138 DESCRIPTIONS OF MINERALS. 



Composition. Cu t S + 5 aq= Sulphuric acid (or sulphur 

 trioxide) 32*1, copper oxide 31*8, water 36-1. A polished 

 plate of iron in solutions becomes covered with copper. 



Obs. Occurs with the sulphides of copper as a result of 

 their decomposition, and is often in solution in the waters 

 flowing from copper mines. Occurs in the Hartz, at Fahlun 

 in Sweden, and in many other foreign copper regions ; in 

 the Hiwassee copper mine, Tennessee ; the Canton mine, 

 Georgia ; at Copiapo, Chili. 



Blue vitriol is much used in dyeing operations and in the 

 printing of cotton and linen ; also for various, other pur- 

 poses in the arts. It has been employed to prevent dry rot, 

 by steeping wood in its solution : and it is a powerful pre- 

 servative of animal substances ; when imbued with it and 

 dried, they remain unaltered. It is afforded by the decom- 

 position of copper pyrites, in the same manner as green vit- 

 riol from iron pyrites ; but it is manufactured for the arts, 

 chiefly from old sheathing-copper, copper turnings, and cop- 

 per refinery scales. 



In Frederick County, Maryland, blue vitriol is made from 

 a black earth which is an impure oxide of copper w r ith cop- 

 per pyrites. 



In some mines, the solution of sulphate of copper is so 

 abundant as to afford considerable copper, which is obtained 

 by immersing clean iron in it, and is called copper of cemen- 

 tation. At the copper springs of Wicklow, Ireland, about 

 500 tons of iron were laid at one time in the pits ; in about 

 12 months the bars were dissolved, and every ton of iron 

 yielded a ton and a half, and sometimes nearly two tons, of 

 a precipitated reddish mud, each ton of which produced 16 

 cwt. of pure copper. The Eio Tinto Mine in Spain is an- 

 other instance of working the sulphate in solution. These 

 w r aters yield annually 1,800 cwt. of copper, and consume 

 2,400 cwt. of iron. 



Brochantite. An insoluble copper sulphate, containing 17*7 per 

 cent, of sulphur trioxide. Color emerald-green. In tabular rhombic 

 crystals, from the Urals, Retzbanya, Cornwall, Mexico, Chili, Aus- 

 tralia. Krisuvigitc and Koirigite are the same species. 



Lwngite, Cyanotriehite (Velvet copper ore, Kronkite, Philippite, 

 Enysite, Li rid rite, Dolerophanite, Eydrocyanitc , are other sulphates 

 containing copper, the last two anhydrous ; and Connellite is another 

 containing chlorine, from Cornwall/ 



The Copper tungstate, Cuprotungstite, occurs of a yellowish-green 

 color in Chili. 



