420 MINING INDUSTRY. 



openings. Again, the ore may entirely, or in part, have ascended the main 

 channel until, coming in contact with the overlying and impenetrable shale, 

 it may then have been forced out laterally, forming a stratum of metal- 

 bearing matter between the limestone and shale, and, where meeting with 

 openings and depressions in the lower rock, penetrating through them, filling 

 them from above. 



At a later period the overlying shale and ore stratum has been eroded, 

 leaving the openings and chambers, filled with ore, exposed, without any 

 visible connection with each other at the surface. 



This latter hypothesis appears all the more probable when we are able to 

 see the shale, with the quartz and ore-bearing material below, still in place 

 upon the north end of Treasure Hill. It may be remarked that what has 

 been said of the geological position of the ore-bodies upon Treasure Hill ap- 

 plies to the deposits on the Base Metal Range. In general these latter bodies 

 are far less rich in silver and carry more lead and copper. Those which have 

 been most developed are rich, argentiferous lead ores, and occur most fre- 

 quently at a lower stratigraphical position than the purer and richer chloride 

 ores of Treasure HiU, 



The following analysis of rich White Pine ore, by Mr. O. J). Allen, serves 

 to show its chemical character. The specimens from which the analysis was 

 made were taken from the Aurora South claim on the day of the writer's 

 visit; they were carefully selected, and contain both the gray and green 

 chloride of silver : 



Gangue, nearly pure quartz 84. 005 



Sesquioxide of iron 390 



Alumina 068 



Lime , i, 008 



Lead 2.186 



Copper 962 



Silver 5,685 



^I'senic. 548 



CWorine i. 641 



96. 493 



