r.99 MRTALS. 



s evaporated for crystals. 400 000 lbs. is the annual con. 

 •umption of blue vitriol in the United States. 



In Frederick county, Maryland, blue vitriol is made from 

 i black earth which is an impure oxyd of copper with cop- 

 per pyrites. The black oxyd of copper, which was found 

 <n the Lake Superior copper region, may *be directly con. 

 /erted into blue vitriol. 



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

 aoundant as to afford considerable copper, which is obtained 

 wy 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 pre- 

 cipitated reddish mud, each ton of which produced 16 cwt. 

 of pure copper. The Rio Tinto Mine in Spain, is another 

 instance of working the sulphate in solution. These waters 

 yield annually 1800 cwt. of copper, and consume 2400 cwt. 

 of iron. 



Brochantite. An insoluble sulphate of copper, containing 175 per 

 cent, of sulphuric acid. Color emerald green. In tabular rhombic crys- 

 tals, at Katherinenberg, in Siberia. Blackens before the blowpipe with- 

 out fusing. Krisuvigite and Konigite are the same species. 



malachite. — Green Carbonate of 'Copper. 



Monoclinic. Usual in incrustations, with a smooth tube- 

 rose, botryoidal or stalactitic surface ; structure finely and 

 firmly fibrous. Also earthy. 



Color light green, streak paler. Usually nearly opaque ; 

 crystals translucent. Luster of crystals adamantine incli- 

 ning to vitreous ; but fibrous incrustations silky on a cross 

 fracture. Earthy varieties dull. H=3*5 — 4. Gr=4. 



Composition : carbonic acid 20, oxyd of copper 71*9, wa- 

 ter 8'2. Dissolves with effervesence in nitric acid. De- 

 crepitates and blackens before the blowpipe, and becomes 

 partly a black scoria. With borax it fuses to a deep green 

 globule, and ultimately affords a bead of copper. 



Dif. Readily disti iguished by its copper-green color and 

 its association with copper ores. It resembles a siliceous 

 ore of copper, chrysocolla, a common ore in the mines of 

 he Mississippi valley ; but it is distinguished by its complete 



What is the composition of green malachite ? How is it distia 

 guished ? 



04* 



