140 DESCRIPTIONS OF MINERALS. 



Malachite. — Green Copper Carbonate. 



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. Lustre of crystals adamantine inclin- 

 ing to vitreous ; but fibrous incrustations silky on a cross 

 fracture. Earthy varieties dull. H. = 3*5-4. G.=3*7-4. 



Composition. Cu 2 4 C -f H 2 = Carbon dioxide (or car- 

 bonic acid) 19-9, copper oxide 71*9, water 8*2 = 100. Dis- 

 solves with effervescence in nitric acid. 



B.B. decrepitates and blackens, colors the flame green, 

 and becomes partly a black scoria. With borax it fuses to a 

 deep-green globule, and ultimately affords a bead of copper. 



I) iff. Readily distinguished by its copper-green color and 

 its associations with copper ores. It resembles a siliceous 

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

 Mississippi Valley; but it is distinguished by its complete so- 

 lution and effervescence in nitric acid. The color also is not 

 the bluish green of chrysocolla. 



Obs. Green malachite usually accompanies other ores of 

 copper, and forms incrustations, which, when thick, have 

 the colors banded and delicate in their shades and blending. 

 Perfect crystals are quite rare. The mines of Siberia, at 

 Nischne Tagilsk, have afforded great quantities of this ore. 

 A mass, partly disclosed, measured at top 9 feet by 18 ; and 

 the portion uncovered contained at least half a million 

 pounds of pure malachite. Other noted foreign localities 

 are Chessy, in France ; Sandlodge, in Shetland ; Schwatz 

 in the Tyrol ; Cornwall ; the Island of Cuba ; Serro do 

 Bembe, west coast of Africa ; copper mines of Australia ; 

 Chili. 



The copper mine of Cheshire, Conn., has afforded hand- 

 some specimens ; also Morgantown, Perkiomen, and Phcenix- 

 ville, Penn. ; Schuyler's "Mine, and the New Brunswick 

 copper mine, X. J. ; it occurs also in Maryland, between 

 Newmarket and Taneytown ; and in the Catoctin Mountains ; 

 in the Blue Rido-e, Penn., near Nicholson's Gap ; also in 



ntic district, Utah. 

 TiAt Mineral Point, Wisconsin, a bluish silico-carbonate of 

 oepper occurs, which is for the most part chrysocolla, or a 

 mixture of this mineral with the carbonate. 



