W. G. Foye — Nephelite Syenites of Ontario. 425 



A small amount of zoisite is also present. Adams states 

 that the specific gravity of the scapolite is 2-711, which shows 

 that it is near the meionite end of the scapolite series. 



JBiotite is closely associated with the scapolite. When 

 biotite appears, nephelite disappears and scapolite or albite 

 takes its place. 



The kaolin is largely the decomposition product of the 

 nephelite. 



Chemical description. — The following is the analysis of the 

 type monmouthite as given by Adams and Barlow : * 



SiO, 



39*74 per cent 



The calculated norn 



Ti0 2 



0-13 



Anorthite 



12-51 



Al.O, 



30-59 



Nephelite 



67-72 



Fe,0 3 



•44 



Leucite 



8-28 



FeO 



2-19 



Olivine 



3-70 



MgO 



•60 



Akermanite 



•40 



MnO 



•03 



Magnetite 



•70 



CaO 



5-75 



Ilmenite 



•30 



Na,0 



13-25 



Pyrite 



•14 



K.O 



3-88 



Calcite 



4-92 



co 2 



2-17 









S0 3 



tr 





98-07 



CI 



0-02 



Water 



1-00 



s 



007 









H 2 



100 





99-07 



99-86 



Its position in the norm classification is as follows : — 



Class 1 Persalane 



Order 8 Ontarare 



Range 2 Monmouthase 



Sub-rang 4 __ Monmouthose 



4. Schistose Nephelite- Biotite Rock. 



Macroscopic description. — The eastern end of the northern 

 portion of the crescentic laccolith is composed of a bluish-black, 

 medium-grained and very schistose rock which is largely made 

 up of biotite. The biotite is in crenulated layers which form 

 wavy lines across the rock. Between these layers are lenses 

 of gray and pink feldspar and nephelite from a centimeter to a 

 centimeter and a half in length and from 8 to 10 mm. wide. 



Microscopic description. — An estimate of the percentage 

 amounts of the several minerals composing the rock, made by 



*F. D. Adams and A. E. Barlow, Memoir No. 6, Canada Geol. Snrv., 1910. 

 p. 276. 



