888 THE GEOLOGY OF MINNESOTA. 



[Camptonyte. Esterellyte. Syenyte. 



same as rock No. 2279, and in part of white quartz. The latter is plainly of the same 

 date as the quartz described as permeating the red jasper of No. 2279. The whole 

 rock is evidently a secondary result of chemical infiltration in cavities within the 

 iron ore or its surroundings. These elements, especially the sulphur of the pyrite, 

 may be referred to the clastic (largely volcanic) greenstone in which the ore bodies 

 are embraced. No section. 



Age. It is unknown whether this jasper and pyrite are in the original rock con- 

 taining the ore of the Lee mine, or in the conglomeratic base of the Upper Keewatin. 

 Petrographically Nos. 2279 and 2280 much resemble the silicified " patchy " aporhyo- 

 lytes of the Keweenawan, suggesting the same petrology ; while they have an alliance 

 with the jaspilyte of the Vermilion Iron range, in that they consist solely of quartz 

 and hematite, the former embracing the latter in a poikilitic manner. N. H. w. 



SPECIMENS COLLECTED BY U. S. GRANT. 



No. 61G. CAMPTONYTE (?) 



Prom a dike in the granite at the falls of Gunflint river in N. E. % N. E. J sec. 13, T. 65-4 W. The dike 

 is on the Canadian side of the falls. 



Ref. Annual Report, xvii, pages 1GO, 161, 199, 204. 



. This rock is the same as No. 1318. 

 Aye. Archean. u. s. G. 



NO. 86G. ESTERELLYTE. 



Prom the point on which is the northwest corner of sec. 32, T. 65-6 W.; north shore of Keketjuabic lake. 

 Ref. Annual Report, xvii, pages 197, 205 ; Annual Report, xxi, pages 39-50. (This rock is the type of the 

 porphyritic facie.s of the granite here described.) 



Meg. This rock is the same as No. 1094, of which a complete description is 

 given elsewhere. Three sections. 



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



No. 344G. SYENYTE (in contact wi/Ji </////>// ibo/yte). 



Shore of Clearwater lake, E. % N. E. y sec. 32, T. 63-10 W. Here is an amphibolyte cut by stringers of 

 syenyte. 



Ref. Annual Report, xx, pages 41, 97. 



Meg. The specimen shows both rocks. The syenyte is. of medium grain and 

 reddish in color, and the amphibolyte is of about the same grain and contains a 

 little feldspar. In the syenyte near the contact of the two rocks the hornblende is 

 quite abundant. 



