Coulogue Mine (Conlogue Mine; Walker Mines; Pioneer Shaft; Walker Diggings), Miller County, Missouri, USAi

Regional Level Types
Coulogue Mine (Conlogue Mine; Walker Mines; Pioneer Shaft; Walker Diggings)	Mine
Miller County	County
Missouri	State
USA	Country

Coulogue Mine (Conlogue Mine; Walker Mines; Pioneer Shaft; Walker Diggings), Central Missouri District, Missouri, USA

This mine is situated in Miller county. Though the yield has not been very large, it is an excellent example of the so-called “circle" deposits of the Central district. It is situated in the NW. 1/4 of section 5, township 41 N., 14 W. More work has been done here, and greater quantities of ore obtained, than at any other mine in Miller county. A large amount of shallow surface ore was found, as is attested by the innumerable pits which cover the hill-sides .

Chief interest attaches itself to the large open pit or conical chimney at the Ploneer shaft. The galena, as seen in undisturbed pillars, is firmly imbedded in calcite or barite lining cavities; in the breccia, however, it is said to have been loose, and the whole mass was excavated with pick and shovel. Sheets of barite were seen attached to the wall of the chamber, and galena is said to have been found in similar sheets, both attached to the surfaces and penetrating crevices in the wall and floor. Much of the barite occurs in crystalline masses, clear and glossy, like calcite, with rhombohedral cleavage and apparently pseudomorphous after the latter mineral.

This deposit was examined by the Geological Survey in 1873, when it was being worked, and is described by Schmidt as of circular shape, 30 to 40 feet in diameter and increasing in width with depth. The upper part was filled with red tallow clay; the lower part with masses of broken limestone, altered and softened, though angular, with broken sheets of galens and barite between. Seams of galena entended into the wall-rock in places and each were followed as much as 40 feet. Such seams also extended below the bottom of the shaft, but the enclosing rock became harder. Copper pyrite and malachite were found with the barite. Galena was always deposited on the limestone while the barite filled the remaining space, sometimes in fine crystals. The whole mixture contained from 5 to 10 per cent of galena. About 500 tons were estimated to have been mined here up to May, 1874.

Recently, a tunnel has been driven into the hill-side through the magnesian limestone country rock to the circle or central pit, with the idea of draining the latter and of reaching a large body of ore which was commonly belleved to still remain. It followed an ill defined vertical crevice, with lens like expansions, containing galena and barite. These lenses were, in cross section, a foot or so long and about 6 inches wide; they were also found between the horizontal beds of the wall-rock.

No faulting movement has taken place along the vertical crevice. The galena was also found in thin sheets. In all such cases, however, it is in the solid undecomposed rock, with no clay, though barite and calcite generally accompany it. The magnesian limestone is of course, open texture. Chert is imbedded, in nodules and lenticular layers.