8 



J. SCHETELIG. 



M.-N. Kl. 



Calculating the plagioclase according to the microscopical determination 

 as oligoclase, Ab^Ani , the composition of the rock is as follows : 



Oligoclase Ab4Ani 

 Microcline -f- Albite 



28.20 ^/0 

 46.39 » 



F'elspars 



74-59 % 



Quartz 24.18 



Other constituents 1.77 



100.54 % 



The rock represents nearly a pure quartz-felspar-mixture and the 

 proportion quartz : feldspars (Qu : Or -\- Ab -|- An) shows close agreement 

 with the "granitic eutectic" according to Vogt ^ 



The plagioclase-gnviite shows under the microscope plagioclase as 

 the only felspar. In external appearance this rock does not differ from 

 the specimens of the ordinary granite with potash-felspar in excess ot 

 plagioclase. Dr. Naima Sahlbom also undertook the analysis of this rock. 



No. 2. Plagioclase-granite . Mt. Betty. S. Victoria Land. 

 Analyst: Naima Sahlbom. 



SiO., 



TiOo 



ALO, 



FeoO;, 



FeO 



MnO 



MgO 



CaO 



Na.O 



K.,0 



BaO 



P2O, 



S . 



HoO-'°°' 



HoO^'««' 



Ï 00.43 0/0 



1 J. H. L. Vogt: Ueber anchi-monomineralische und anchi-eutektische Eruptivgesteine. 

 Vid. Selsk. Skr. I. 1908. No. 10. 



2 Average of two determinations of KoO : 1.17 "0 and liçOq- 



