470 NATURAL HISTORY. 



Native Silver occurs in various forms, as compound 

 crystals, coarse and fine filiform shapes, reticulated, 

 string-like or arborescent; also in plates, superficial 

 coatings, and granular, compact masses. Color and 

 streak silver-white ; subject to tarnish, by which the 

 color changes to yellowish or grayish-black. Luster 

 metallic, opaque; ductile, malleable. Dissolves in 

 nitric acid, and with a solution of sea-salt and cream 

 of tartar, precipitates as chloride of silver. H. = 2.5 

 to 3.0. G. = 10.3 to 10.5. Chemical sign . The 

 European localities which have afforded the finest speci- 

 mens of native silver are Konigsberg in Norway (these 

 mines are now mostly under water), Saxony, Freiburg, 

 Schneeberg, Black Forest, the Hartz and Ural moun- 

 tains, also in the Altai at Schlangenberg, and in some 

 of the Cornish mines. Occurs mostly in the primary 

 and transition rock formations. 



No silver mines, however, can compete with those of 

 Peru, Chili, and Mexico. One specimen brought from 

 the latter weighed four hundred pounds ; another, from 

 the mines of Huantaga, weighed over eight hundred 

 weight. During the first eighteen years of the present 

 century more than 8,180,000 marks of silver were 

 afforded by the mines of Guanaxuoto alone. Since the 

 discovery of the rich silver mines of America, the 

 amount of the precious metal obtained is enormous. 

 These alone, in three hundred and eleven years, have 

 furnished 512,700,000 marks of silver. Upon the 

 whole, it is calculated that at the present time 3.924,000 

 marks of pure silver are obtained from the American 

 mines, and of the 8,000,000 sterling which is calculated 

 as the value of the silver annually furnished by the 

 mines of the world, two-thirds are obtained from Mex- 



