Plate XXVI.— .TASPILITE. 



Fig. 1. Folded jaspilite, from Jasper Bluff, Ishpeming. The illustration beautifully shows the second- 

 ary infiltration of iron oxide and deformation by combined fracture and flow. By close 

 observation iron oxide of three different ages may be seen. The oldest is the dark -gray 

 hematite. Intersecting this is the more brilliant steel-gray hematite and magnetite, and 

 cultiug both of the former are other veins of brilliant hematite and magnetite. The history 

 of the rock seems to be briefly as follows: Banded hematite and jasper was bent by folding, 

 probably while the rock was deei)-seated. During this folding the hematite was mashed. 

 In a later stage, when the rock was more rapidly deformed near the surface, fracturing 

 occurred. This gave the conditions for the first infiltration of iron oxide, and later, when 

 the rock was jierhaps still nearer the surface, further deformation resulted in new fractures. 

 Finally, the crevices thus formed were filled with the latest iron oxide. 



Fig. 2. Brecciated jaspilite, from Jasper Bluff, Ishpeming. The illustration gives evidence of the 

 history as shown by fig. 1. However, during the final process the layers of jasper, which 

 were bent at the earlier stage, were broken through and through, producing a breccia. The 

 same evidences are seen of three stages of iron oxide as in fig. 1. The less brilliant gray is 

 the earUest-mashed hematite; the intermediate gray represents a first infiltration; after 

 this there was shattering, and finally the breccia was cemented by brilliant steel-gray 

 hematite and magnetite. 

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