I9I5- ^'^^•4- 



REPORT OX ROCK-SPECIMENS. 



23 



St 



Naima Sahlbom. 



4707 % 

 1.62 > 



1545 * 



6.65 > 



6.50 » 



0.22 > 



No. 4. Awphibolile. Scott's Xiinataks. 

 Analv: 



SiO. 

 TiOo 



AUO:, 



FeO 



MnO 



MgO 



CaO 



Xa.O 



K2O 



PeOô 



S 



BaO 



6.49 

 10.29 * 

 1. 17 ^ 

 1.82 

 0.80 » 



0-55 » 



0.25 . 



0.87 » 



trace > 



99-75^0 



From these figures I have calculated the following approximate mineral 

 composition, taking into consideration the microscopic examination: 



Apatite 1.38 "0 



Pyrite i 03 ' 



Magnetite 4.08 ' 



Ilmenite i 54 " 



Titanite 1.99 » 



Biotite 1918» 



Amphibole 24.57 * ' 



Bytownite (Abi An^) . 39.60 > 



Quartz 6.35 ^ 



99 72% 



The whole content of K^O is calculated in biotite and amphibole. 

 Orthoclase is not present in the rock. However the high percentage of 

 K^O is unusual in an amphibolite, and attracts special notice. This high 

 percentage of K^O indicates that possibly the rock is not of pure igneous 

 origin, but is perhaps mixed witli sedimentary- material. 



The mineral composition: bytownite-quartz is also very unusual, and 

 belongs probabh' to an entirely metamorphic rock. 



