116 DESCRIPTIONS OF MINERALS. | 
55°5, gold 44:5—100, with a little silver, occurring massive at the Stan- 
islaus Mine, California, and the Red Cloud Mine, Colorado, and alse 
the Keystone and Mountain Lion mines, in the Magnolia Disirict. 
Kreunerite is another gold telluride. 
Sylvanite, called also Graphic tellurium, is a telluride of gold and 
silver, also containing sometimes antimony and more or less lead (see 
p- 118). 
Nagyagite is a telluride of lead containing 9 to 18 per cent. of gold 
(see p. 149). 
Peizite is a telluride of silver, allied to Hessite (p. 118), containing 
gold ; a specimen from Golden Rule Mine, Colorado, contained 25°60 
per cent, according to Genth. 
If. SILVER. 
Silver occurs native, and alloyed, or combined with gold ; 
also combined with sulphur, selenium, tellurium, arsenie, 
antimony, bismuth, chlorine, bromine, or iodine; but never 
as an oxide, carbonate, sulphate, or phosphate. 
Native Silver. 
Isometric. In octahedrons and other forms. No cleavage 
apparent. Occurs often in filiform and arborescent shapes, 
the threads having a crystalline character ; aiso in lamine, 
and massive. 
Color and streak silver-white and: shining. Often black 
externally from tarnish. Sectile. Malleable. H.=2-5-3. 
G10 111-1: 
Composition. Native silver is usually an alloy of silver 
and copper, the latter ingredient often amounting to 10 per 
cent. It is also alloyed with gold, as mentioned under that 
metal. <A bismuth silver from Copiapo, 8. A., contained 16 
per cent. of bismuth. 
B.B. fuses easily to a silver-white globule. Dissolves in 
nitric acid, from which it is precipitated as white chloride 
on adding hydrochloric acid. A clean plate of copper im- 
mersed in the nitric solution becomes coated with silver. 
Diff. Distinguished by being malleable ; from bismuth 
aud other white native metals by affording no fumes before 
the blowpipe ; by affording a precipitate with hydrochloric 
acid which becomes black on exposure. 
Obs. Native silver occurs in masses and string-like ar- 
borescences, penetrating the gangue, or its minerals, in 
