92 N N. Evans — Native Arsenic from Montreal. 



Art. VII. — Native Arsenic from Montreal ; by Nevil 

 .Norton Evans. 



At the end of last July, Mr. Edward Ardley, Assistant at the 

 Peter Red path Museum, McGill University, Montreal, brought 

 to the writer for identification a mineral found in a vein 

 cutting the nepheline syenite of the Corporation (Forsyth's) 

 Quarry near Montreal. The specimen proved to be native 

 arsenic* As far as the writer has been able to ascertain, this 

 mineral has been found at but two other localities in Canada : 

 on the west bank of the Fraser River, a short distance above 

 Lillooet, B. C. ;f and at Edwards Island, Thunder Bay District, 

 Lake Superior, nine miles east of Silver Islet4 The Montreal 

 occurrence is therefore quite remote from those previously 

 recorded, and it was thought that a careful examination and 

 description would prove of interest. 



The main portion of Mount Royal is formed of essexite, but 

 a later intrusion of nepheline syenite occurs on the northern 

 slope between the essexite on the one side and the Chazy lime- 

 stone of the surrounding plain on the other, the limestone 

 having been markedly altered thereby and rendered highly 

 crystalline. The nepheline syenite is grey in color and rather 

 tine in grain, and belongs to the foyaite type of this rock ; it is 

 composed of orthoclase, oligoclase, nepheline, and a hornblende 

 very deep green in color, allied to if not identical with 

 hastingsite, together with subordinate amounts of pyroxene, 

 garnet and nosean. The vein containing the arsenic was found 

 traversing the syenite nearly vertically, small horizontal string- 

 ers running off here and there, chiefly on one side, and a few 

 veinlets branching off and then running parallel to the main 

 vein. The vein was lenticular in form, having a width of one 

 and three-quarter inches in the widest part, and narrowing 

 down to about one-eighth inch above and below. The thicker 

 portion, which measured about ten feet vertically and three 

 feet horizontally, contained the arsenic, and probably forty 

 pounds of the mineral were removed. There is at present no 

 indication of another widening of the vein lower down, with a 

 further content of arsenic. 



Associated with the arsenic were found calcite in consider- 

 able quantity, with realgar and pyrites in exceedingly small 

 quantities ; in some places, where they occurred in druses, the 

 crystals of calcite (scalenohedra) were sifted over with very 



* See this Journal, xiv, 397. 



f Ann. Eeport Geol. Survey, Canada, 1896, part T, p. 9 ; and 1887-88, 

 part R, pp. 106, 161. 



X Ferrier : Canadian Record of Science, iv (1890-91), p. 472. 



