MINES POTOSI DISTRICT. 



699 



usually in vertical sheets, and without any of the associate vein-minerals which are usu- 

 ally found in the other mining districts. 



FIG. 14. 



POTOSI DISTRICT. 



Mining operations here are chiefly confined to the winter season, and furnish employ- 

 ment to about twenty miners. 



The old ranges of the Potosi diggings re included in Sees. 33 and 34, T. 3, R. 3 W. 

 Their general course is about N. 70 W., although some bear a few degrees more to 

 the west, and some a few more to the north. They numbered about thirty in all, which 

 were considered as separate and distinct ranges ; and in addition there were many 

 smaller crevices not sufficiently important to constitute ranges by themselves. 



Among the more important were the Long, Wooley, Gillet, Gilmore, Smith, Polking- 

 horn and Barbara, some of which were over a mile in length. 



The productive portion of these ranges is confined to the middle and lower portions of 

 t! ie Galena limestone, none of the crevices having as yet been proved as low as the 

 Brown rock; the ore is usually found in sheets of varying thickness. 



Considerable irregularity exists in the form- 

 ation of many of the crevices in the Potosi 

 district, by which, they seem to split up 

 in the lower beds of the limestone, forming 

 key- rocks and divergent crevices. An instance 

 in point was seen in the diggings of Mr. 

 Meredith, in the N. E. qr. of Sec. 33, about 

 300 feet south of the old Wooley range, on 

 the summit of the ridge. 



A shaft was sunk on the main crevice which 

 continued without change for sixty feet from 

 the surface. At this point a hard key-rock, 

 as it is called, was encountered, on which 

 the crevice and ore sheets divided, one part 

 continuing vertical, and the other slanting 

 downward at an angle of about 45 for a 



distance of thirty feet. Here a vary hard and 

 smooth floor was found on which the sheet 

 was followed out by drifting, for a distance of 

 one hundred and thirty feet without reaching 

 the end. No appearance of openings was 

 observed. These diggings were struck about 

 six years ago (1870) and have produced since 

 then about 420,000 Ibs. 



SECTION OF THE MHRBDITH MINE. 



Rockville Diggings. 



There are here a number of east and west ranges with flat openings, which have been 

 worked with but little interruption since 1840, and now furnish employment to about 

 twenty miners. Mining is chiefly confined to the winter season. The following parties 

 are now operating here. 



Phillips & Walker. S. W. qr. of S. W. qr., Sec. 13, T..3, R. 3W. These parties 

 are working a new east and west range, discovered by them in the summer of 1874. 

 The ore is found at a depth of about 100 feet below the surface, in flat openings from 50 

 to 60 feet wide, whose length has not yet been ascertained. They have, however, been 

 worked to a distance of 300 feet. The lead ore is found in what is known here as the 



