1921. No. 8. 



ON THE ECLOGITES OF NORWAY. 



39 



Sp.g. = 3-330- 

 ^ = 1.683 ~ 0.002. 

 Y — a = 0.024 '^^ max. 



2V ^67 appr. 

 Dispersion weak, p ^ v. 

 c : Y = 42 ' appr. 



Colour in thin section is faintly greenish, non-pleochroic. 

 The composition of this pyroxene is : 



Diopside 64.93 



Jadeite 28.84 



PseudoJadeite 7.75 



Unaccounted for — 0.97 



IOO-55 



The rutile, as usual, is the most prominent minor constituent, ap- 

 pearing as irregular or rounded grains of dark brown colour. 



The quartz and the mica were not separated, and their percentages, 

 very variable even in the small rock-body described, were roughly estimated 

 at 5.9 ^0 quartz and 2 ^,'0 mica. The bulk composition of the rock was 

 now calculated from the mode and the above analyses of garnet and 

 pyroxene. For the mica, which is moderately pleochroic, a = colourless 

 <^ ^ ^ Y = brownish yellow, 2E ^ 22 , was used the analysis of biotite 

 from quartz-monzonite, Walkerville Station, Butte, Mont (Quant. Classific. 

 table Xl\', analvsis c I. The following result was arrived at: 



