348 W. II. C SMITH — AUCIIKW ROCKS WEST OF I.Ak'K SUPERIOR. 



Tron Ores, [ron ores, in many places known to be rich and in others 

 reasonably presumed to be so, below the surface arc more or less abun- 

 dant in three distinct horizons. During the Last two seasons the writer 

 has discovered magnetic ores, free from sulphur, phosphorous and titanic 

 acid, in micaceous schist. probaMy of Contchiching age. These ores on 

 the surface arc of Low grade and intimately interbanded with the inclos- 

 ing rock, hut they may fairly be regarded as indicating extensive ore 

 bodies below the surface, probably of great economic value. 



The iron ores in association with the traps near the base of the Keewa- 

 tin in the Hunters Island region and north of the Atic Oban and Seine 

 rivers arc well known to western geologists. In the former locality they 

 are associated with jasper and are the extension of those great ore bodies 

 which form one of the wonders of Minnesota. In the latter locality the 

 ores are known to exist in extensive deposits and are of very high grade, 

 running as high as 70 per cent of metallic iron. Here as a rule no jasper 

 is associated with them. The ores of the same belt of Keewatin rocks 

 in which these occur, where found in the vicinity of Rainy lake, are often 

 so highly titaniferous that they are of little value in the present stage of 

 metallurgic science, but this seems to he but a local phase due to local 

 causes. 



The ores of the third horizon of the Steep Rock series are somewhat 

 problematical, hut there are indications of extensive ore bodies in these 

 rocks. 



Gold. — Gold has been mined in the Lake of the Woods in a feeble and 

 halt-hearted way for many years, hut the industry has languished under 

 many difficulties and misfortunes. Most of the quartz, however, is ex- 

 tremely rich, but the mining in almost every ease has been conducted 

 unscientifically, and the geologic problems connected with it have never 

 been properly worked out. Most of the gold-bearing quartz veins have 

 been found in the Keewatin rocks; but some of them, and these of 

 the richest, occur in granites, probably eruptive, usually coarse-grained 

 and chloritic, and somewhat resembling the quartz porphyry of the Atic 

 Oban river. These latter rocks are frequently found to contain very rich 

 auriferous quartz veins. The gold-bearing quartz porphyries of Harold 

 lake (north of the Seine river and about three miles west of Steep Rock 

 lake) are probably of the same age as the Margaret lake quartz porphy- 

 ries, though geographically the two are disconnected. It is possible that 

 the granites in the hake of the Woods, which contain auriferous quartz 

 veins, are of the same era of eruption as these. 



Nich liferous DioriU . Nickeliferous diorite has been recently discovered 

 in the vicinity of Rat portage, but as yet none has been found containing 

 a high percentage id' nickel. 



