416 W. G. Jboye — Nephelite Syenites of Ontario. 



The limestone, north of the laccolith, has been eroded from 

 beneath the red syenite. The latter rock has broken down and 

 has formed a talus-slope which conceals the contact of the 

 two rocks. Drift likewise covers the contact of the canadite 

 with the nephelite pegmatite. 



The contact of the nephelite pegmatite with the overlying 

 limestone is marked by a kaolinized zone a foot or two wide. 

 Coarsely crystalline calcite is included in blebs in the kaolinized 



Fig. 3. 



1 









■riOS^"" 





45^" 

 :\ 1 



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1 



1 



i 



.••■•••.. 50 ..-■■' 



.....•-■■ ■" "' o - 



' •""'*' O 0....2.O e " O ;' 

 . ■ • " * o "*"*-. * 

 o.-'o ■ O*. O 



" ■ ■'...' 



V 



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o 







40> 



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■..••' 35 ' 5 



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52; 



^t<Sj£j£> L 





"^rr3^^ 4 ° 25 ° 



500 ft.. J 



Fig. 3. Distribution of the several rock types in the Gooderhara Laccolith. 

 l = Red syenite, 2=Schistose canadite, 3=Nephelite pegmatite, 4=Am- 

 phibolite, 5= Granite pegmatite. 



material. Scapolite, apple-green apatite, and some pyrrhotite 

 are also associated with this rock. With increase of calcite 

 the kaolinized zone passes into the normal limestone. 



Petrography of the Gooderham Laccolith. 



Figure 3 shows the general distribution of the rock types 

 associated with the Gooderham laccolith. 



1. Red Syenite. 



Macroscopic description.- — This rock is reddish gray in color, 

 rather fine in grain and even-textured. It is composed pre- 

 dominantly of pink feldspar in grannies 1 mm. in diameter. 

 Occasional crystals of white feldspar are likewise present. 

 Flecks of black mica and some hornblende are evenly dis- 

 seminated through the rock and are arranged in such a way 

 as to produce a vague schistosity. The rock is very fresh, 

 breaks with an irregular fracture, and is of average weight. 



