110 DESCRIPTIONS OF MIN.RALS. 
Composition. Native gold usually contains silver, and in 
very various proportions ; and the color becomes paler with 
the increase of silver. The finest native gold from Russia 

yielded gold 98-96, silver 0:16, copper 0°35, iron 0:05 ; 
G.=19-099. A gold from Marmato afforded only 73°45 per 
cent. of gold, with 26°48 per cent. of silver; G.=12°666. 
This last is in the proportion of 3 of gold to 2 of silver. The 
following pypportions also have been observed : 33 to 2; 5 
to 2; 3toil; 4 to1, and this the most common; 6 to 1 is 
also of frequent occurrence. Average of California native 
gold is 88 per cent. gold, and the range mostly between 87 
and 89; the range of the Canadian, mostly between 85 and 
90; of Australian, between 90 and 96 per cent., and the 
average 934. ‘I'he Chilian gold afforded Domeyko 84 to 96 
per cent. of gold, and 15 to 3 per cent. of silver. ‘The more 
argentiferous gold has been called Hlectrum; the atomic pro- 
portion of 1:1 between the gold and silver corresponds to 
35°5 per cent. of silver, and that of 2:1, to 21°6 per cent. 
Copper is occasionally found in alloy with gold, and some- 
times also iron, bismuth, palladium andrhodium. A rhodiwm- 
gold from Mexico gave the specific gravity 15°5-16°8, and. 
contained 34 to 43 per cent. of rhodium. A bismuth gold 
has been called Maldonite. 
Diff. Tron and copper pyrites are often mistaken for gold 
by those inexperienced in ores ; but these are brittle minerals, 
while gold may be cut in slices, and flattens under a hammer. 
Pyrite is too hard to yield at all to a knife, and copper 
pyrites affords a dull greenish powder. Moreover pyrite 
gives off sulphur when strongly heated, while gold melts 
without odor. 
