302 



METALS. 



has a perfect cleavage. It contains 25 per cent, of arsenic acid. 43.9 

 of oxyd of copper, 175 of water, with 136 of carbonate of lime. From 

 Hungary, Siberia, the Tyrol, and Derbyshire. Condurrite has a brown- 

 ish-black or blue color. From Cornwall. These different arsenates of 

 copper give an allicaceous odor when heated on charcoal before the 

 blowpipe. 



Phosphates of Copper. — Pseudo-malachite occurs in very oblique 

 crystals, or massive and incrusting, and has an emerald or blackish- 

 green color. H=4-5— 5. Gr=4-2. Contains 68 per cent, of oxyd 

 of copper. From near Bonn, on the Rhine, and also from Hungary. 

 Libethenite has a dark or olive-green color, and occurs in prismatic 

 crystals and massive. H=4. Gr=36— 38. Contains 64 per cent, 

 of oxyd of copper. From Hungary and Cornwall. Thromholite is a 

 green phospate occurring massive in Hungary. Contains 39 per cent, 

 of cxyd of copper. These phosphates give no fumes before the blow- 

 pipe ; and have the reaction of phosphoric acid. 



Chlorid of Copper. — Atacamite. Color green to blackish-green. 

 Luster adamantine to vitreous. Streak apple-green. Translucent to 

 subtranslucent. Occurs in right rhombic prisms and rectangular octa- 

 hedrons, also massive. Consists of oxyd of copper 76*6, muriatic acid 

 10-6, water 12-8. Gives off fumes of muriatic acid before the blowpipe 

 and leaves a globule of copper. From the Atacama desert, between 

 Chili and Peru, and elsewhere in Chili ; also from Vesuvius and Sax- 

 ony. It is ground up in Chili, and sold as a powder for .etters undei 

 the name of arenillo. 



A Sulphato-chlorid of Copper has been observed in Cornwall, in blue 

 acicular crystals, apparently hexagonal. 



Vanadate of lead and copper. Reported as occurring in Chili. 

 Color dark brown or brownish black ; texture earthy, looking like a 

 ferruginous earth. Occurs with other ores of lead and copper. 



Vanadate of copper. Massive and foliated, or pulverulent ; folia 

 citron-yellow, pearly. From the Ural. 



Buratite. A hydrous carbonate of copper, zinc, and lime, occurring 

 in bluish radiating needles. Gr=32. From Chessy, France ; the Al- 

 tai mountains; and Tuscany. Probably same as Aunchaleite. 



Velvet Copper Ore. In velvety druses or coatings, consisting of 

 short fine fibrous crystallization. Color fine smalt blue. 



GENERAL REMARKS ON COPPER AND ITS ORES. 



The metal copper has been known since the earliest periods. It is 

 obtained for the arts mostly from pyritous copper, the gray sulphurets, 

 and the carbonate ; also to some extent from the black oxyd, and from 

 solutions of the sulphate, (page 296.) 



Assay of Ores. For the assay of copper ores by the dry way, tlr * 

 ollowing is a common method. A portion of the prepared ore, roasted 

 n a closed tube, will show by the garlic or sulphurous smell of the 

 umes, and by the depositions on the tube, whether arsenic, sulphur, or 

 oth, be the mineralizers. If this last is the case, which often happens, 

 00 or 1000 grains of the ore are to be mixed with < ue half of its 

 veight of sawdust, then imbued with oil, and heated moderately in a 



What is the mode of assaying copper ores in the dry way 1 



