GOLD MINING IN COLOEADO. 577 



Treatment of the fiest-class or smelting ores. — The works of the 

 Boston and Colorado Gold Smelting Company are situated in Gregory Gulch 

 below the town of Black Hawk, a half mile below the junction of Chase and 

 Gregory Gulches. The business of this concern consists in purchasing the 

 selected ores of higher grade from the various mines, as well as, also, the 

 dressed tailings from the mills, and treating them by the process of smelting 

 for the extraction of the gold, silver, and copper contained. By the methods 

 thus far introduced at the works these metals are obtained in the form of 

 "matt," which consists mainly of the sulphide of copper with sulphide of iron, 

 containing, when concentrated to the required standard, from 50 to GO per 

 cent, of metallic copper, and having combined with it the gold and silver in 

 varying proportions, but commonly about 40 or 50 ounces of fine gold and 

 from 100 to 400 ounces of fine silver to the ton of matt. This crude metal, 

 or matt, is at present shipped in that form to Swansea for refinement or part- 

 ing of the several metals, as the necessary separation works have not yet been 

 provided at the Colorado establishment. The works for the treatment of the 

 matt, that is the ultimate separation of the metals, not only involve a large out- 

 lay of capital, but would, for economical operation, require a much larger supply 

 of matt than could be furnished from the single smelting furnace at first provided. 

 The company, therefore, deferred the construction of separation works until the 

 business should be established upon a sufficiently broad and permanent basis. 

 Within a year or little more the smelting capacity of the works has been 

 doubled, additional furnaces having been built, and it is understood that the 

 necessary works for the treatment of the matt will presently be added ; when 

 the whole process will be performed at the company's establishment at Black 

 Hawk. 



The metallurgical process, therefore, so far as it is carried at present in 

 Colorado, is confined to the preliminary concentration of the metals; that is, 

 the gold, silver, and copper that may be distributed through 10, 20, or 30 tons 

 of ore, or tailings, are brought together by smelting into one ton of matt, or 

 crude metal ; the final separation and extraction of the several metals being 

 done elsewhere by methods not yet introduced into the Territory. 



The process employed for the production of the matt is not essentially 



difierent from that in use, during many years, in Europe, whence it was 

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