Morenci (140c25b4-54d6-4e49-92dd-6573000e9615)

ONE of the problems that confronts the chronicler of the Porphyry story is to determine the date from which Morenci should be regarded as one of the group. The mines have the distinction of being the first operated in Arizona for copper. A small smelter was in operation as early as 1873 and in the eighties two smelters accounted for a substantial production ranging from 3,000,000 to 6,000,000 lb. per year. The first concentrator was built in 1886, but the ores were principally oxidized, and direct smelting ore still supplied most of the production. As early as 1893, the mining of somewhat leaner porphyry ores, containing copper in the form of the sulphide mineral, chalcocite, was commenced; but these still were of comparatively high grade and the concentrators were plants of 100 to 400 tons daily capacity. Moreover, the backbone of operations was still the production of rich oxidized ores for direct smelting. They assayed 10 to 15 per cent copper and the sulphide milling ores assayed 3 to 4 per cent. A significant comment appears in the Copper Handbook for 1908. Speaking of the Arizona Copper Co., Ltd., which was to become the most important component of the present Morenci enterprise, the editor, Horace Stevens, says: "A tremendous amount of ore is in sight, ore reserves . . . being estimated at 10,370,600 tons . . . " It seems fair to infer from this that the property was not yet regarded as an immense low-grade mine, but that the copper content of perhaps 70 lb, to the ton made an ore of "medium " grade even according to the standards of the time. Although the concentrating ore was typical of that in the porphyry group of mines (except for its greater richness), no one seems to have the least inclination to take from Utah the