562 



MINING INDUSTEY. 



Original assay value 

 of ore in coin per 

 ton. 



Yield obtained in 

 coin per ton. 



Per cent. 



Assay value of tail- 

 ings in coin per 

 ton. 



Per cent. 



$17 31 

 20 97 



$6 68 

 6 86 



38.58 

 32.70 



$10 71 

 10 92 



61.87 

 52.07 



The average value of the tailings, produced by the mills of the district, 

 is variously estimated ; but they are generally believed, by those who have 

 given much attention to the subject, to contain about $10 or $12 per ton, in 

 gold, and $2 or $3 per ton, in silver. 



The following statements present the results of a number of assays of 

 raw tailings, or such as have not been subjected to any method of concen- 

 tration. 



The first of the two series of assays, given below, was furnished to the 

 writer by Professor N. P. Hill, manager of the Boston and Colorado Smelt- 

 ing "Works. These assays represent a better quality of tailings than the general 

 average throughout the district. Some of them were old, produced years ago, 

 when the richest ores, which are now smelted, were crushed and amalgamated 

 in stamp-mills. They are given here to show the value of the better class of 

 tailings ; while the second series of assays, made by Mr. A. von Schulz, is 

 believed to represent more correctly the average quality of tailings produced 

 at the present time : 



statement of Assays of Raw Tailings from the records of the Boston and Colorado Smelting Works. 





Ounces of fine 

 gold per ton 

 of 2,000 lbs. 



•a 

 ■" 



I 



Ounces of fine 

 silver per ton 

 of 2,000 lbs. 



1h 



> 



■« s. 

 ° H 



Total assay value 

 of tailings per 

 ton. 



Samples of old tailings of Bobtail ore ------ 



Do. do. _----- 



Samples of old tailings of Bobtail ore, (Sensenderfer) 

 Samples of more recent taUings— Burroughs lode - 

 Do. do. do. 

 Do. do. do. 

 Samples of more recent tailings — Gregory lode - - 

 Samples of more recent tailings from Kimber's Mill 



Average value of eight samples ------ 



1.29 



•97 



1. 21 



1.07 



1.28 



.96 



.96 



.64 



$26 66 

 20 04 



25 01 

 22 II 



26 45 

 19 84 

 19 84 

 13 23 



S.18 



5.34 

 4.13 



3.31 



1.92 



3.87 

 4.96 

 5.83 



$6 68 

 6 90 

 S 32 



4 27 

 2 47 



5 40 



6 38 



7 51 



$33 34 

 26 94 



30 33 

 26 38 

 28 92 



25 24 



26 22 

 20 74 



- - 



$21 6s 



- - 



$561 



$27 26 



