THE 



JOURNAL OF GEOLOGY 



NOVEMBER-DECEMBER, iqoi 



THE FOYAITE-IJOLITE SERIES OF MAGNET COVE : 

 A CHEMICAL STUDY IN DIFFERENTIATION. 11.^ 



DISCUSSION. 



In the table below are given the chief molecular ratios of 

 those analyses of the Magnet Cove rocks which I am led to 

 believe are the most reliable and representative. There are also 



VIII 



SiOa 



TiO, ., 



AI2O3 



(FeO) 



M^O 



CaO 



NaoO 



K^b 



Molecular Ratio 



SiO, 



TiOs 



AUO3 



(FeOJ 



M^O 



CaO 



NagO 



KgO 



NagO 



K3O 



Specific Gravity . . . . 



60.20 



0. 14 



20.40 



3-44 

 1 .04 

 2.00 

 6.30 

 6.07 



1.003 

 .002 

 .200 

 .048 

 .026 

 .036 

 . 102 

 .065 



1.57 

 2.642 



I. Jaciipirangite. 

 II. Biotite Ijolite. 

 III. Ijolite. 

 VI. Arkite. 



'Continued from p. 622. 



Vol. IX, No. 8. 



V. Covite. 

 VI. Foyaite, Diamond Jo. 

 VII. Pulaskite, Braddock's quarry. 

 VIII. Pulaskite, Type, Fourche Mt. 



645 



