8 
GEOLOGY AND GOLD DEPOSITS OF THE CRIPPLE CREEK DISTRICT. 
CHAPTER X.-THE ORE SHOOTS. 
As a rule the ore in the veins occurs as well-defined shoots similar to those of 
other gold veins; their limit in depth is ordinarily as well marked as their extent 
in a horizontal direction. In discussing the shoots the terms pitch length, stope 
length, breadth, and width or thickness are adopted and defined. 
The shoots are generally tabular, elongated bodies dipping at steep angles from 
the horizontal on the plane of the vein. The width varies from a few inches to 50 
feet, 4 to 5 feet being a common size. The stope length in an ordinary shoot varies , 
from 50 to 300 feet, and in rare cases attains 2,000 feet. The pitch is steep, ranging 
from 45° to 90° and is generally northward. An average of the pitch length in the 
large shoots would probably he 500 feet, but in a few shoots this dimension attains 
1,500 feet, and in others the total length of the shoot has not yet been ascertained. 
While the outline is sometimes equidimensional, or again wholly irregular, elongated 
forms with ratio between pitch length and breadth of from 14:1 to 5:1 prevail. 
When one shoot ceases in depth, another may be found below it upon the same or 
adjoining fissure. 
Absolute and truncated pitch lengths are distinguished. In the latter case 
the upper part of the shoot has been removed by erosion. 
The influence of countrv rock is very slight, as excellent shoots occur in granite, 
gneiss, breccia, latite-phonolite, phonolite, sj^enite, and basic dikes. Breccia is, on 
the whole, the most favorable rock on account of its porosity. The smaller ore 
shoots are very commonly found at intersections of fissures or fissure systems, but 
tins factor is by no means the only one nor the most important one. The largest 
shoots are entirely independent of intersections. 
There is no decrease in the value of the ore per ton in depth, but the quantity 
of ore available is distinctly less below the 1,000-foot level, irrespective of the eleva¬ 
tion of the surface. Difficulties of exploration and development may to some extent 
account for this, but another influencing factor is that in many cases the fissure 
system is less well developed in depth. In addition to this explanation it is likely 
that for reasons related to temperature and solubility precipitation of ore took place 
more abundantly nearer to the surface. 
CHAPTER XI.-GENESIS OF THE DEPOSITS AND PRACTICAL CONCLUSIONS. 
Or igin of th e ores .—The wa ters which deposit ed the Cripple Creek veins were hot 
alkaline solutions which contained the following compounds and ions either free or 
in various combinations: Si0 2 , C0 2 , Ii 2 S, C0 3 , S0 4 , S, Cl, F, Fe, Sb, Mo, V, W, Te, 
Au, Ag, Cu, Zn, Pb, Ba, Sr, Ca, Mg, Xa, K. We believe that at least some of the 
Si0 2 , S0 4 , Cl, Fe, Ba, Sr, Ca, Mg, Na, and K are derived from the volcanic rocks by 
leaching of waters, while the remaining metals, as well asC0 2 , II 2 S, S, and some SiO, 
and Cl, were more probably separated from intrusive cooling magmas at considerable 
depth and brought up as solutions in magmatic water given off in the same manner. 
It is concluded that the formation of the veins took place shortly after the intru¬ 
sion of the last basic dike. The temperature at the time of deposition was high, 
but the critical temperature of water was probably not exceeded. It is shown that 
the igneous rocks contain primary water and the conclusion is drawn that the magna 
