328 GEOLOGY AND GOLD DEPOSITS OF THE CRIPPLE CREEK DISTRICT. 
where stoped between levels 3 and 5 consists of a sharply distinct veinlet of fluorite, 
quartz, and calaverite rarely more than an inch in width. This is usually asso¬ 
ciated with a little parallel sheeting of the breccia, but the value of the ore lies 
almost wholly in the small veinlet, which in spite of its diminutive size is rich 
enough to stope. The calaverite occurs chiefly along the sides of the veinlet and 
and in the medial quartzose vugs. 
The main interest in the northern part of the mine centers in the occurrence 
of ore bodies at various intersections of lodes with each other and of lodes with the 
Howard dike. Such a body occurs just above level 4, where a triangular portion 
of the “basalt” bounded on the northwest b}” the Mary McKinney lode, on the 
northeast by the No. 4 cross lode, and on the south by the contact plane between 
the breccia and phonolite carried enough calaverite in the innumerable minute 
fissures or joints of the rock to constitute an important pay shoot. A similar 
though less extensive mineralization of the dike occurs between levels 3 and 5 along 
the intersection with the No. 2 lode. 
Another important pay shoot occurs at the Burke and Fry shaft on level 5> 
along the line of the No. 2 lode. This body of ore is about 250 feet in length and 
has a maximum width of about 40 feet. The ore does not extend more than 15 
or 20 feet above the level, but how far it goes below is not yet known. The ore 
body occurs where a number of fissures, including the No. 2, Work, No. 6, No. 3, 
and No. 5 flat veins intersect. In the vicinity of this intersection the breccia is 
elaboratelv fissured. In addition to the named sheeted zones, there is also a 
pronounced local sheeting with a dip of about 35° S., a system of fissures generally 
parallel with the No. 2 lode, and much irregular jointing. The ore occurs not only 
in the intersecting lodes, but in practically all of the immediately adjacent fissures, 
forming a body of irregular shape with no definite boundary separating it from the 
breccia country rock. The value lies in the fissures, in the form of calaverite 
associated with thin films of quartz and fluorite. 
The Work lode is of no economic importance in the Mary McKinney mine except 
at the intersection with the No. 2 lode. It is, however, a strong, prominent vein, 
locally showing over a foot of fluorite and quartz between well-defined walls. This 
vein is usually accompanied by parallel sheeting of the breccia. In some portions 
the filling is chiefly dark, compact fluorite, whence the name Black vein. Else¬ 
where the filling is chiefly quartz with abundant open vugs. This quartz is clear 
and vitreous, resembling that described in the Howard flat vein, in the Ophelia 
tunnel, and Anaconda mine. The Jackpot lode is also a well-defined sheeted zone, 
but contains only small bunches of ore at the intersection with the Mary McKinney 
lode. 
CHARACTER OF ORE. 
The principal gold-bearing mineral of the Mary McKinney mine is calaverite, 
which occurs associated with quartz, fluorite, dolomite, roscoelite, tetrahedrite, 
and pyrite. So far as observed the calaverite is found only in the fissures, never 
within the unfissured country rock. Pyrite, on the contrary, is widely disseminated 
through the country rock. In the breccia of the northern part of the mine some 
of the calaverite occurs with mere drusy films of quartz or fluorite in extremely 
