Clark Mine, Crawford County, Missouri, USAi

Regional Level Types
Clark Mine	Mine
Crawford County	County
Missouri	State
USA	Country

This mine is located two miles northeast of Steelville and is situated upon the west face of the point of a hill projecting southeast from a high ridge. Like the Griffith mine, it is marked by a well defined sink structure. The area of the sink is shown by a rim of pitching Roubidoux sandstone, encircling it on three sides; the larger diameter extending northeast-southwest. The rim is not exposed for a short distance across the south end of the sink. Within this area one open cut, two shafts, and several shallow pits have been sunk.

The open cut, which is about 100 feet long, 40 feet wide, and 10 feet deep, was made on the north end of the rim where the latter crosses the highest point of the hill. Considerable soft red ore has been mined from this cut. The ore was found in a layer 12 inches or more thick between heavy beds of quartzitic chert and sandstone which dip about 25° toward the center of the sink.

A shallow pit located about 200 feet southeast of the cut exposes the cast rim of the sink but shows very little ore. A 70 foot pit, 30 feet east of the shallow pit and just outside of the rim of the sink, shows only ocherous, decomposed cotton rock and a soft, silicious clay that may represent decomposed chert and limestone. A 102 foot shaft, located about 100 feet southwest of the 70 foot pit, and well within the area of the sink, shows, throughout its depth, decomposed chert and quartzitic sandstone enclosing occasional thin seams of ore. The best seam of ore occurs at a depth of 72 feet and consists of 6 inches of hard blue hematite containing some sand and chert. The dip of the formation is strongly to the west, toward the middle of the sink.

A shallow pit sunk on the southeast edge of the rim shows some soft red ore and a cherty, ferruginous rim rock pitching to the northwest. In the ravine near the base of the west slope of the hill, are many shallow pits from which considerable hard, blue, silicious ore has been mined.

With the exception of the 102 foot shaft, the prospecting here has not been deep and has afforded little knowledge of the extent of the ore body. A position upon the hillside about midway between the open cut at the northeast end of the sink and the shallow diggings in the ravine at its base is suggested as the best point for further prospecting. On the whole, the well developed sink structure and the several showings of ore mark the property as worthy of a thorough investigation.

An analysis of the soft, red ore showed 55.37% iron and 0.075% Phos.