208 GEOLOGY AND GOLD DEPOSITS OF THE CRIPPLE CREEK DISTRICT. 
In 8 of the 60 cases the shoot extended from the surface to a depth of 1,000 
feet, or a little more, and ended. Further development to about 1,500 feet failed 
to find new shoots of any importance, though small pockets were often discovered. 
In 6 of these 8 cases the ratio of vertical to horizontal extent varies from 3:1 to 
5:1, and the shoots usually pitch northward at angles of 60° to nearly 90° from 
the horizontal. In the remaining 2 cases the shoots have about the same horizon¬ 
tal as vertical extent. The maximum horizontal length is 1,300 feet, while 400 is 
much more common. In 2 of the 60 cases the pay shoot is 1,500 to 2,000 feet 
long, maximum depths of 600 and 1,000 feet having been attained and the bottom 
level being still in ore. In 13 of the 60 cases the shoot began over 200 feet below 
the surface; in 8 of these the bottom of the shoot has been reached, while in 5 the 
lowest level is still in ore. Steeply dipping, irregular elongated forms prevail. 
Many of this group of 13 represent veins parallel and close to those on which pay 
shoots outcropping at the surface were found. 
These statements will give an idea of the form of the shoots. Of course, in 
the case of shoots reaching the surface, a certain part has .probably been removed 
by erosion. Judging from the shoots which distinctly began below the surface, 
the normal form of the ore bodies is elongated, vertical, or pitching sharply north¬ 
ward, the ratio of vertical to horizontal extension varying from 11:1 to 5:1. Some 
of these shoots are, however, of about equal dimensions, vertically and horizontally, 
while in a few the horizontal dimension is the greater. 
RELATION TO COUNTRY ROCK. 
In general the influence of country rock on the ore is ver}^ slight, and the causes 
governing the variations which may be detected are more apt to be due to physical 
differences relating to the 
Assuring in the various kinds 
of rock than to any chem¬ 
ical characteristics influenc¬ 
ing the ore deposition. Ore 
shoots occur in all of the 
various rocks cut by the 
vein, granitic as well as pho- 
nolitic. The best ore shoots 
are found in breccia, and 
this is probably due to its 
greater permeability and the 
greater width of Assuring in 
this rock. Very large ore 
shoots are, however, also 
inclosed by latite-phonolite 
and syenite, as well as by 
granite. As instances of the 
latter may be cited the gran¬ 
ite slopes in the Ajax, Portland, and Gold Coin mines, while the very important ore 
shoots of the Vindicator mine are almost exclusively contained in latite-phonolite. 
Fig. 15.—Cross section and longitudinal section of pay shoot in Prince Albert 
mine, showing its relation to phonolite sheet. 
