MINES— POTOSI DISTRICT. 



699, 



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

 ally found in the other mining districts. 



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 are 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 aU, which 

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

 smaller crevices not sufiiciently important to constitute ranges by themselves. 



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

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



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

 tlie 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 

 p^^^i district, by which, they seem to split up 

 in the lower beds of the limestone, forming 

 key-roqks 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 wliioh 



continued without change for sixty feet from 



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



Fig. 14. 



Seotiok of the Mhhbdith Mine. 



J as it is called, was encountered, on which 

 '4]~^_- the crevice and ore sheets divided, one part 

 continuing vertical, and the other slanting 

 downwai'd at an angle of about 45° for a 

 distance of tliirty 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 vrithout 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 lbs. 



Rockville Diggings. 



There are here a number of east and west ranges with flat openings, wliieh 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. 3 W. 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 flatopenings from 50 

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

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



