442 GEOLOGY AND GOLD DEPOSITS OF THE CRIPPLE CREEK DISTRICT. 
equally distinct on different levels and there is often much minor Assuring of the 
country rock between them. It is therefore by no means certain that the same 
number is always applied to the same lode on different levels. For example, the No. 
4 Captain vein on one level may correspond to what is termed the “ No. 5 ” Captain 
vein on another. The designations of these lodes are frequently changed as develop¬ 
ment throws new light on their relations. The easternmost productive lode of the 
series, the No. 9 Captain vein, presents an exception to the general strike and dip 
of the other lodes of the Captain system and is associated with a phonolite dike. 
This lode strikes a little east of north and dips west at about 80°. It probably 
should not strictly be included within the Captain system. 
The Captain veins, while economically of great importance, as will be later 
shown, are not persistent. They have rarely been followed horizontally for more 
than 300 feet. First attaining importance between the 220-foot and the 350-foot 
level, the known lodes of the system become indistinct and of comparatively little 
value below the 600-foot level, though some ore occurs in them above the 700-foot 
level. 
North of the great ore zone in which occur the Lee, Hidden Treasure, and 
Captain veins is an extensive territory now being exploited from the No. 3 shaft. 
Thus far no ore bodies of importance have been discovered in this part of the 
Portland workings proper, though ore was formerly shipped from the old workings 
of the Colorado City and Hawkeye shafts nearer the surface. About 225 feet 
southwest of the No. 3 shaft, however, is the Lost Anna vein, striking northwest 
and southeast and dipping steeply to the northeast. Tins lode, which lies in the 
general line of the Captain veins, is known on the adit and 1,000-foot levels. While 
apparently not of much importance on the upper level, it promises well below the 
1,000-foot level. 
CHARACTER OF ORE. 
Probably no one mine in the Cripple Creek district has during its history pro¬ 
duced more varied types of ore than the Portland. All the unoxidized ores, 
however, are alike in owing their value to the presence of a telluride of gold, which 
seems to be almost invariably calaverite, though the occurrence of sylvanite has 
been reported by Rickard . h This telluride is rarely found in well-formed crystals and 
is frequently present in particles so minute as to be invisible to the naked eye. 
The chief contrast as regards texture and general mineralogieal association 
of the ores is to be found between those occurring in granite, on the one hand, and 
those found in breccia or phonolite, on the other. 
The ores in the granite are of distinctly metasomatic origin. The alteration 
of the country rock is always more or less closely related to Assuring, though the 
Assures are in some cases microscopic. The change from altered to unaltered rock, 
while never sharp, may take place within a distance of a few inches. The most 
striking characteristic of the altered rock is a porous texture and a loss of more or 
less of the reddish tint of the unaltered granite. Closer examination shows that 
while the original porphyritic aggregates of pink microcline may remain, the rest 
of the rock, consisting originally of microcline, oligoclase, quartz, and biotite, may 
a Rickard, T. A., The Cripple Creek gold field: Inst. Hin. and Met., London, vol. 8, 1899. 
