GOLD MINING IN COLORADO. 



563 



Statement of Assays of Raw Tailings, made by Mr. A. von Schuh. 





Ounces of fine 

 gold per ton 

 of 2,ooo lbs. 



2 



fll « 



I 



Ounces of fine 

 silver per ton 

 of 2,000 lbs. 



> 



-or 



3 P. 



Total assay value 

 of tailings per 

 ton. 





0.24 

 1.70 

 0.73 

 0.37 



Traces. 



Traces. 



Traces. 



Traces. 



Traces. 

 0.25 



$4 96 



35 13 



15 08 



764 



5 '7 



3-64 

 2.91 

 0.8s 

 1.70 



7 29 

 1. 21 

 I. IS 

 1.45 



2.IO 



%A 73 

 4 73 

 3 78 



1 10 



2 21 

 9 47 

 I 57 

 I 50 



1 88 



2 73 



I9 69 

 39 86 

 18 86 



874 

 2 21 



9 47 

 I 57 

 I 50 

 I 83 



7 90 









5 --- - 



6 ......... 









Average value of ten samples ...... 



- - 



?6 80 



- - 



?3 37 



§10 17 



Assuming that the tailings contain, on the average, $11 per ton, in gold, 

 disregarding the silver, and that the value of the gold obtained by milling is 

 $13 50 per ton, it appears that 55 per cent, of the gold in the ore is extracted by 

 the crushing and amalgamating process. To this, in order to ascertain the total 

 percentage of value obtained from the ore, should be added the product sub- 

 sequently derived from v^orking the tailings ; and if, as may appear from what 

 follows, this latter item amounts to 15 per cent, of the original value of the 

 gold, the total percentage extracted in the stamp mill may be placed at about 

 70 per cent. 



Treatment of the Residues, or Tailings. — It has been already shown 

 that after the ore, crushed by the stamps, has run over the amalgamated copper- 

 plates of the tables, it is variously treated in dilBTerent mills. In some it is 

 allowed to pass away in the tail-race without further attention ; in others it is 

 collected outside in dams and worked over by some simple methods of con- 

 centration. In many mills the tailing stream passes first over blanket sluices ; 

 the product of the blanket washings is then either ground and amalgamated 

 in Bartola pans or sold at the Smelting Works; while the great mass 

 of the tailings, having passed over the blankets, is subjected to still further 

 processes of concentration. In one or two mills Eittinger tables are used. 

 The dressed tailings, or the products of all these various methods of con- 

 centration, are, in most cases, finally sold at the Smelting Works, where 



