On Some Dykes Containing Huronite. 27 



was lost. Mr. H. G. Skill, of Cobourg, Ontario, who assisted the 

 writer in 1S91, discovered another dyke containing this mineral, about 

 one quarter of a mile north of Murphy Lake, in Timber Limits 90' 

 Algoma District. During the progress of his explorations in the 

 peninsula of Labrador, Mr. A. P. Low, of the Geological Survey of 

 Canada, noticed the presence of Huronite in a dyke cutting Laurentian 

 gneisses about ten miles north of Lake Kawachagami on the portage 

 route between the Rupert and Eastmain rivers and also in two dykes, 

 each about two hundred yards wide, breaking through rocks of Cambrian 

 age, on the west branch of the Hamilton River, fifteen and twenty 

 miles respectively, below old Fort Nascavvpee, on Lake Petitsikapow. 



Dr. Harrington (private communication) has noticed loose pieces 

 of diabase containing Huronite a few miles beyond Amyot Station. He 

 also mentions the occurrence of a diabase dyke four inches in width, 

 containing phenocrysts of the same mineral, a short distance east of the 

 crossing of the Magpie River, near Otter Station, on the Canadian 

 Pacific Railway. 



Prof. N. H. Winchell, of Minneapolis, Minnesota, in his 

 visit to the Lake Huron district, in 1SS9, made note of "the 

 occurrence at Algoma of occasional very interesting boulders 

 (1605). (1) They contain large and small rounded whitish green 

 felspathic spots which are distributed somewhat like porphyritic 

 crystals but they have not the regular periphery of crystals. They 

 are in a matrix of ordinary diabase of dark green colour and the 

 spots make the rock noticeable, their largest size being somewhat larger 

 than an inch in diameter. Some of the boulders are put in the 

 foundation of the great hotel which the Canadian Pacific Railroad (2) 

 projected at Algoma, and that is where we saw them first. Dr. Selwyn 

 recalled the dyke cutting the Animikie on the high ridge back of Silver 

 Islet, as the only spot where such a rock is in place," Professor 

 Winchell, who visited this place in 1879, has sent me a small chip from 

 a specimen then collected, as well as fragments of the Algoma boulder 



(1) The number 1,605 refers to the number of the specimen in the rock series of 

 the Geological Survey of Minnesota 



(2) iSth Annual Report, Geological Survey, Minnesota, 1889, pp. 58 and 63. 



