396 MINING INDUSTET. 



five miles north of Belmont. The section No. 5 on Plate XXVI gives a pro- 

 file of Highbridge Hill and the granite hill southwest of it, on a true scale. 

 The section is made on a line north 58° east. The quartzites exposed here 

 are probably the product of a local metamorphism, and do not seem to corre- 

 spond to the quartzites of Summit Canon in the Toyabe Range. 



Mining Developments in Philadelphia District. — The town of Bel- 

 mont is the center of a mining region of considerable importance, situated 85 

 or 90 miles from Austin, in a south-southeasterly direction. It is in the 

 "Smoky Range" of mountains, next east of the Toyabe, separated from the 

 latter by Smoky Valley. The district of most importance, judging by devel- 

 opments thus far made, is called the ''Philadelphia," or, sometimes, the "Sil- 

 ver Bend." It is in this district that the town of Belmont is located; and the 

 first important discoveries of silver-bearing lodes, in this vicinity, were made 

 near the site of that town in 1865. A small spur of the main range branches 

 off here to the southeast, and it is on the eastern slope of this spur that the 

 principal mining developments have been made. The best developed and 

 most promising veins are inclosed within a belt of metamorphic rocks, resting 

 on granite, which here forms the central portion of the range. These meta- 

 morphic rocks, where in contact with the granite, are frequently highly al- 

 tered, and may come under the general name of quartzite ; while, a little more 

 remote from the granite, further to the eastward, and overlying the quartzite, 

 is a belt of slates, striking nearly north and south, or north a little westerly, 

 and dipping to the eastward, from 30° to 50°. This belt of slate is probably 

 not less than a half or three-fourths of a mile in width, measured from west 

 to east, and is the outcropping rock of the hillside, from its contact with the 

 quartzite or granite down to where the slope merges into the plain of Monitor 

 Valley. The ledge, or vein, on which the largest amount of work has been 

 expended, and by reason of which the district has become widely known, is 

 the Highbridge or Transylvania. It is inclosed within the slates, conforma- 

 bly with them, having a course north 15° west, true, and dipping to the east- 

 ward generally, at an angle of about 30°, but sometimes much steeper, espe- 

 cially where the ground has been much disturbed, as in the Belmont and 

 Combination mines, where the dip varies between 60° and 90°. The out- 

 crop has been traced, for a distance of many hundred feet, along the side of 



