112 THE ROYAL SOCIETY OF CANADA 



Dykes of very similar minette or 'lamprophyre' from a few inches 

 up to many feet in width occur at the Tough-Oakes Mine, and on 

 other mining claims in the vicinity of Kirkland Lake. They are 

 approximately vertical, and follow the general strike of the conglom- 

 erate. 



Some of the widest of these dykes are again cut by small narrow 

 dykes, which stand out in relief on its weathered surface, and are much 

 lighter in colour than the adjoining rock. They are found to consist 

 chiefly of a soda or soda-lime feldspar, and are not dissimilar in 

 composition to the dykes of albite-diorite described below. 



A narrow dyke of bright green mica-lamprophyre, probably of 

 the same age as the above, and consisting of chlorite, orthoclase, some 

 plagioclase, calcite and phenocrysts of biotite (now represented by 

 chlorite) runs north-eastward across the claim of the Swastika Mining 

 Company, near Swastika Station, cutting both the greenstone and the 

 diorite-porphyry. It is closely associated with the principal gold- 

 bearing vein on the property. 



Albite-Diorite. In the railway cutting a short distance west of 

 Swastika Station on the T. & N. O. Railway, and in other places, dykes 

 of coarse red albite-diorite, not very dissimilar in composition to the 

 diorite-porphyry, cut through the Temiskamian conglomerate, and 

 alter it to some extent near the contact. The abundant feldspars, 

 which may compose 80% of the rock, are albite-oligoclase, in 

 which twinning and zonal banding are common. Biotite is bleached 

 or completely altered. The groundmass is fairly coarse, and consists 

 entirely of tabular plagioclase. 



Mr. Bruce^ gives the following analysis of a specimen from the 

 cut west of Swastika Railway Station 



indicating the presence of about 82 per cent of feldspar, chiefly Albite. 

 Granite and Syenite, younger than the Temiskamian Conglom- 

 erates are recorded by Mr. Burrows, who refers to them as follows: 

 "There are areas of granite and syenite within a short distance of 

 the gold deposits. An examination of a number of specimens from 

 these plutonic areas shows that these rocks contain albite, usually as 

 phenocrysts, similar to the feldspar-porphyry. It is quite likely that 

 the granite, syenite and feldspar-porphyry belong to the same period 

 of intrusion and are different faciès of a plutonic rock which underlies 

 the whole area. The syenite and granite have been exposed by deep 

 erosion." 



1 loc. cit. p. 263. 



