ENDLicH.] GEOLOGY— FUTURE PEOSPECTS OF MINING EEGION. 291 



features of numerous veins, that practically their depth is inexhausti- 

 ble ; that they are what is popularly termed true fissure-veins, although 

 their yield of the precious metals may fluctuate. All observations of 

 strikes, &c,, have been given in the true, not magnetic, meridian, allow- 

 ing 15° deviation for the reduction. Local attraction is very strong at 

 times, and the best way of getting the true course was to locate the 

 lodes on a map prepared for field-use. 



■When first that mining-region became known, a great deal of gold was 

 obtained from the gulches, where it had accumulated for ages ; but, 

 although gulch-mining is still carried on to a small extent, practically 

 that source for obtaining the precious metal has ceased. It follows 

 necessarily that, with the decrease of the production of gulch-gold, 

 the mining industry will rise, provided the veins are sufficiently rich to 

 be remunerative. That this is the case is demonstrated by the fact 

 that quite a number of mines have been in operation now for several 

 consecutive years. Were it not that reported discoveries of new min- 

 ing-districts, more prolific than those occupied at the time, attracted 

 labor and capital, the development of these older regions would have 

 progressed much more rapidly. Nevertheless, it seems highly probable 

 to me that when labor will be cheaper, and competition reduces the 

 smelting-processes to their most economical form, the mines of a dis- 

 trict like the one under consideration will rank by far higher than at 

 present. 



Although not strictly within the limits that have been assigned to 

 these examinations, I wish to say a few words about the treatment of 

 the ores. Formerly, when a large proportion of ores could be classed 

 as surface-ores, the process of amalgamation returned very favorable 

 results ; but exj)erience has shown that either the ore from lower depths 

 is not so rich as that found nearer the surface, or there is a defect in 

 the process. It must be admitted that, as a rule, the lower ores will not 

 be quite so rich as those from the surface, because the particles of gold 

 that have weathered out may accumulate on the surface to some extent 

 and produce a higher average percentage of the metal. On the other 

 hand, the recognition and appreciation of this fact turns upon the ques- 

 tion. Is gold contained in the ore as a compound? An answer to this 

 would answer the other question. Significant remains the fact that, 

 while a number of mills and other amalgamation establishments have 

 failed and have been abandoned, the few smelting- works that have been 

 constructed upon and regulated by a reasonable basis, not attempting 

 to introduce processes that looked very well when regarded in the light 

 of a reminiscence of alchemistical experiments, have thus far been suc- 

 cessful in their treatment of ores. 



Through the kindness of Mr. Hill, of Black Hawk, I have been sup- 

 plied with a schedule of the prices he pays for ores delivered at his 

 smelting-works : Ores containing, per ton, 150, charges for smelting 

 $35, pays $15 ; ores containing, per ton, $100, charges for smelting $40, 

 pays $60 ; ores containing, per ton, $150, charges for smelting $45, pays 

 $105 ; ores containing, per ton, $200, charges for smelting $50, pays $150 ; 

 and, in addition to this, $1.50 for every per cent, of copper in 2,000 

 pounds. All the prices of this schedule are in currency. 



Since returning from the field, I have been informed that Mr. Hill has 

 erected quite extensive refining-works, and instead of sending his matter 

 to Swansea, England, as heretofore, it is refined there, and, according to 

 statements received, with very satisfactory results. 



Lately some concentration- works have been imt up in Colorado, partly 

 not quite completed, partly still in their infancy, so that but little can 



