138 GEOLOGY AND GOLD DEPOSITS OF THE CRIPPLE CREEK DISTRICT. 
SAMPLING. 
The sampler, in the western mining regions, is the recognized middleman 
between mine and reduction works. His services have been found particularly 
acceptable at Cripple Creek on account of the richness of the ore and the corre¬ 
sponding difficulty of obtaining an agreement between smelter and miner. The 
leasing system in vogue has also helped the sampling works by multiplying small 
parcels of ore which must be separately handled. A modern sampling mill is 
quite a complicated affair, especially where rich ores render extra care necessary, 
and it is sometimes arranged to run almost automatically. Even large mines use 
the services of samplers, the Portland and the Woods Investment Company being 
the only ones possessing mills of this kind for their own exclusive use. The 
charges, not including freight, run from 60 cents to $1 per ton. The principal 
sampling mills working at present in the district are the Cripple Creek, the Rio 
Grande, the Eagle, and the Taylor & Brunton. 
The last, situated in the gap between Bull Cliff and Big Bull Mountain, is 
the most modern plant and a brief description of its process may be of interest. 
The ore is shoveled from the car into a bin from which it goes to crusher and coarse 
rolls (42 inches). An automatic elevator carries it to the top of the building to 
36-inch rolls, below which an automatic sampling machine, by alternately deflect¬ 
ing the stream of crushed rock, cuts out 20 per cent of the total material. This 
20 per cent goes to 27-inch rolls, below which a second sampling machine cuts out 
20 per cent, the operation being repeated underneath the third (20-inch) rolls. All 
of the rolls have automatic feeders. The total sample now amounts to 1 per cent 
of the total amount and has been crushed to about one-sixteenth of an inch in 
average size. If necessary, in large lots of ore comprising several cars, this is 
further reduced by hand, with the implement known as a “split shovel,” to about 
0.08 per cent of the original lot of ore. The sample, which now weighs from 20 to 
50 pounds, is dried and crushed fine in a rotary grinder and further reduced by 
means of the “split box” to about 30 ounces. The final pulverizing is accom¬ 
plished by means of the bucking board and a 110-mesh screen. A smaller splitter 
divides it into four parts which make the final samples. One of these is assayed 
at the sampling works, another is sent to the shipper, while two are held in reserve 
in case of disagreement between the sampler and the smelter. 
PROCESSES OF REDUCTION.' 
The history of the development of the present processes of reduction for the 
Cripple Creek gold ores is in many respects of great interest.® Stamp milling, long 
the recognized mode of treatment of gold quartz, was first tried. During 1892 and 
1893 ten stamp mills of the Gilpin County type with slow drop and light stamps 
were erected, aggregating 270 stamps, the largest being the Rosebud and the Gold 
and Globe mills, having, respectively, 60 and 40 stamps, both situated along Cripple 
Creek below the town. A short trial sufficed to demonstrate their inefficiency to 
deal with the free gold, on account of difficulties of amalgamation due to a tarnish 
supposed to be tellurite of iron. Percussion tables and blankets were introduced 
a For a full account of the early attempts to reduce the ores see Rickard, T. A., The Cripple Creek gold field: Trans. Inst. 
Min. and Metallurgy, vol. 8, London, 1899. 
