PLATE XIII. 



IRON ORE DEPOSITS IN PITCHING TROUGHS. 



(Both ore exploited and ore now in mine are represented as ore, since the purpose of this plate 

 is to show the manner of the development of the ore rather than the present stage of exploitation. ) 

 Fig. 1. Vertical north-south cross section of Chandler mine, showing relations of the ore deposit 

 to the soap rock, Ely greenstone, and ore-bearing formation. The iron ore is in a broad 

 U-shaped trough, bottomed by soapstone or paint rock which grades down into greenstone. 

 It is capped by the ore-formation material. At the place where the cross section is made 

 the ore does not extend to the surface along either limb. Therefore, at the particular place 

 where this cross section exists, although there is a very large ore deposit below the surface, at 

 the surface the only rocks which are found are the greenstone, soapstone and iron-bearing 

 formation. 

 Scale: 1 inch equals 250 feet. 

 Fig. 2. Vertical east- west longitudinal section of Chandler mine, showing the same relations as fig. 1. 

 The figure very well illustrates how the ore body increases in size from the surface. Where 

 the ore reaches thedrift its area is small; and this great ore deposit, which extends eastward, 

 where it constitutes the Pioneer mine, is below a heavy capping of the ore-bearing for- 

 mation. 

 Scale: 1 inch equals 250 feet. 



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