Bulletin - United States Geological Survey Volume 294
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1906 edition. Excerpt: ...For this region, however, the ore'is unusually free from iron sulphide. As a rule the tailings are clean, and the ore does not need roasting and cleaning. As much as 14 tons of concentrates is said to have been produced in a single mill shift. The concentrates are said to run from 50 to 60 per cent in zinc and 2 to 4 per cent in iron. When visited the plant consisted of an 80-ton concentrating mill, a cross-head pump, hoist, air compressor, and two drills, the whole driven by gasoline power. The mill started in July, 1903, but closed down soon after. Weber and Cring mine.--This mine includes several shafts along a crevice running N. 85 E. The top of the central working shaft is at an altitude of 813 feet. Galena is the only mineral shipped. The Dunkel and Link, a similar lead prospect, is located near by. Vinegar Hill mine.--In Vinegar Hill Township there are many old workings and the area has produced a large amount of lead. Efforts were made in 1903 to reopen several of these mines, among which was the Vinegar Hill mine. This is located in a small ravine running toward Fever River, the top of the shaft being 33 feet below the base of the Maquoketa shale. The crevice runs east and west and has yielded galena at a depth of 29 feet. A new shaft was sunk, and a drift run to the east 10 feet below the old workings. A very neat and effective equipment, with a gasoline engine for power, was in operation when the plant was visited. Fox River Valley mine.--At this mine there are two shafts on an east-west crevice, one more than 95 feet and the other 65 feet deep. The shafts begin a few feet below the base of the shale. Both galena and blende have been found in small quantity. Oldenburg 'nine.--This, probably the best known of the mines near...
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