290 METALS. 



with native mercury and cinnabar, with but little visible. These mines 

 afford annually about 25.000 cwt. of mercury. The granitic and por- 

 phyritic eruptions of the region have been supposed to account for the 

 presence of the mercury in the rocks : the heat produced exhalations 

 of mercury and sulphur, which gave origin both to the cinnabar and the 

 native mercury. 



The mines of Huanca Velica, in Peru, have afforded a large amount 

 of mercury for amalgamation at the Peruvian silver mines. Between 

 the years 1570 and 1800, they are estimated to have produced 537.000 

 tons ; and their present annual yield is 1800 quintals. 



The Chinese have mines of cinnabar in Shensi, where the ore is re- 

 duced by the rude process of burning brushwood in the wells or pits 

 dug out for the purpose, and then collecting the metal after condensa- 

 tion. 



23. COPPER. 



Copper occurs native in considerable quantities ; also 

 combined with oxygen, sulphur, selenium, and various acids. 



The ores of copper vary in specific gravity from 3*5 to 8*5, 

 and seldom exceed 4 in hardness. Many of the ores give to 

 borax a green color in the outer flame, and an opaque dull- 

 red in the inner. With carbonate of soda on charcoal, 

 nearly all the ores are reduced, and a globule of copper ob- 

 tained ; borax and tin foil are required in some cases wh^rts 

 a combination with other metals conceals the copper. [When 

 soluble in the acids, a clean plate of iron inserted in the so- 

 lution becomes covered with copper, and ammonia produces 

 a blue solution. 



NATIVE COPPER. • 



Monometric. In octahedrons ; no cleavage apparent 

 Often in plates or masses, or arborescent and filiform shapesA 



Color copper-red. Ductile and malleable. Hs=25 — 3." 

 Gr=8-58. 



Native copper often contains a little silver, disseminated / 

 throughout it. Before the blowpipe it fuses readily, and on / 

 cooling it is covered with a black oxyd. Dissolves in ni- / 

 trie acid, and produces a blue solution with amrronia. 



Obs. Native copper accompanies the ores of copper, and/ 

 Usually occurs • in the vicinity of dikes of igneous rocks. / 



How does copper occur 1 flow are copper ores distinguished ? Whnl 

 are the characters of native copper? 



J 



