102 THE VERMILION IKON-BEARING DISTRICT. 



the Vennilion series. Deposits in the schists are presumed to be of sedi- 

 mentary origin, the magnetite having been produced by hydrothermal 

 action from hematite, like that of the Keewatin. Those magnetites in the 

 massive rocks are of igneous origin and are analogous to the titaniferous 

 magnetite found in the gabbro. 



Hematite is the only ore actually mined on the Vermilion range up to 

 this time, and therefore the deposits of iron of this character are the most 

 important and the ones with which this report chiefly deals. 



The ore is always found in schistose or massive greenstone of Keewatin 

 age and is always associated with jaspilite. The ore bodies vary much in 

 size and are of lenticular shape, with long axis trending southwest-northeast, 

 parallel to the schistosity of the inclosing schists. 



The jaspilite and schist of the Keewatin are found to occur sometimes 

 minutely interlaminated ; at other times the jasper is in irregular layers, 

 which never have any great extent, and finally always pinch out; at other 

 times it is in oval forms, the greater lengths being parallel with the schistose 

 structure. Again, the jaspilite is in great fragments within the green or 

 massive diabasic schists, the masses having sometimes such relations with 

 each other as to show that they are a broken contiiaious layer. The 

 branches from the large bodies of jaspilite are supposed to be caused by 

 the crumpling, breaking, and squeezing of the entire rock structure, by 

 which the thinner sheets have been buckled out and thrust laterally among 

 the inclosing schists. The ore and jasper are regarded as a direct chemical 

 deep-sea precipitate from an ocean of hot alkalinic water which was 

 continually disturbed by acid rains and flows of basic lava due to volcanic 

 activity. The iron for the ore was extracted from the basic lavas. 



The rocks of the Animikie, equivalent to the Huronian and included in 

 the Taconic, consist chiefly of carbonaceous and argillaceous slates, with 

 siliceous slates, fine-grained quartzites, and gray limestones. At the bottom 

 of the series is a fragmental quartz sandstone, 300 feet in thickness, which is 

 named the Pewabic quartzite. The slates, conglomerates, and quartzites are 

 profoundly aff'ected and intermingled with eruptive material similar to that 

 found so abundantly in the Kewatin. These beds have the appearance of 

 consolidated beds of basic lava or of porous tufl^, but where this prevails 

 there is a sensible gradation from the dark trap-looking beds to the thin 

 beds of slate. At Ogishke Muncie Lake there is a slate cong'lomerate 



