COPPER, is qne of the most anciently known metals, and its name is derived from the island of Cyprus, where it was first obtained by the Greeks. In time earlier times C. does not appear to have been employed by itself, but always in admixture with other metals, principally tin, forming what is now called bronze (q.v.). There is every reason to believe, that next to the large quantities of tin which they obtained, one of the great inducements which the Phemcians had in making searches for metals in Great Britain, was the C. which they procured in their workings in Cornwall.
C. is sometimes met with in nature in a state of purity, but generally it is associated with oxygen. water, and carbonic acid, forming the native carbonate of C. or malachite (010,110-Ku° , or with iron and forming the native sulphurets of C. and iron or C. pyrites (Cu2S,Fe2S.). In smaller quantity, C. occurs as the oxide (Cu0), and sulphate (Cu0S0.), and in all cases the ore is obtained from fissures or veins in other rocks. The principal yield of C. ore in Great Britain is from the mines in Cornwall, but large supplies are also obtained from Australia, and from Cuba and Chili in .South America. In North America, iu the neighborhood of lake Superior, C. ore occurs abundantly, and a vein of metallic C. is there found which iu some places is about 2 ft. in thickness.
In the extraction of C. from its ores, the metallurgic processes followed are very tedious and complicated, which mainly arises from the difficulty of separating the iron and sulphur from the copper. The general principle which regulates the working-up of the ore is to burn away the sulphur (8) as sulphurous acid and to carry off the iron by means of fluxes in the form of scorite or slag. Metallurgists enumerate ten distinct steps in the production of commercially pure copper.
C. (symb. Cu, from Lat. euprum) has the equiv. 31.7—new system, 63.4. It is the only red metal, has the specific gravity 8.78 when cast, and 8.96 when rolled or ham mered; fuses at 1996° F. (Daniell), and at a white heat passes off in vapor, and burns with a green flame. It is very malleable, and can thus be beaten out into thin leaves; is very ductile, so as to admit of being drawn out into thin wires; and its tenadity is only inferior to that of iron. It is a powerful conductor of electricity, and hence is employed in the construction of lightninw-conductors, and in telegraph-wires for under ground or submarine communication. C. is also employed largely in the sheathing of wooden vessels, and in the coinage. See also ALLOY.
C. forms many compounds. There are two oxides, the black oxide (CuO) and the
red oxide The latter is employed in coloring glass of a ruby-red tint. The green rust which forms on the surface of a copper-sheeted ship, and ou C. coins and vessels which lie in moist places for some time, is a carbonate of C., and is due to the carbonic acid and oxygen of the air acting upon the C. in the presence of moist ure. It is very poisonous, and hence any barnacles which may attach themselves to the C. sheathing are poisoned. The carbonate of C., under the name of blue verditer, is largely prepared and sold as a pigment. The subchloride of C., moistened and exposed to the air, yields the pigment known as Brunswick green. There are several compounds obtained by allowing acetic acid to act upon oxide of C., which are commercially called blue and green verdigris. The sulphate of C., or blue vitriol is prepared by dissolving the black oxide in sulphuric acid, and allowing the salt to crystallize out.
i The crystals are large, and present a fine blue color. It is soluble in water, and is extensively used by the dyer and calico-printer for the production of several blue and green colors. The solution of blue vitriol is also employed in the preservation of tim ber from dry rot, and it forms a constituent of some writing inks.
Mineralogy.—Native C. is not of very rare occurrence; it is sometimes massive, or in grains, plates, etc. ; sometimes crystallized in cubes or octahedrons; sometimes it assumes dendritic and other beautiful forms. Great masses of native C. have been found both in North and South America.—What are called C. ores in commerce, generally consist of the true ore disseminated through rock, and are therefore very variable in productive ness. A C. schist is profitably wrought at 3fansfeldt, iu Germany, although it yields only one per cent of copper. Among the most plentiful and valuable C. ores is the C. pyrites already mentioned, or yellow Core; but there is a richer ore called purple C. or variegated C., or bornitc, also a compound of sulphur, C., and iron. Malachite and azur ite, both consisting essentially of carbonate of C., are valuable ores; as are some ores which are essentially composed of oxygen and C., red C. ore (cuprite) and black C. ore (tenorite). Some ores of C. contain also silver, and some contain arsenic. antimony, etc. Gray C. ore is very compound, containing silver, mercury, zinc, anti mony, arsenic, iron, and sulphur. Atacamite, wrought as an ore of C. in South America, is composed of chloride of C. and hydrochlorate of copper.