Scientific American; Supplement Volume 53
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. 1902 edition. Excerpt: ...is not as high as is usually stated. The furnace yield of sorted ores ranges from about 8 per cent at the Bisbee mines to 12 or 15 per cent at some of the others, the closeness of the sorting depending upon cost of fuel, etc. In Arizona the deposits are mostly oxidized ores; in Montana they are sulphurets with some silver (for which they were originally worked); and in the Lake Superior region native copper is worked. The Montana veins are in the neighborhood of Butte, and are inclosed within a rough rectangle having a length of 2Mi miles and a width of Shout one mile. At its eastern end the mines are argentiferous, copper predominating in the west. A very large number of veins course through the granite hill. At the surface the copper contents were relatively low, silver being more perceptible; but whenligging was carried down to the waterline at a depth of 50 feet to 150 feet, the vein filling changed somewhat suddenly in character, being heavily charged with copper sulphurets, copper glance and peacock copper predominating. Many of the veins are known to be large, their thickness rising to more than 100 feet, although the average does not exceed 8 feet or 10 feet. The great mass of the ore is not rich, and runs to from 4 to 10 per cent of metal. There are many mines in this region, but interests are In relatively few hands, the most prominent companies being the Anaconda, Boston and Montana, Butte and Boston, Parrott, and the Butte Reduction Works. The future of the district was at a very early date seen to depend upon the successful utilization, commercially and technically, of the abundant stores of low-grade ores rather than upon the extraction of occasional bunches of rich ground. This has been accomplished. The mining presents...
- 189 x 246 x 46mm | 1,606g
- 13 Sep 2013
- United States
- black & white illustrations