The copper era., 1905-10-26
The Copper Deposits of the CIiftOn-MO.
 renci District, Arizona.

Morenci district, Arizona, were dis
 covered in 1872, but tor many year: their development was slow because only rich ores could be utilized, as the district was far from established lines of communication. Since 1890, however, the progress of the district has been rapid. At the present time large bodies of low-grade ore are utilized and production has reached high figures. A professional paper (No. 43) recently published by the United States geological survey will therefore be of interest to many. It is entitled "The Copper Deposits of the Clifton-Morenci District, Ari- zona,' and is the work of MT. Walde- mar Lindgren.
 The scope of MT. Lindgren's in- vestigation is very broad Besides discussing the general geology of the district, it's ore deposits and their minerals, and the principal char acteristics of these deposits, he de- votes a separate chapter to the metasomatic processes represented in the rock structure of this district, and describes the many mines in de- tail. The illustrations include twen- ty-fve photographic plates and nineteen figures. Among the plates is a geological map of the Clifton Morenci district and a geological and topogra phical map of the vicinity of Metcalf.
 In 1902 the total production of this district rose to 49,5O0,OO0 pounds of copper: in 1903 it had attained 53,- 4OO,O 900 pounds. with value of about S7, 100000 Two strong companies, the Detroit Copper company and the Arizona Copper company, have con tributed by far the greatest part of the production since 1882. Since 1902 a third, the Shannon Copper company. has been added. The mines of the Detroit company are To- cated at Morenci, those of the Ari- zona company at Morenci and Met calf, and those of the Shannon com pany at Metcalf. Of the production in 1903 the Arizona company con- tributed, 3O,22S,OOO pounds, the De troit company 16,558, ,232 pounds, and the Shannon company 6,600,OOO pounds. The total output of the district to the end of 1903 is esti- mated to be about POI, ,6OO short tons of copper.
 The ores mined average three or four per cent. of copper. The about 1000 short tons. Of this, 47,- 900 tons were classed as concentrating ore and 12,000 tons as higher grade smelting ore, with six to ten per cent. copper. The Arizona company smelted the lowest grade of ore, while the Detroit company averaged somewhat higher. The ores of the Shannon company were in 1902 eX clusively oxidized ores, containing about eight per cent. copper. Since then this company has also begun the mining of concentrating ore. By far the larger percentage of ore consisted of sulphide ore, containing pyrite and chalcoCite. Of oxidized ores about 5000 tons a month were mined at Metcalf, and a steadily diminishing amount from 1,500 tons a month at Morenci, making a total of 14, 300 tons, or about one-fourth the total production. The output of oxidized ore at Metcalf will continue for number of years and possibly increase. The oxidized ore mined by the Arizona Copper company at Metcalf is the lowest grade utilized in the district, and probably contains on an average less than three per cent.
 MT. Lindgren believes that the future of the camps is assured for many years, since the low grade ore bodies, which are now the mainstay of the district. are of very large ex- tent, and the production bids fair to keep up at least the present rate for some time to come. MT. Lindgren's paper is among the Surveys free publications, and may be obtained on application to the Director of the Geological Survey, Washington, D. C.-Miuiup World.