910 COPPER 



ore is generally valued for tho silver which it contains rather than for its copper. It 

 is very difficult to convert into pure copper by smelting, on account of the presence of 

 antimony and arsenic. See FAHI.KU/. 



Tfimaaiite. An arsenic-sulphide of copper and iron, closely allied to Fahlerz. It 

 was formerly obtained crystallised in rhombic dodecahedra, from Wheal Jewell, in 

 Gwonnap, and from some other Cornish mines. This species is rare. 



Cuprite, Bed Oxide of Copper, Ruby Copper Ore, or Sub-oxide of Copper, (Cuim-e 

 oxidtcU, Fr. ; Bothkupfererz, Ger.). This mineral frequently occurs in fine octahedral 

 and cubic crystals, associated with other ores in tho shallow workings of copper-mines. 

 Its colour is a deep red, sometimes very bright, especially when bruised. It is friable, 

 difficult of fusion at the blowpipe, reducible on burning charcoal, soluble with effer- 

 vescence in nitric acid, forming a green liquid, and also soluble in ammonia. Cuprite 

 is a sub-oxide of copper (cuprous oxide), Cu 2 0, containing, when pure, copper 88 - 8, 

 and oxygen 11 '2. The impure compact varieties, associated with much iron ochre, 

 have been Killed tile-ore, whilst certain delicate capillary varieties are known as plush 

 copper ore or chalcotrichite. 



Melaconite, or Slack Oxide of Copper, (Cuivre oxide, Fr. ; Kupferschwarzc, Ger.). 

 The native protoxide of copper (cupric oxide), CuO, generally occurs as a black earthy 

 or pulverulent incrustation on other copper ores, from which it has been produced by 

 decomposition. 



Malachite or Green Carbonate of Copper. This mineral is found in most deposits 

 of copper ore, especially in the upper parts whore atmospheric influences have been 

 active. It is a hydrous carbonate of copper, corresponding, when pure, with the for- 

 mula, 2CuO,C0 2 + HO (2CuCO" + H 2 0) : this requires 71 '9 per cent, of protoxide of 

 copper, 19'9 of carbonic acid, and 8'2 of water. Malachite is found earthy, compact, 

 stalactitic, or mammillated. The finest examples, sometimes polished as ornamental 

 stones, come from Siberia, and from Burra Burra in South Australia. 



Azurite, Chessylite, Blue Malachite, or Blue Carbonate of Copper. A hydrous car- 

 bonate of copper containing in its purest forms 2(CuO.C0 2 ) + CuO.HO (2CuCO J 

 + CuH 2 O 2 ); which corresponds to protoxide of copper 69'2, carbonic acid 25'6, and 

 water 5'2. Azurite thus differs from malachite in chemical composition and in colour ; 

 it is also more prone to crystallise, and magnificent specimens were formerly obtained 

 from the copper-mines of Chessy, near Lyons. 



Chrysocolla. This mineral, which is a hydrous silicate of copper of variable com- 

 position, somewhat resembles carbonate of copper, and commonly occurs as a green, 

 bluish-green, or turquoise-blue incrustation on other copper ores. A black resinous 

 variety, impure by the presence of much iron, is generally known as pitch copper 

 ore. 



Dioptase or Emerald Copper. A beautiful but rare silicate of copper occurring in 

 emerald-green crystals, composed of CuO.SiO 2 + HO (CuSiO 3 + H 2 O). It is found in 

 the Kirghese Steppes and in Chili, but cannot be called an ore of copper. 



Atacamite. An oxychloride of copper containing CuCl + 3 (CuO.HO) or CuCl 

 + 3CuH-'O. This corresponds to copper 15, chlorine 16, protoxide of copper 56, 

 and water 12. It occurs in fine rhombic crystals of a greenish black colour, and is 

 worked as an ore at the Wallaroo and other copper-mines on Yorke Peninsula. 

 South Australia. It is also found in tho form of a green sand in the Desert of 

 Atacama. 



Phosphates of Copper. Several copper-bearing minerals containing phosphoric acid, 

 with or without its isomorph arsenic acid, are known to the mineralogist, but none of 

 them occur in sufficient abundance to be used as ores. Libethenite it> a hydrous 

 phosphate, occurring in rhombic crystals at Libethen in Hungary ; and Ehlite is a 

 similar mineral from Ehl in Nassau. 



Arsenates of Copper. A large number of these compounds are known, but are only 

 of mineralogical interest. Among these are the species named olivenite, euchroite, 

 tagilito, tyrolite, liroconite, cornwallite, and chalcophyllite or copper-mica. 



Chalcanthite, Cyanosite, Blue Vitriol, or Sulphate of Copper. A mineral similar to 

 the artificial salt of the laboratory. The blue water which flows from certain copper- 

 mines is a solution of this salt. The copper is easily procured in the metallic state 

 by plunging into it pieces of iron. 



It should be remarked that many of the minerals noticed above are not available as 

 ores of copper. Dr. Scherer, of Freiberg, has arranged the principal ores of copper as 

 follow : 



Copper in 100 



1. Copper Glance, Cu 2 S 797 



2. Copper pyrites, Cu 2 S, Fe"S s 34'8 



3. Buntkupfererz, 3Cu 2 S, Fe 2 S* 557 



4. Fahlerz, 4(Cu'S, FeS, ZnS, AgS) (SbS 3 ,AsS 3 ) , . 1441 



