Page 156 - The Geology and Ore Deposits of Sierra County, New Mexico - Bulletin 10

154 GEOLOGY AND ORE DEPOSITS OF SIERRA CO., N. M.
In places stope fill may have been further enhanced in value by the infiltration of fines from the richer parts of the vein during hand sorting in the stapes, where canvas or boards were not used. One estimate of commercial material remaining in this mine, using a 4-foot width of vein (although it is much wider in places) and 16 cubic feet to the ton as compared with 12 cubic feet in
place and 20 cubic feet when broken, is as follows :
Estimate of Ore Reserves of Rattlesnake Mine
Tons
Ore in place (in pillars and un- worked parts of vein) ----- 59,707 Stope fill --------------------- 99,615 Ore in surface dumps --------- 17,336
Value, per Ton
$8.00 5.00 3.38
Gross Value
$ 477,656 498,075 58,591
Total 176,658 $5.85 $1,034,322
Old shipment records show that 1 ton of hand-sorted ore worth $68 per ton was shipped direct for each 3 tons of $22 ore sent to the mill, making 4 tons of an average grade of $33.50. The part of the vein from which this shipping ore came did not average more than a foot in width. The above estimate of ore in place does not, according to the report from which the figures were obtained, include any probable ore in areas above the low- est level, even though development work has indicated the pres- ence of ore in some such areas, nor does it include any possible ore below the present workings. Such ore, if finally developed, might be expected to average about 4 feet in width and to assay $12 to $14 per ton, assuming the correctness of the figures sub- mitted above.
According to private reports seen by the writer the per-ton cost of mining was $1.04, milling $1.19, hauling $0.24, a total of $2.47. Assuming $2.50 as an average cost of working the ore and fill, thus neglecting all costs of developing new ore reserves, and taking an average of the old mill recovery figures of 75 per cent, there would be a local operating profit in treating the mine fill of $1.25 per ton or $125,000 ; for treating the ore in place $3.50 per ton, or a total of $210,000 ; and for dump ore there is an indicated profit of $15,000, making a total local operating profit on the above reserves of $350,000. Transportation costs to the railroad at Lake Valley when this mine was working were $4.00 per ton ; today they would be $1.70 to $2.00 per ton. Freight to El Paso is $1.00 per ton. In a mill of modern design a concentration ratio of 10 tons of ore into one ton of concen- trate may be safely assumed.
KATHERINE VEIN
The Katherine vein is east of the main Rattlesnake vein and
is considered to be a split from it near the Bobtail shaft. It has a strike of N. 42° E. A fault, which strikes northwest and passes through the Eureka shaft of the Snake vein, has offset