REPORT OF THE CHIEF ASTRONOMER 125 



SESSIONAL PAPER No. 25a 



Analysis of Crest on quartzite, Western Phase. 



Mol. 



Si0 2 82-10 1-368 



Ti0 2 -40 -005 



A1.0, 8-86 -087 



r&,0 3 -49 -003 



Feb 1-38 .019 



MnO -03 



MgO -56 -014 



CaO -82 -014 



Na,Q 2-51 -040 



K,6 2-41 -026 



HoO at 110°C -05 



H,0 above 110°C -37 -0120 



P;O s -04 



100-02 

 Sp.gr 2-681 



Assigning all of the soda to the albite molecule, one half of the lime to the 

 anorthite, the other half of it to titanite, apatite, epidote, and zoisite, the 

 weight percentages of the constituent minerals have been roughly calculated 

 as follows : — 



Quartz 58 



Albite molecule 21 



Orthoclase molecule 9 



Anorthite molecule 2. 



Micas, ca 



Accessories . - 3 



100 



It is quite possible that a considerable fraction of the soda should be 

 assigned to the sericite and even that paragonite itself is present. However, 

 from microscopic evidence it is probable that the soda-feldspar molecule is the 

 principal source of this alkali. The mineral percentages are, therefore, believed 

 to be nearly enough accurate to give a fair idea of the composition of the 

 average quartzite. It is clearly a quite highly feldspathic sediment. 



The only notable variation from this average composition of the typical 

 quartzite is found in the thin, darker, more micaceous and ferruginous laminae 

 which often interrupt the dominant light gray quartzite. These lamina?, vary- 

 ing from a centimetre or less to several centimetres in thickness, oftea. have 

 the habit of metargillite, but usually they are so acid as to rank among- the 

 impure quartzites. 



The specific gravity of the analyzed specimen, 2-681, is near the average 

 for the staple, light gray rock. The average for ten specimens typical of the 

 whole western phase is 2-698. 



The monotony of the western phase is seldom broken by' the appear... 

 of any lithological novelties. 



At a few horizons the micaceous material of the rock is segregated into 

 flattened spheroidal or more irregularly shaped, concretionary masses of all 

 sizes up to a foot or more in width. The greatest diameter of the coneret 



