114 THE ROYAL SOCIETY OF CANADA 



On the Burnside Claims a dyke of fine-grained diabase, now largely- 

 altered to calcite, runs north and south, almost at right angles to the 

 strike of the other rocks, and on the line of the dyke the older rocks 

 appear to be considerably faulted and thrown. 



Sesekinaka} In the Sesekinaka District, which lies a short dis- 

 tance North West of Swastika, gold-bearing quartz veins are associated 

 with reddish diorite-porphyry or Albite-diorite and lamprophyre, 

 very similar to those at Swastika, and probably of about the same age, 

 though I did not see any outcrops of the Temiskamian rocks in con- 

 nection with them. 



Munro.'^ Twenty-five miles north of Sesekinaka, in the townships 

 of Munro and Guibord, the folded slates, quartzites and conglomerates 

 of Temiskamian age, as well as the greenstones of Keewatin age, are 

 cut by a number o quartz veins containing an appreciable quantity 

 of gold. Some of these veins cutting the Temiskamian slates are very 

 closely associated with, and even occupy the same fracture planes as, 

 dykes of green mica-lamprophyre similar to that which cuts the green- 

 stone and porphyry at Swastika. 



While the veins occur in the folded Temiskamian rocks they 

 have not participated in the folding, but have been formed at a later 

 date, most likely in association with the intrusions of lamprophyre 

 which probably occurred in Algoman times. 



Larder Lake. Twenty-five miles east of Swastika is the Larder 

 Lake District, near the border line between the Provinces of Ontario 

 and Quebec, in which gold associated with pyrite has been found in 

 and near a number of quartz veins. 



The rocks are similar in character and age to those at Kirkland 

 Lake, though an old dolomite is rather more abundant. Mr. Wilson^ 

 gives the following description of the porphyries which he includes 

 in the Keewatin. "The microscopic study of the quartz porphyry 

 shows the rock to consist of phenocrysts of quartz, orthoclase, and 

 plagioclase, enclosed in a matrix of quartz and feldspar, usually ac- 

 companied by some carbonate and chlorite. The plagioclase pheno- 

 crysts range all the way from albite to labradorite, but the alkalic 



^ See A. G. Burrows and P. E. Hopkins. "The Kirkland Lake and Swastika 

 Gold Areas," pp. 34-35. 23rd Rep. Ont. Bur. Min. Part H, 1914. 



and C. Spearman "Rocks and Ore Deposits at Sesekinaka." Can. Min. Jour. 

 Feb. 1, 1915, pp. 69-73. 



^ For the age ( f these recks see Map 21c "Munro and Guibord" in Rep. Ont. 

 Bur. Min. Vol. XXI Pt. 1., Toronto, 1912. 



3 M. E. Wilson. "Larder Lake District." Mémoire 17E Geol. Survey of 

 Canada. Ottawa. Govt. 1912. 



See also R. W. Brock. "The Larder Lake District," 16th Rep. Ont. Bur. Min. 

 1907, pp. 202-218. 



