i8o The Ottawa Naturalist. [January 



A PRELIMINARY NOTE ON AN AMYGDALOIDAL TRAP 

 ROCK IN THE EASTERN TOWNSHIPS OF THE 

 PROVINCE OF QUEBEC, 



By John A. Dresser, Richmond, Que. 



A few years ago Mr. J. C. Sutherland called the writer's atten- 

 tion to an apparently peculiar occurrence of feldspar in sedimentary 

 slates in the vicinity of the old St. Francis copper mine, near 

 Richmond, and on subsequent reference to the following descrip- 

 tion of the occurrence by Sir William Log-an (Geology of Canada, 

 1863, pp. 606-607), suggested a microscopic examination which it 

 has not yet been found possible to carry out. But from several 

 observations made at various times, it is evident that the rock is 

 one of considerable scientific interest and economic importance. 



It was thus described by Logan, " Orthoclase is found 



under remarkable conditions among the argillaceous rocks at the 

 St. Francis copper mine in Cleveland. Here beds of a soft, fine- 

 grained, somewhat schistose dark bluish-gray argilllte enclose 

 small ovoidal or elongated masses of crystalline feldspar, which 

 have a general parallelism, and are oblique to the divisional planes 

 of the rock. The laminae of this conform to the feldspathic 

 masses which give a knotted surface to the exterior of the rock. 

 These are in some portions from one eighth to one-tenth of an inch 

 in diameter, and are nearly spherical, or elongated two or three 

 diameters. In other portions of the rock they are an inch or more 

 in length, and more irregular, though always rounded in outline. 

 The exterior ot the nodules is a white or pinkish feldspar. In 

 some parts the feldspar is seen to extend from the nodules, in thin 

 layers among the laminae of the slate, giving to such portions a 

 gneissoid aspect. In most cases, however, the rock has com- 

 pletely the aspect of an amygdaloid : especially in sections which 

 exhibit the feldspar surrounding the quartz in the ovoidal masses." 



Epidote also forms the cores of some of these masses, while 

 the material of others, though not certainly distinguished from 

 orthoclase by its physical properties, yields much water when 

 heated in the closed tube, and hence is probably a zeolite in part 

 at least. Veins of calcite as well as masses of chlorite, specular 



