Conundrum Mine, Cripple Creek Mining District, Teller County, Colorado, USAi

Regional Level Types
Conundrum Mine	Mine
Cripple Creek Mining District	Mining District
Teller County	County
Colorado	State
USA	Country

The ore of the Conundrum lode consists of mineralized "basalt." The rock is traversed by numerous narrow fissures, sometimes reticulating, but usually showing general parallelism with the dike walls. These little fissures are filled or partly filled, sometimes with purple fluorite, sometimes with quartz, and sometimes with both minerals together, giving the rock a banded appearance. These gangue minerals are not always confined to the fissures, but sometimes permeate the altered basalt between the distinct fractures.

As seen under the microscope, the "basalt" between the veinlets is thickly sprinkled with n1inute pyritohedral crystals of pyrite and with granules of secondary quartz. These lie in an exceedingly fine-grained and obscurely crystalline aggregate of uncertain composition. It appears to be partly quartz, partly feldspar, and partly some isotropic material, but the texture of the material is too fine for the microscopical determination of its constituents. It reveals no trace of the original igneous texture of the rock.

The gold occurs as calaverite associated with the quartz and fluorite and with pyrite. The ore, however, is often oxidized even below level 9 of the Midget or level 5 of the Conundrum, and the calaverite changed to native gold. Little specks of galena and sphalerite are common in the Conundrum dike, usually accompanying the gold ore. These minerals appear to have been deposited at least in part by replacement of the basalt and sometimes form bunches or lenses several feet long and 5 or 6 inches in thickness. This galena and sphalerite ore frequently contains 2 or 3 ounces of gold and about the same quantity of silver per ton. Galena and sphalerite are not confined to the Conundrum lode, but occur also in the Midget mine in the Bonanza King lode as lenticular masses a foot or so in thickness, replacing fissured gneiss.

The ore in gneiss in the northern part of level 6 of the Conundrum consists of calaverite, often beautifully crystallized, occurring in the vugs of quartz fluorite veinlets.