PETROGRAPHIC GEOLOGY AND DESCRIPTIONS. 743 



.Taspilyte. Breccia.] 



No. 1559. JASPILYTE. 



Stone mine, Tower, at the railroad cut. 

 Kef. Annual Report, xviii, page 61. 



Meg. Interbedded in No. 1558, i. e., in the green schist of the region. 



Mic, Insinuated amongst the quartzes and the grains of ore, and sometimes 

 extending sparsely throughout the rock, as seen in the slide, are shreds of 

 green hornblende, the element of the green schists, having a uniform elongation, 

 and plainly being a portion of the schists cotemporary with the jaspilyte. The 

 ([uartz is finely granular and interlocking, varying in fineness from band to 

 band. 



The most interesting portion of the slide is the siderite, which not only is in fine 

 grains, but in two instances is in crystals of considerable size in which are included 

 both quartz and iron ore grains. One section. 



Age. Archean (Keewatin). 



Remark. The fact that the siderite, which has been taken to be the source 

 of the iron ore of the Vermilion range, surrounds both the ore and the quartz, 

 shows that it is the latest of the elements to take its place, instead of being 

 the first, and the source of the ore. It is related to the oxides of iron and of 

 silicium as augite is related to labradorite in the well-known ophitic structure of 

 diabase. N. H. w. 



No. 1560. JASPILYTE. (Disintegrated. ) 



Dump of the Stone mine. 



Ref. Annual Report, xviii, page 01. 



Meg. Loose white quartz, a naturally disintegrated jaspilyte. 



Mic. The fineness varies; the grains are all angular. One preparation. 



Age. Archean (Keewatin). N. H. w. 



No. 1561. BRECCIA. 



Dump of the Stone mine, Soudan. 

 Ref. Annual Report, xviii, page 61. 



A beautiful breccia of jaspilyte and hematite cemented by quartz. The 

 quartz is commonly coarse grained like ordinary vein quartz, but in places 

 approaches the fineness of the jaspilyte quartz. In spots the quartz has not entirely 

 filled the spaces between the rock fragments, thus leaving cavities into which quartz 

 crystals project. No section. 



Age. Archean (Keewatin). u. s. G. 



No. 1563. BRECCIA. 



Dump at the scram southwest of the Breitung mine, Soudan. 

 Ref. Annual Report, xviii, page 61 ; Bulletin vi, pages 51, 422. 



