Iron Ore Ranges of Minnesota. 



?7 



(13) Here you see the steam shovel at work, at the Mountain 

 Iron mine. From the mine the ore is dumped immediately onto a 

 railroad train. 



(14) This is a profile section showing the Mesabi ore and its 

 rocks lying upon the greenstone which is the prevailing rock of the 

 Vermilion range. 



(15) This shows the same, but here the massive greenstone of 

 the Vermilion is replaced by green schist and gneiss. The (raartsyte 

 seen at the bottom of the profile is the lowermost rock of the Me- 

 sabi range. 



(16) This is a section drawn from nature, illustrating the 

 conditions at the Mountain Iron mine when the ore was first dis- 

 covered. The outcrop of rock at the left attracted attention ami 

 was explored by more or less excavation. It showed some iron ore, 

 and was believed to be a "capping," so-called, of a bed of ore. But 

 no good ore was found in it nor about it. Then a test pit was sunk, 

 at some distance toward the south. This pit struck rich, soft heme- 

 tite ore, which, on being drifted toward the north showed that it 

 was underlain by quartzyte, and also, later, was found to grade in- 

 sensibly into a rock, here shown in outcrep, which was called taconyte. 



(17) The relation of the ore to this taconyte was for some time 

 a great puzzle. The ore was found overlying it, and underlying it, 

 and sometimes the ore was found to be embraced within the ta- 

 conyte, in pockets and large lenses, as seen in this profile section. 

 It required long and careful study of numerous pits, and of the 

 mines that were later opened, to prove conclusively that the ore was 

 produced by an alteration of some rock, of which the taconyt- 



its present representative. 



Fig. 18 — Mesabi Ore Disseminated in the Drift. 



(IS) This view shows the manner in which the ore is broken 

 down and disseminated in the drift of the region. 



9. The Rocks of the Mesabi Iron Range. 



If the two ranges differ in geographic location, and in the atti- 

 tude of the strata, and in the nature of the ore which they respect- 

 ively contain, yet the most striking feature of the Mesabi rocks is 

 their simplicity and uniformity of composition, as contrasted with 

 the complexity of the rocks of the Vermilion range. If the taconyte 



