28 B. Silliman—Mineralogical Notes. 
with soda it gives a large bead of silver, which dissolves in 
nitric acid, leaving gold in powder. 
Cupellation gave gold 6-40 per cent, and silver 50-90. 
By a partial analysis I found, in the wet way, gold 7-131; silver 
51°061 per cent. Understanding from Dr. Genth that he is en- 
ed in the chemical investigation of this species, as well as of 
the other tellurium minerals of the Red Cloud Mine, with abun- 
dant material, I have willingly abandoned this work to him, 
satisfied that it cannot be in better hands. 
Sylvanite.— This species from the Red Cloud Mine yields in 
the open tube a faint odor of selenium, and the gray ring of 
deep yellow-brown vapor of the metal is clearly seen, but the 
selenium is not evident. 
Alone on the coal it fuses with exhalation of the odor of se- 
lenium and its well characterized blue flame. The first touch 
darkest colored—assayed here, was found to contain 1890 
ounces of gold and 5300 ounces of silver to the ton of 2000 
val 
recent than the Triassic rocks which flank the base of the moun- 
