780 THE GEOLOGY OF MINNESOTA. 



[Kaolin. Greenwacke . Jaspilyte . 



Mic. The rock consists plainly of a fine debris of basic eruptive materials, in 

 which, with much decay, has been a generation of much calcite and some fresh /'</</- 

 .syw. It is much dimmed by chlorite and leucoxene. One section. 



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



No. 1449. KAOLIN (?) 



Stone mine at Soudan. 



Ref. Annual Report, xvi, page 126 ; Annual Report, xix, pages Ji r >, 127 ; Bulletin vi, pages 37, 422. 



Meg. A soft, greasy-feeling substance, white or greenish and pinkish white in 

 color. It is a much disintegrated schist. 



An analysis of this material is as follows: 



SiO 2 60.05 



A1 2 O, 27.55 



Fe 2 O, 1.30 



CaO .38 



MgO .77 



Na,O .31 



K 2 O 4.26 



P 2 6 .11 



H 2 O - 5.30 



Total, 100.03 



This would perhaps indicate kaolin mixed with some undecotnposed orthoclase. 

 No section. 



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



No. 1450. GREENWACKE. ( Grayivacke. ) 



Cut by the Tower spur track from the mines. 

 Ref. Annual Report, xvi, pages 113, 126. 



Meg. Light colored, greenish, siliceous, mainly massive. 



Mic. The rock has, microscopically, a decidedly schistose structure. It consists 

 of the usual ingredients of graywacke, but finer than is usual in graywackes. It has 

 a few spicules of actinolite, a little calcite and apparently a considerable zoisite, the 

 last generally in fine grains, giving its characteristic very low polarization colors, but 

 serving to give a light color to the rock, and by its high refractive index obscurity 

 to the slide between the nicols. One section. 



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



No. 1451. JASPILYTE. 



Sec. 2, T. 61-15 W. Southeast from Tower, five miles. 

 Ref. Annual Report, xvi, pages 113, 126. 



Meg. White and black-banded jaspilyte, the black bands being only in part of 

 magnetite. A little pyrite is present. No section. 



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



