322 GEOLOGY AND GOLD DEPOSITS OF THE CRIPPLE CREEK DISTRICT. 
No. 2, Republic, Mayflower, Le Clair, and Thurlow claims, and covers about 34 
acres. It is owned by the Mary McKinney Company, of Colorado Springs, incor¬ 
porated in 1892, and capitalized at $1,000,000. Up to the beginning of 1889 the 
mine was worked by lessees, the first shipment of ore being in 1893. Early in 
1899 the company began operations^ on its own account, and erected the present 
shaft house. The first dividend was declared in October of the same year. 
The mine has produced a large amount of ore and has undoubtedly been 
profitable to the company Statistics of production, however, are not obtainable. 
UNDERGROUND DEVELOPMENT. 
The main shaft, 609 feet deep, is on the Republic claim, about 1,000 feet 
from the south end of the property. There are four other smaller shafts, of which 
the only one now in use is the Burke and Fry shaft, in the northern part of the 
mine, operated b}^ lessees. 
There are five main levels, which at the shaft are approximately 135, 210, 
280, 380, and 485 feet below the surface. These extend through the Republic and 
Mary McKinney claims in a general north-northeast direction, practically from 
one end of the property to the other. In the southern part of the mine the drifts 
are of simple linear plan, following the Mary McKinney and Le Clair lodes, which 
intersect at a small angle. In the northern part of the mine, however, the work¬ 
ings, as may be seen from fig. 32, are more complex, owing to the less regular char¬ 
acter of the Assuring and to the existence of a number of so-called “flat veins,” 
some of which are shown in fig. 33. The Ophelia tunnel passes through the 
northern end of the mine, 15 or 20 feet above level 4. 
GEOLOGICAL FEATURES. 
The workings of the Mary McKinney mine are mainly in breccia and phonolite. 
Although on the surface the granite-breccia contact is less than 400 feet west of 
the shaft, it was seen at only one point in the mine, in a west crosscut on level 4, 
south of the shaft. It is here fairly distinct and seems to be about vertical. It 
is probably cut also in an old unused adit connecting with level 1. 
The main country rock of the mine from the south end to a point about 1,200 
feet north of the shaft is phonolite, varying in texture from the greenish aphanitic 
variety, common in the dikes and smaller intrusive masses of the district, to tra- 
chytic facies showing phenocrysts of feldspar and pyroxene. The form of this 
phonolitic mass can not be even approximately determined from existing workings. 
It does not appear to reach the surface, though it is the principal rock of all the 
levels from 1 down. The crosscut into the granite on level 4 shows breccia between 
the phonolite and the granite, but the contact between the phonolite and breccia 
is very obscure. In the northern part of the mine the contact is comparatively 
sharp and regular. It strikes nearly east and west and dips 85° S. On level 4 it 
has the appearance of an intrusive contact, but on level 3 this relation, if, as seems 
probable, it is the true one, is obscured by the abundance of phonolite fragments in 
the adjacent breccia. 
One of the most interesting geological features in the northern part of the 
mine is a sill, or recumbent dike, of trachydolerite, locally known as the Howard 
