B. Silliman—Mineralogical Notes. 27 
not found in the body of the dike, but have (owing probably to 
the long continued high temperature of the dike) found lodge- 
ment in the granite outside of the walls, and not in immediate 
contact with them. 
he species at the Red Cloud Mine are native tellurium, 
sylvanite and hessite (which has been called petzite). The 
simplicity of the mineralogy of this locality is in strong contrast 
with what is found in the tellurium veins of Transylvania, 
which are mentioned more particularly farther on. 
Native Tellurium.—The occurence of this rare species in the 
United States, in California, was mentioned by Dr. Genth with 
a query, in his Contributions to Mineralogy, No. vii (this Journal 
IT, xlv, 318). Its existence in the Red Cloud Mine is unequivo- 
cal. It wassimultanteously, yet independently, detected by Dr. 
Endlich and myself, in a small specimen from the collection 
made at the mine last summer, and now forming part of the 
Smithsonian Collection in Washington. It did not exist in the 
collection of those ores sent to me by Prof. Hill. The hex- 
agonal cleavages are perfect, and one small and very perfect 
crystal was found, which has been measured by Mr. E. S. Dana. 
Its reactions before the blowpipe are perfectly in accordance 
with those of the species. It contains no selenium and only a 
trace of gold. 
Auriferous Hessite—This mineral has been spoken of as 
petzite; but it contains much too little gold for this latter 
species.* Its sp. gr. is 8°6; luster splendent metallic when 
freshly broken; fracture conchoidal, brittle, but somewhat 
malleable; under the pestle laminates into thin scales, and is 
with difficulty reduced to fine powder, leaving on the agate sur- 
faces metallic streaks of plumbago-like color. Color telluric, 
tarnishes blackish on exposure, sometimes iridescent. Cleavage 
one. 
Before the blowpipe in the closed tube, the pure mineral 
(with no trace of pyrite) decipitates, fuses to a globule adhering 
to the glass, and exhales a white sublimate, fusing into clear 
colorless globules. Alone on coal in both flames it gives a 
globule, coats the coal with the characteristic areola of tellurium 
and tellurous acid; it does not exhale any odor of selenium, nor 
show any trace of lead. The globule is non-magnetic if a 
is absent, and does not vegetate with silver as hessite does ; 
* Mr. A. Kilers, M.E., in a notice of the Red Cloud Mine, in the Transactions of 
the American Institute of Mining Engineers, vol. i, p. 315, considers it te. 
