REPORT OF THE CHIEF ASTRONOMER 131 



SESSIONAL PAPER No. 25a 



tions which are probably not grossly astray — the leading constituents have 

 been roughly calculated as follows: — 



Quartz ' 52-0 



Albite : 23-0 



Paragonite 7-0 



Orthoclase 5-5 



Sericite 4-0 



Anorthite 3-0 



Epidote 1-0 



Magnetite, titanite, etc 4-5 



100-0 



Obviously these proportions are only approximate, but they will serve to 

 give a better conception of the rock than if no estimate of relative quantities 

 were made. In the discussion of the Moyie sills (chapter X) this analysis is 

 of primary importance, and it will be seen that even this estimate of weight 

 percentages is of value in the discussion. The analysis illustrates a general 

 characteristic of the Kitchener quartzite, — that it is highly feldspathic and is 

 rich in tbe alkalies, especially soda. The rock is chemically very similar to 

 pre-Cambrian graywacke from Wisconsin (analysis of col. 2 in the preceding 

 table).* 



It should be noted that this description of the typical quartzite differs, in 

 several essentials, from its preliminary description, given on pages 189-90 of 

 the writer's paper on i The Secondary Origin of Certain Granites,' published 

 in the American Journal of Science, Vol. 20, 1905. At the time of writing 

 that paper no chemical analysis of the rock was available nor was an adequate 

 number of thin sections at hand for the proper diagnosis of the rock. The 

 general lack of twinning among the feldspar grains led the writer to the 

 belief that orthoclase was the prevailing feldspar. The careful study of a larger 

 number of thin sections, following the receipt of Mr. Connor's results, per- 

 mitted the correction of the error in a second brief account of the quartzite, 

 published in the Kosenbusch Festschrift, 1906, p. 224. 



A prevailing characteristic of the formation is an abundant interbedding 

 of silicious metargillite in thin intercalations. Compared to the quartzite, 

 these are typically of a darker gray colour on the fresh fracture and weather 

 to a yet stronger brown than belongs to the weathered quartzite. Minute, often 

 interlocking grains of glassy quartz and clear or dusty feldspar are essential 

 constituents but they are subordinate to the now very abundant micas, both 

 biotite and sericite (or paragonite?). These dark interbeds simply represent 

 the more argillaceous phase of the same sediment which now forms the micace- 

 ous, feldspathic quartzite. There is no trace of original clayey matter and the 

 interbeds may be classed with the typical metargillites. 



Both slaty cleavage and true schistosity are notably lacking throughout 

 nearly the whole extent of the exposed Kitchener. Here again there can be 

 little doubt that the complete crystallization of these ancient shales has been 



*W. S. Bayley, Bull. 150, U.S. Geol. Survey, 1898, p. 87. 

 25a — vol. ii — 94 



