F. A. Genth—Contributions to Mineralogy. 311 
Not all the tellurid of silver from the Stanislaus mine, how- 
ever, is petzite ; there occurs also the other variety, which does 
not contain any, or only a very small percentage of gold, as 
1 
again, after having been thoroughly washed, but it was impos- 
m8 to obtain it free from quartz, tellurid of nickel and free 
0 
It was necessary, therefore, for the purpose of ascertaining the 
condition in which the gold was present, whether as tellurid 
or free gold, to make a careful analysis of the free gold asso- 
ciated with the Stanislaus mine tellurids, and from the amount 
of silver remaining with the gold, after treating the mineral 
with nitric acid, both the amount of free gold and that of tel- 
lurid of gold was determined. The free gold contains: 
Gold, 88°63 per cent. 
Silver, 1°37 es 
100°00 
The purest hessite (I), after deducting 721 p. c. of admix- 
tures, of which 4-22 p.c. were of free gold and the balance quartz, 
and a less pure specimen (II), which contained 28°60 p. c. of 
admixtures, of which 6 p.c. were of free gold, gave: 
Requires Te. 16% Requires Te. 
1°0 3°22 4 
Gold, 3°28 05 for AuTe 
Silver, 46°34 27°45 55°60 32°95 “ AgTe 
Lead, 165 1°02 wae siae ce PDL 
Nickel, 4°71 15°32 1°54 B01. .% NisTe,y 
Tellurium, 44°45 39°64* 
: 100° 44°85 10000 39°01 
This would be equal to: : 
Hassite, 2.62 cession chee 78°11 92°82 
Altsite, ..... ..---ssa0¢ cee Oop 2°67 Bg 
Melonite, =~. . -..--- ates 2-0 2 2008 PE ig 
Ratio of Au: Ag in the hessite in I=1: 25; in W=1: 31. | 
There certai ists also the variety of hessite, which is 
nly exists hessite, W! Je 
entirely free fees coll: that which was mixed with the impure . 
