Mohave County miner., 1911-05-20
Copper And Zinc Mining.

common and are often thought of to- yether. As metals in the market, they are closely related, but contrast could scarcely he more striking than that between the copper-mining and zinc-mining industries, characteristic sketches of which appear in the Joplin letter, and the Arizona, Utah, and New York mining news of this issue. On the one hand is the story of the miner. who with homemade machin- cry impelled by a decrepit horse, has single-handed developed profitable zinc mine; on the other, bits of de- scription of mills handling 10000 tons per day, others In which 1000 tons is treated by a single unit, and finally, of the refusal of bid for a 50.000, ,000- pound lot of copper. There would seem to be no priori reason why the mining of one metal should remain in the hands of the individual small-scale producer, while that of the other has steadily and now almost completely passed into the control of the large producers. How complete this trans formation now is, in the case of cop- per, appears from a mere recital of the names of the more recent mines, Nevada Consolidated, Utah Copper, Ray Consolidated, Miami, Chino, Braden, and Cerro de Pasco. On the other hand, the great bulk of the zinc ore produced in the United States, and hence in the world, comes from small mines operated by men, many of whom began by taking a lease on a single acre, and gathering together such equipment as could best be as- sembled at night. The reason for this contrast lies deep, and exists ID the fundamental chara ,teristics of the two metals. Copper sells for two to four times the price of spelter, and as price in both metals is governed by supply and demand, copper must ac- cordingly be either scarcer or more useful than zinc. There is little evil dence that there is less of copper in the crust of the earth than there is of zinc. Indeed, the balance of evidence, slight as it admittedly is, would seem to point in the opposite direction. Copper, however, is capable of many uses denied zinc. Indeed, the latter is a metal of limited usefulness, and zinc smelters have had always the problem of creating a demand for their product. It can not be doubted, for example, that if zinc were equally as useful as copper in transmitting electric current, the price of copper would fall and that of zinc would rise. Taking conditions as they are, It is evident that in the case of a high priced metal it is possible to make a profit from ores of grade so low as to be unavoidable in the case of a low priced metal. Assuming equally per feet extraction, and in the case of cop per and zinc the difference in efficiency of treatment processes is not nearly so important as it was formerly, it should be possible to handle five tons of rock to get the same weight of one metal as from one ton of rock in the other case, if the selling price of the first metal is five times that of the second. In word, the higher price of copper makes it possible to work lower-grade ores. As is well known, lean ores are more common than rich, and occur in larger bodies. As general rule, ex- captions to which in case of copper and zinc are unimportant, rich ores char electrically shade by degrees into bar ren rock. Every increase in the price of metal or decrease in working costs, adds to the ore reserve in an ordinary copper mine. The great porphyry de- posits at Bingham now mined with steam shovels, were formerly worked for the copper found in much smaller and richer streaks running through the main deposit. Rock containing l-2 to ? l-2 per cent copper has become an ore, whereas rock containing that much zinc is worthless except for con crete or road ballast. Considering es- pecially the Joplin deposits, which are worked Orly for zinc and lead, and in which there is no gold and silver, there are, broadly, two types of de- posits: CD the rich irregular runs, and @ the lean but regular sheet ground. It was the runs that made the district, and they still are the mainstay of it's prosperity. The ma jority of these deposits lie near the surface, and once found, mining costs