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



pyroxene granules a half a millimeter in diameter, associated 

 with red garnet in granules of the same size. Occasionally, 

 large crystals of pyroxene, from 1 to 5 cm. long and a 

 centimeter or more wide, are present. The rock is mottled 

 with grayish-white areas of calcite and albite which have a 

 border of red garnet against the pyroxene. 



Microscopic description. — The following minerals in approxi- 

 mately the given proportions are found in the contact rock : — 



Calcite 25 per cent 



Pyroxene 34 



Garnet 37 



Albite 3 



100 



Calcite, besides forming with pyroxene and garnet a ground- 

 mass of mosaic texture, occurs as minute blebs in the larger 

 pyroxene crystals. 



The garnet is often found as euhedral crystals. 



The pyroxene is apple-green in color and extinguishes 36-37° 

 on (110). 



The texture of the rock is allotriomorphic granular. 



Chemical description. — The following analysis is quoted 

 from Adams and Barlow.* The garnet-pyroxene rock just de- 

 scribed is more basic than the rock described by the above writers 

 as type I. Thelatter rock is intermediate in composition between 

 the garnet-pyroxene and the hornblende-nephelite rock. The 

 hornblende-nephelite rock corresponds closely to their type II. 



Analysis of type I of Adams and Barlow. 



Si0 2 43-67 per cent The calculated norm is : — 



TiO„ 0-78 Orthoclase 12-79 per cent 



Al a 3 20-91 Albite 22-01 



Fe a 3 3-54 Anorthite 20-29 



FeO 8-01 Nephelite 19-03 



MgO 1-46 Olivine 10-58 



MnO 0-05 Ilmenite 1-52 



CaO 7-37 Magnetite 5-10 



Na a O 6-73 Apatite -34 



K a O 2-25 Calcite 5-41 



P.O. 0-11 



CO, 2-37 97-07 



H„0 2-52 Water 2-52 



99-77 99-59 



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

 pp. 269-270. 



