality was obser\-ed, as 

 in the specimens from Dansen near Dalsfjorden. 



It is hard to find any valid explanation for the inverse zonal structure 

 in this case. 



We mav summarize our observations on the labradorite-rock in Nord- 

 tjord and More by comparing it with the labradorite rocks of the Bergen 

 and the Sogn regions. The present rock differs from the latter: (i) in 

 having amphiboles instead of pyroxenes; (2I in being more distinctly 

 foliated in structure and finer in grain; (3I in the smaller dimensions of 

 its intrusions. In the bulk composition, however, there is no notable 

 general difference, and a further similarity obtains in the occurrence of 

 fifarnet-bearinsf varieties and gradations into eclogites in both. 



