PETROGRAPHIC GEOLOGY AND DESCRIPTIONS. 745 



Jaspilyte.] 



No. 1568. JASPILYTE. 



From the out made for the high tunnel running south from the Tower mine where it crosses the light 

 " ore streak." 



Ref. Annual Report, xviii, pages 40, 62 ; Bulletin vi, pages 59, 60, 76, 422. 



Meg. The egg-shaped mass was entirely enclosed and isolated in the schists. 

 It showed somewhat peripherally concentric color bands, rather indistinct and 

 broad, hardly comparable with the banding of the jaspilyte and iron. 







Mic. There is nothing noteworthy different from the normal jaspilyte of the 

 region. It is a uniform mass of fine, interlocking quartz grains, with scattering 

 grains of hematite. One section. 



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



No. 1571. JASPILYTE. (Greenish.} 



Banded in the jaspilyte north of the Tower mine. 



Ref. Annual Report, xviii, page 62 ; Bulletin vi, pages 54, 78, 80, 422, plates II, IX. 



Meg. The rock appears in the main green, but has a large percentage of silica 

 and of iron. 



Mic. There is a banded variation in the relative amounts of the three elements, 

 iron, quartz and hornblende (or chlorite), producing the same structure as seen in the 

 ordinary jaspilyte. Indeed, this varies from the ordinary jaspilyte only in having 

 present a varying amount of the green element, which is identical with that of the 

 adjoining schists. It is sometimes distinctly green hornblende and sometimes 

 largely of chlorite. Two sections. 



Age. Archean (Keewatin). 



Remark. This specimen shows the alliance of the jaspilyte in its manner of 

 origin, with the enclosing green schists. N. H. w. 



No. 1572. JASPILYTE (ivitli xidi'i-itc). 



East end of the Stuntz mine ; east end of the North ridge, Tower. 

 Ref. Annual Report, xviii, page 62. 



Meg. Siliceous, white and red jaspilyte, with white granular veinings, one vein 

 being a quarter of an inch wide, effervescing feebly in cold HC1. 



Mic. The veinings are of siderite and cross the rock in all directions. The same 

 substance also permeates the red jaspilyte and is seen to surround the hematite grains. 

 One section. 



Age. Archean (Keewatin). 



Remark. There could be no better demonstration of the later date of the siderite. 



N. H. W. 



[NOTE. Nos. 1573 to 1606, inclusive, were collected in Ontario, outside of Minne- 

 sota territory, and only those are here described of which we have sections. Brief 

 field notes concerning the others can be found in the Eighteenth Annual Report, 

 pages 50-59, 62, 63.] 



