THE IRON SERIES, CONTINUED. Ill 



low, draw a parallel between the more crystalline rocks and the 

 Vermilion schists on the one hand, and the more sericitic and 

 hydrated rocks of the Keewatin on the other. The latter consist 

 chiefly of a chloritic mineral, a sericitic mineral, a feldspathxc min- 

 eral, mostly plagioclase, and of hematite. The former exhibit a 

 hornblendic mineral, a micaceous mineral, a feldspathic mineral, 

 mostly orthoclase, and magnetite. A passage of one series of 

 rocks into the other is not at all an inconceivable metamorphic 

 process. These last mentioned magnetites are not as yet produc- 

 tive, although regarded as promising. There are titaniferous 

 magnetites in the gabbros and also other undeveloped hematites 

 in the Animikie. Still other magnetites occur in the Pewabic 

 quartzite, recently shown to be of value. The ores from Tower 

 and Ely are high-grade Bessemer, and are produced in great quan- 

 tity. Nearly 400,000 tons of all kinds were shipped in 1887 and 

 891,910 in 1890, making a grand total of 3,200,000. 



2.02.26. N. H. and H. Y. Winchell have argued that these 

 ores originated as marine chemical precipitates. The great extent of 

 igneous rocks associated with them leads to the suggestion that the 

 inclosing rocks have been formed by submarine volcanoes, whose 

 lapilli, etc., have largely contributed their materials. Deposits of 

 iron and silica are thought to have formed from the heated over- 

 lying waters. Somewhat similar views of the extensive ore bodies 

 of Elba are held abroad. 1 



The general geological relations are also discussed in many of 

 the papers cited under the other districts, especially those of Irving 

 and Van Hise. 



2.02.27. Example 9e. Mesabi Range. Of much more recent 

 development than the other districts is the Mesabi range of 

 Minnesota. The mines are not yet shipping ore (1892), but prom- 

 ise to in 1893. The indications are that the deposits are not less 

 extensive than in any other of the Lake Superior localities, if in- 



1 A. H. Chester, Eleventh Ann. Rep. Minn. Oeol. Survey, 155, 167. 

 T. B. Comstock, "Vermilion Lake District in British America," M. E., 

 July, 1887. H. V. Winchell, " The Diabasic Schists containing the Jaspilyte 

 Beds of Northeastern Minnesota," Amer. Geol., II. 18. N. H. and H. V. 

 Winchell, " On a Possible Chemical Origin of the Iron Ores of the Keewatin 

 in Minnesota," Amer. Oeol., IV. 291, 389; "The Taconic Iron Ores of 

 Minnesota and of Western New England," Amer. GeoL, VI. 263; "The 

 Iron Ores of Minnesota," Bull. VI. , Minn. Geol. Survey. Rec. Ann. Re- 

 ports of the Minn. Geol. Survey. 





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