Plate XXVIII.— THE ORE DEPOSITS. 



Fig. 1. Generalized section allowing relation.s of all classes of ore deposits to associated formations. 

 On the right is soft ore resting in a V-shaped trough hetween the Siamo slate and a dike of 

 soapstone. In the lower central part of the figure the more common relations of soft ore 

 to vertical and inclined dikes cutting the jasper are shown. The ore may rest upon an 

 inclined dike, between two inclined dikes and upon the upper of the two, or be on both 

 sides of a nearly vertical dike. In the upper central part of the iigure are seen the relations 

 of the hard ore to the Negaiinee formation and the Goodrich quartzite. At the left is soft 

 ore resting in a trough of soapstone which grades downward into greenstone. 



Fig. 2. Sharply plicated jasper (black belts) and ore (white areas), showing shattering of the jasper 

 and concentration of the ore. The ore is proportionally greater where the folding has been 

 sharpest. Drawn from photograph from, southeast corner of Republic horseshoe. 



Fig. 3. Horizontal section of chimney of ore on east side of Republic horseshoe. The left side of the 

 ore is bounded by cross-joints. The right side is bounded in part by a sharp flexure passing 

 into a joint, and in part grades into the lean banded jasper and ore. Scale: 20':=1". 



Figs. 4, 5, and 6. Three cross-sections of ore in trough of soapstone grading downward into green- 

 stone. In fig. 4 the ore deposit is solid. In fig. 5 a dike oftshoots and nearly separates this 

 ore body into two parts. In fig. 6 the two dikes divide the same ore body into three parts. 

 Scale: 200' = 1". 



Fig. 7. Cross-section of National mine. On the left is soaiistone grading into greenstone. Above this 

 is hard ore, and overlying the hard ore are interstratified conglomerate, quartzite, and schist. 

 The ore is here plainly due to a replacement of the silica of the difterent sedimentary bands 

 by ore, although the original conglomerate was heavily ferruginous. Scale: 200 =1 . 

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