SOUTH WESTERN NOVA SCOTIA. POWERS. 



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sufficient abundance for tfie rock to be called a quartz mon- 

 zonite. 



Rosiwal measurements of the mineral composition by weight 

 of this quartz diorite and of the Shelburne granite are given 

 for comparison: 



Barrington quartz diorite 



Oligoclase 54.6 



Albite-oligoclase 8 



Quartz 21.2 



Biotite 23.1 



Muscovite 3 



100.0 



Shelburne granite 



Oligoclase 35.2 



Microperthite 3.1 



Albite-oligoclase... 17.1 



Quartz . 33 . 6 



Biotite 7.8 



Muscovite 3.1 



Apatite 1 



100.0 



From these measurements the chemical composition has 



been calculated: 



Barrington Shelburne 



quartz diorite granite 



Si02 63.6 72.3 



AI2O3 16.8 15.2 



FesOa 2.0 .6 



FeO 3.0 1.1 



Mg 3.1 1.0 



CaO .- 3.3 2.5 



Na^O 4.8 5.0 



K2 2.1 1.5 



Rest 1.3 .8 



100.0 



100 



The most important characteristic of the granite and quartz 

 diorite is the high soda content. The two rocks are petro- 

 graphically related, the feldspar being of the same composition 

 and differing only in amounts as do the other constituents. 



