31 
SYENITE PORPHYRY OF BOISCHATEL TOWNSHIP, QUEBEC 
By H. C. Gunning 
CONTENTS 
Page 
Introduction 31 
General geology 31 
Description of the syenite porphyry 32 
Conclusions 40 
Illustration 
Plate III. Section of quartz crystal showing concentric arrangement of fine-grained 
groundmass 
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INTRODUCTION 
The area of syenite porphyry under consideration 1 lies in the west- 
central part of Boischatel township in the province of Quebec, some 13 
miles east of the Ontario boundary and about 12 miles west of Rouyn 
and the Noranda mines property. Renaud lake lies 3 miles southwest 
of the porphyry. A wagon road from Larder Lake, Ontario, to Rouyn, 
passes along the north side of Renaud lake, and a good trail leads from the 
lake to the Chance property situated on the south edge of the syenite 
porphyry. 
The occurrence was first mentioned by H. C. Cooke 2 . The writer 
studied the syenite porphyry during the summer of 1924, while acting as 
field assistant to Mr. Cooke. The time spent investigating the syenite 
porphyry was necessarily limited to some three days in all. About forty 
hand specimens, believed to represent the main types of the rock, were 
collected, and these along with twenty-five thin sections have been 
studied in the laboratory of the Massachusetts Institute of Technology, 
Department of Geology. Thanks are due Professors Waldemar Lindgren, 
and Joseph L. Gillson of the Department of Geology, Massachusetts Insti- 
tute of Technology, and Professor E. S. Larsen, of Harvard University, for 
advice and assistance during the laboratory study. 
GENERAL GEOLOGY 
The region is typical of the great Canadian Shield. It is a country 
of low relief, covered with a heavy mantle of drift, thickly wooded except 
where denuded by forest fires, and drained by sluggish, meandering streams. 
The area under consideration has been cleared of a large part of its timber 
and underbrush by fire and the rocks are well exposed in many places. 
However, much of the porphyry is still covered by swamp and brush, and 
'See Map: Opasatika Area, Timiskaming County, Quebec, Publication No. 1985, Geol. Surv., Canada, to 
accompany report by H. C. Cooke, in. Sum. Rept. 1922, pt. D. 
*Geol. Surv., Canada, Sum, Rept. 1923, pt, C I, p. 122. 
