136 GEOLOGY AND GOLD DEPOSITS OF THE CRIPPLE CREEK DISTRICT. 
A favorite method of stoping is to break down the whole of the ore in place 
between two levels, leaving the loose rock to be drawn off through shoots as rapidly 
or slowly as may be required. This leaves the empty stope entirely unsupported. 
Sometimes the walls are partly secured by stulls while the ore is being drawn off. 
The ordinary half or three-fourths ton cars are used. The El Paso is the only mine 
in which 1-ton cars have been introduced and hoisted on cages. Buckets are also 
employed very extensively in the shafts and sometimes used to a depth of even 
1,000 feet, a practice which is not to be recommended. Practically all of the shafts 
are perpendicular. The hoisting is generally effected by steam; electric power is 
used in winzes and small shafts. The Portland is the only mine which has installed 
self-dumping 3-t.on skips into which the contents of the cars are directly charged at 
the various levels. At this mine the waste is disposed of into side-dumping cars 
taken to the dump by rope haulage. 
In treatment and sorting of the ore at the mines various plans have been 
adopted. The general occurrence of friable tellurides in cracks and fissures forms the 
principle upon which the sorting and separation is based. The fines are invariably 
much richer than the coarse stuff, and the separation of the two classes becomes of 
importance. The ore is usually broken on plank floors with canvas underneath to 
avoid loss of the fine material. A rough preliminary sorting is effected in the mine—- 
at least in places where wide stopes are being operated. The further treatment 
varies in the different mines. Very rich ore containing from 4 ounces upward is 
usually sacked and sent to the smelters. At the Portland mine the following 
process is adopted, the scheme being outlined in the eighth annual report of the 
company by Mr. Charles J. Moore, formerly its consulting engineer, as follows: 
Crude ore. 
Milling ore, Mill dirt, Waste, 
$15 to $60. $5 to $15. below $5. 
