518 MINING IKDUSTET. 



During the latter half of 1868, when operations were resumed, there 

 were produced 3,942xVo ounces of amalgam, worth $88,379 82 in currency. 

 If the quantity of ore be assumed in about the same proportion to the pro- 

 duct as in the former case — that is, say, one ounce of amalgam per ton^ — we 

 have 3,942 tons, producing $22 42 per ton in currency. 



The costs during the same period were, for mining expense, $45,206 86, 

 and for teaming expense, $6,441 42 ; which, assuming the quantity to be as 

 above, are equal to $11 52 per ton of ore for mining, and $1 63 per ton for 

 hauling. Milling expenses during that year were a little more than counter- 

 balanced by the profits derived from working custom ores; the actual costs, 

 however, were not less than $20 per cord, or $2 66 per ton, making a- total 

 of $15 81 per ton, exclusive of office expense and interest. Judging from 

 the data given below concerning the operations of 1869, the number of tons 

 above given is too small. By increasing this number, the yield per ton and 

 the cost of working per ton will be correspondingly decreased. 



During the first half of 1869 there were produced 3,177 ounces of re- 

 torted amalgam, worth $65,755 94, in currency. The quantity of ore is stated 

 at 622| cords, equal to 4,670 tons. The average yield per cord is 5xV ounces 

 of retorted amalgam. During this period the mining expense was $37,833 80, 

 and the teaming expense $2,899 70. Accepting 4,670 as the number of tons 

 worked, we have a mining expense of $8 10; of teaming, 62 cents; and esti- 

 mating milling, as before, at $2 66, we have a total cost for the above items of 

 $11 38, and a yield per ton of $14 08 in currency. 



Briggs. — The Briggs Gold Mining Company's property adjoins the Black 

 Hawk on the east. The mine is 250 feet in length and opened by two shafts, 

 one of them 71 feet from the east line, the other 51 feet further west. Both 

 are sunk on what is considered the Gregory crevice, but the southeastern 

 branch of the vein, the Briggs, has been worked to a greater depth and yielded 

 a larger amount of ore than the Gregory. On the eastern end of this pro- 

 perty the two branches are near together at the surface, diverging, however, 

 slightly in depth. Horizontally, the branches are found to diverge between 

 the two shafts, the line of junction dipping westward, so that, as has been 

 already shown, at a depth of 300 feet the division of the vein into two parts 

 occurs on the Black Hawk property. 



