EXDLicH.] COPPER, ZINC, AND LEAD. 121 



tellurides of gold and silver occur there that greatly increase the value 

 of the ore. Settlements have sprung up with the rapidity usually ob- 

 served in new mining countries, and a region that, but a few years ago, 

 was a wilderness, to-day shows ample evidence of the enterprise and 

 industry of the pioneer miner. 



All the ore-bearing veins of the San Juan region, as well as those of 

 the Summit district, lie within the trachorheitic area. We have in this 

 instance veins that, in their physical and mineralogical character, can- 

 not be distinguished from those of the older formations, occurring in 

 volcanic rocks of Tertiary age. The unusually rugged and broken con- 

 figuration of the country facilitates mining operations. Not unfre- 

 quently metalliferous veins may be traced for several hundred feet of ver- 

 tical distance on the steep, rocky slope of some mountains, or in the walls 

 of a caQon, Obviously such conditions must be favorable to the miner, 

 assuring him at once of the presence of his ore for a certain distance, and 

 pointing out to him a ready method of extraction. Up to the present 

 lime the development of tho San Juan mines has been retarded by the 

 want of available capital. The individual miner, however industrious 

 he may be, cannot by his own physical labor properly develop a mine. 



A word may be said with reference to the treatment of Colorado ores. 

 Naturally, the first method employed was that of crushing the ore and 

 saving the gold by raw amalgamation. This process is the one Requiring 

 the minimum of preparation, one that every man of average intelli- 

 gence can readily become familiar with, and furnishes to the miner his 

 weekly or monthly product in the shape of bullion. So long as surface- 

 ores — i. e., of gold — were the only ones treated in this way, ic answered 

 very well. As soon as the undecomposed ore was reached, the results 

 were no longer found to be satisfactory. In that case the only reasona- 

 ble method is smelting. Thereby the gold, that otherwise will often go 

 into the tailings and perhaps be lost altogether, can be saved. The 

 sooner this fact is fully appreciated, and the more the smelting processes 

 are brought into harmony with established laws of chemistry (which is 

 not always done), the better will the miner find himself repaid for his 

 hard and dangerous work. A number of good smelting- works have been 

 established in Colorado, and they are fully able to take charge of the 

 ore that may be furnished them, with advantage to the smelter and 

 profit to the miner. 



Small placers occur at several places in the districts I have examined. 

 Some of them are worked at present ; others have lain idle for years, 

 and still others areexhausted. In and near Taylor Eiver Park, in Grey- 

 back Gulch, on the North Fork of Eio Alamosa, and elsewhere, a little 

 work is carried on. 



COPPER, ZINC, AND LEAD. 



These metals are gained in the extraction of gold and silver ores. 

 They are so abundant, associating with the more precious, that they can 

 be regarded only as a secondary consideration. Some of the smelting- 

 works devote either a poition or their entire force to their extraction. 

 In that case the metals are mostly obtained from low-grade gold and 

 silver ores. Uranium, occurring in pitchblende, was mined in the Wood 

 mine, near Nevada. The yield was satisfactory. At present the mine 

 lies idle, but it is to be hoped, if only for the sake of mineralogists, that 

 work may ere long be resumed. With mineralogical " treasures'' of such 

 a nature Colorado is well supplied ; less, perhaps, as regards number of 

 species than so far as size and beauty of those occurring are concerned. 



