Physiological medicine, salts of copper are used as astringents and as antiseptics, copper sulphate being the favorite salt. The soluble salts of copper are all exceedingly poi sonous, and since the metal is very widely used in the arts, copper poisoning is quite common. In acute poisoning the symptoms are those of an acute gastro-intestinal irritant. These usually develop in from 10. to 20 minutes, though they may he delayed as much as two or three hours. There is nausea and vomiting of bluish mate rial, accompanied by a metallic taste in the mouth, and intense burning in the stomach, with great abdominal tenderness. If all the copper is ejected by the emesis, the patient usually re covers. This is usually the case, but sometimes, when the dose is extremely large, vomiting is ineffectual. In additiOn to the symptoms already given, intense headache then develops, accom panied by great prostration and cramps, with small, rapid pulse and collapse; 'death some times following in from 4 to 12 hours, but more commonly after two to four days or more.
Ores and Native copper oc curs in nature, and in the Lake Superior district (Michigan), forms the chief ore. Chalcocite (Cu2S), chalcopyrite (CuFeS2), bornite (CusFeSs), enargite (CtaAsS4), eovellite (CuS), tet rah edrite (CueSb:ST ), azurite 12CuCO..Cu (OH )2], malachite [CuCO2.Cu (OH)2], chrysacolla (CuSi02.21120) and cuprite (Cu20), are all important ores.
Practically all our important copper deposits are the result of heated waters related to vol canic activity. Typical contact metamorphic de posits are found in the Clifton-Morenci district of Arizona and in the limestone deposits of Bingham, Utah. Bisbee, Ariz., and Ely, Nev., are also classed with this type. The Butte, Mont., ores are typical vein deposits formed by hot waters. Globe, Bisbee and Clifton-Morenci all show typical replacement deposits in lime-. stone. The Bingham camp in Utah is now noted for its enormous bodies of low grade dis seminated ore in porphyry. The Globe, Miami and Ray districts of Arizona contain great dis seminated deposits in Pre-Cambrian schists. The Lake Superior ores are chiefly native cop per, occurring in the vesicular openings (amyg dules) of lava flows, or replacing interbedded layers of conglomerate. As indicated above, one district may show several types of ore de posit. See ORE DEPOSITS.
The greatest copper producing locality in the United States, and therefore in the world, is the Butte district of Montana. The copper veins are confined to a comparatively small area lying north of Silverbow Creek, about two miles in length and one and one-half miles in width. Several of the mines now producing
copper were opened as silver mines, the silver being replaced by copper at the depth of about 150 feet. This locality produced in 1916 349, 500,000 pounds of copper, equivalent to 17.42 per cent of the entire output of the country. Inclusive of this amount the total production of this region since it was opened in 1868 has been 7,030,000,000 .2unds — an output larger by more than 1,000,111,000 pounds than any other copper-yielding region known. The ore most common in this region, and which has supplied 75 per cent of the entire output, is chalcocite, or copper glance—a sulphide, carrying 79.8 per cent of metallic copper. This ore was originally pyrite, and has been altered by hot descending waters containing copper sulphate. About 20 per cent of the Butte copper production has been from enargite, a sulpharsenate of copper, carry ing 48.67 per cent of the metal. About 4 per cent has been recovered from bornite, an altered chalcocite, carrying 63.3 per cent of copper. The remainder has been pined from covellite, chalcopyrite and tetrahedrite.
Two other localities in the United States are eminent as producers of copper: the Keweenaw (Lake Superior) district of Michigan and the Bisbee district of Arizona. The former has a record of 6,029,777,236 pounds since its first production in 1845, practically all recovered as native copper. The Bisbee district began pro duction in 1880, and its record stands at 2,219, 556,000 pounds. Four other districts in Arizona have contributed to swell the grand total for the State to 5,767,698,935 pounds since the first mine within its borders was opened in 1873. The ores of Arizona are virtually the same as in Montana, the upper earth section being barren through having its copper leached away for a depth of about 250 feet and deposited in the veins of the 100-foot zone below. Chalcocite is the principal ore, altered in places to chg• copyrite, bornite, covellite and melaconite.
Smelting and Refining.— Mining the ore is but the preliminary step in the production of commercial copper. The crude ores must be smelted and the smelter product refined. The first treatment the ore receives after being raised is concentration. This is a mechanical treatment with the object of eliminating as much as possible of the gangue or non-ore bearing rock accompanying the ore. It makes use of the methods of hand-picking, wet and dry jigging tables and hydraulic separation. The ore then goes to the smelter.