28 Colorado Gold Mines. [January, 



loss of silver in the slag will be so great as to reduce notably 

 the value of the silver. 



The probable cost of treating will, therefore, be — 



Dollars. 



Mining and hauling 50 tons at 6 dols. per ton 300 

 Handpicking and concentrating 50 tons at 

 2 dols. 100 



400 

 Value of gold and silver in the concentrate — 



Dollars. 



10 tons of concentrate containing 40 ozs. 



of gold 800 



10 tons of concentrate containing 60 units 



of copper 300 



1100 



The smelter should pay for ore containing 4 ozs. of gold, 

 6 per cent of copper, and probably 20 to 40 ozs. of silver, 

 at least 60 per cent of the value of the gold and 50 per cent 

 of the value of the copper. 



Therefore the receipts of the miner would be — 



Dollars. 



60 per cent of the value of 40 ozs. of gold . 480 

 50 per cent of the value of the copper . . . 150 



630 

 And as the cost of producing and concen- 

 trating would be 400 



The profit on 50 tons of 1 oz. gold ore would be 230 

 Or 4*60 dols. per ton. 



This calculation supposes that there is no No. 1 ore in 

 the vein stuff. As the custom mills charge only 3*84 dols. 

 for stamping and amalgamating a ton of ore, the allowance 

 of 2*oo dols. for crushing and concentrating is ample. 

 Moreover, the smelting would doubtless be done more 

 cheaply were there vigorous competition. But this cannot 

 be looked for till smelters can count with certainty on a 

 steady and abundant supply of suitable ore, which will only 

 be forthcoming when the whole produce of the mines 

 passes through their hands, and not the No. 1 ore only. 



From mines now open 1000 tons a day of 20-dollar ore 

 could be at once produced ; and there are second class mines 

 innumerable which under existing modes of treatment are 



