1 873.] Colorado Gold Mines. 21 



year was about 400,* crushing about 100,000 tons, whose 

 average yield perton must have been between 10 and 12 dols., 

 for part of the annual production came from the No. 1 ore, 

 smelted by Prof. Hill. The absolute contents of these ores 

 was probably 35 dols. per ton of gold and silver, 3 per cent of 

 copper, worth say 1*50 dols. per unit, and the same per- 

 centage of lead, worth say 50 cents per unit. I attach some 

 value to the lead, inasmuch as, though the lead scattered 

 through the iron and copper pyrites is valueless, there are 

 lodes yielding massive galena, and others where the galena 

 might be separated from the other sulphurets, advanta- 

 geously both to the miner and the smelter. Therefore — 



Dollars. 



100,000 tons, containing 35 dols. in gold 



and silver, are worth 3,500,000 



300,000 units of copper, at even 1*50 



dols. per unit 450,000 



300,000 units of lead, at 50 cents per unit 150,000 



Absolute value of metals in the ore . . 4,100,000 

 Allow for loss in dressing, say 20 per cent 820,000 



3,280,000 

 Present yield with battery amalgamation 

 and smelting of No. I. ore only (ave- 

 rage of 2 years) 1,323,000 



Saving under altered system .... 1,957,000 



This saving would almost represent profits derived by 

 miner and smelter; for the cost of crushing and concentra- 

 tion, were battery amalgamation supplanted by simple con- 

 centration and smelting of the whole produce of the mines, 

 would be so much less than that of pulverising and amal- 

 gamating that this saving, added to the profit derived from 

 the smelting of copper ores, concentrated as they then would 

 be to 10 to 12 per cent, and purchased probably at 2*50 dols. 

 per unit, would pay for the cost of treatment. Of course 

 the miner would not receive from the smelter the full value 

 of the gold and silver, but he would receive a higher per- 

 centage of their value than he now does, and thus the 

 smelter and he would divide the increased profit between 

 them. 



As I shall show, the cost of mining and milling is now 



* Raymond, Report for 1870, p. 294. 



