I 92 I. No. 8. ON THE ECLOGITES OF NORWAY. 1 13 



100.59 



Sp.g. = 4.02. 



"d = 1-7823. 



RO : R.,0,^ : SiO., = 2.76 : i : 2.93. 



Composition : Fe^- Mn.jMg^yCaj^^. 



Concerning the other minerals the following ma\- be noted: 



About a half of the rock-mass consists of plagioclase, showing, on P, 

 extinction angles of 12 , corresponding to a labradorite. 



Another colourless mineral is scapolite of the wernerite series, especi- 

 ally frequent in the vicinity of the garnet crystals, but also found with the 

 other mafic minerals. 



Among the latter, brown hornblende is the most abundant, occurring 

 in groups of fine grains and associated with scaly iron ore. The horn- 

 blende has ,â = 1.670 + 0.003, corresponding, according to Ford's diagram, 

 to 14^0 FeO and 12 ^,0 MgO. The mineral shows a strong pleochroism 

 and other usual characters. 



A little brown biotite accompanies the hornblende and is also found 

 as coronas around crystals of ilmenite in the usual manner. 



The hypersthene is also arranged in groups of fine grains. These 

 show a faint greenish (y) and reddish la and ^) pleochroism and an axial 

 angle about x = 70 approximately, corresponding to about 40 mol. ^ 

 Fe SiOg. 



The groups of hypersthene are surrounded by coronas, or reaction 

 rims, essentially composed of green hornblende. This hornblende has a 

 little lower mean index of refraction than the brown one (ß = 1.670I. It 

 is speckled with minute rounded, isotropic grains of dark green colour, 

 apparentl}' spinel. 



Some of these reaction zones are still surrounded by another zone 01 

 garnet, this mineral thus appearing in two generations. 



Adding the apatite, the list of con.stituents should be complete so far 

 as the primary igneous and the posterior minerals of the amphibolite 

 facies are concerned. There are also some hydrated products ol de- 

 composition. 



Vid.-Sclsk. Skr. I. M.-N. K.1. 1921. No. 8. ^ 



