842 THE GEOLOGY OP MINNESOTA. 



[Graywacke. Quartz. 



Age. Probably near the bottom of the Upper Keewatin. 



Remark. Such a rock might be called dioryte, and its present condition ascribed 

 to pressure and brecciatiou. Its evidently fragmental origin, however, is shown by 

 the photograph reproduced in plate W, in volume iv. Compare, also, plate Z, volume 

 iv, both of the final report. Compare, also, rock No. 1786. N. H. w. 



No. 2126. GKAYWACKE. (Janpilitic. ) 



Northeast corner sec. 36, T. 63-13 W. From a jaspilyte belt near the west end of Long lake. 

 fief. Annual Report, xxiv, page 43. 



Meg. A fine-grained, purple rock composed apparently of quartz, feldspar, horn- 

 blende (or chlorite) and a micaceous mineral. The rock resembles some of the fine- 

 grained graywackes that have been reddened by surface fires. 



Mic. A great number of small magnetite cubes are scattered through a finer 

 matrix of chloritic and hornblendic fibres and scales, fine feldspar fragments and 

 quartz. Some of the coarser opaque ores are of pyrite. The fine sparkling appear- 

 ance is caused by reflection from magnetite crystals. One section. 



Age. Keewatiu (probably Lower). 



Remark. In places this rock varies to a distinct jaspilyte, and as such has 

 attracted attention as an iron ore and been traced through the country for about a 

 mile. The rock blends with the country greenstone by acquiring more and more of 

 the hornblendic component. The structure of this belt resembles that seen at Moose 

 lake (No. 2180), but it is less conspicuously conglomeratic. N. H. w. 



No. 2127. QUARTZ. (Gold ore.) 



S. W. M S. W. M sec. 30, T. 63-12 W. 

 Ref. Annual Report, xxiv, page 44. 



Meg. White, vitreous, vein quartz, containing several minerals, as follows: 

 pyrite, chalcopyrite or other copper sulphides, galena, sphalerite (apparently), mala- 

 chite and azurite; also some granitic masses. 



An assay of this sample by Sharpless and Winchell gave the following results: 

 .24 ounce gold per ton and 6.04 ounces silver per ton, or $4.96 of gold and $3.62 of 

 silver per ton, gold being taken at $20.67 per ounce and silver at 60 cents. This 

 would make the ore worth $8.58 per ton. The ore (No. 2027) is a fair sample from 

 one of the test pits at this place, the pit which showed what appeared to be the best 

 ore. Other assays, by the same chemists, of ore from this locality, are as follows: 



i n in 



Gold, per ton, 5.16 .76 



Silver, per ton. 2.93 .48 .04 



Totals, - $8.09 $1.24 8 .04 



No section. 



Age. Vein in Archean. u. s. G. 



