400 



DALE— CAMBRIAN MANGANESE DEPOSITS OF [April 25, 



lar with nodules, lenticles, and bands of the green jaspery carbon- 

 ate and oxide of manganese. Wherever the jaspery minerals occur 

 in the red band, whether as nodules, lenticles, continuous or non- 

 continuous bands, they present or suggest concretionary character- 

 istics. The red bands are locally pyritiferous and barytic. Red 

 shale occupies the greater portion of the bed. 



Microscopic examination of this red band brings out very little, 

 other than that it is distinctly hematitic with the hematite occurring 

 as a pigment or as irregular accumulations (Fig. 23, Slide 276). 



Fig. 23. Microphotograph of banded manganese ore with barite, from 

 219 Ay; slide 276; enlarged 9.5 diam. a, red band; b, green band; c, barite. 



The chemical analysis of this band is as follows : 



Analysis E. 

 Red Bands. 



SiO, 

 Fe,63 

 FeO 

 ALO. 



27.61 

 4-25 

 1.69 

 6.96 



MnO 26.05 



CaO 



MgO 



RO, 



H3O 



CO. 



• 9-94 



• 349 

 , 471 

 ■ 473 



10.57 



100.00 



Analysis E i. 

 Recalculation. 



MnO 19.71 



MnCOa 10.23 



MgCOs 7.25 



CaCOs 7.50 



Ca3(PO,), 10.31 



SiO. 19.44 



H,0 1.87 



2H,0-AL03-2SiO, + FeO .... 19.01 

 FeoOs 4.25 



99-57 



