436 W. G. Foye — Nephelite Syenites of Ontario. 



state. R. Brauns* has described the scapolite bombs of the 

 Laacher See district. They, likewise, contain nephelite. 



P. D. Quenself has found vesuvianite, a mineral related to 

 scapolite, as a primary mineral in the canadites of Almunge, 

 Sweden. He concludes, "Hence the possibility must be con- 

 sidered that the vesuvianite is the remnant of a former assimi- 

 lation process." 



V. M. Goldschmidt:}: has recently described the enrichment 

 in soda of a sandstone having numerous calcite lenses. The 

 calcite lenses show an increase in their soda content of 2 - 58 per 

 cent. The lime was taken into solution and transported to 

 nearby slash veins, where it was redeposited as prehnite, clino- 

 zoisite, diopside, and scapolite. 



Geological literature has numberless examples of the enrich- 

 ment of calcareous rocks in soda. Some ascribe this to the 

 susceptibility of limestone to such replacement, but this is but 

 another way of saying that lime and soda easily are inter- 

 changed at high temperatures within an igneous magma, or, 

 for that matter, within the laboratory, as those who use the 

 J. Lawrence Smith method for the determination of the alka- 

 lies know. If this is true, the emanation of solutions high in 

 soda from a syntectic formed during the intrusion of a gran- 

 ite magma into limestone is to be expected. That such solu- 

 tion did enter the limestones of Haliburton County and 

 transform them to amphibolites has been shown by Adams 

 and Barlow. 



Conclusions. — The close association of granite pegmatite 

 with nephelite syenite indicates that they originated from the 

 primary granite magma at approximately the same time. If 

 they were segregated without the aid of foreign material, it 

 would seem that the low percentage of silica in one magma 

 and its presence in excess in the other should have been 

 adjusted by an interaction between the two. 



To the writer, it appears more reasonable to suppose that the 

 solutions which gave rise to the nephelite syenites had their 

 origin near the surface, that they were produced by the 

 reaction of limestone with granite magma, and that these 

 solutions enriched certain confined portions of the granite 

 magma in the elements characteristic of nephelite syenites. 



If the invading granite magma reacted with the various 

 lenses of limestone between which it was intruded, there would 

 be a possible source of soda solutions. That such solutions 

 were produced is shown by the differential transfer of soda 

 into the amphibolites. 



Harvard University, Cambridge, Mass. 



*R Brauns, Neues Jahrb. Min., Beil. Bd. xxxiv, p. 85, 1912; also xxxix, p. 

 124, 1914. 

 fP. D. Quensel, Centralbl. Min., No. 7, p. 205, 1915. 

 JV. M. Goldschmidt., Neues Jahrb. Min., Beil. Bd. xxxix, p. 193, 1914. 



