. 
) 
F. A, Genth—Contributions to Mineralogy. 317 
occurs in scajes. The largest of those which I received was 
about ! of an inch in diameter and about ;'; of an inch in 
thickness. Some of the scales showed the lateral planes of a 
six-sided prism. Color between lead and steel grey. It was 
partly oxydized into a substance, which proved to be a new 
mineral, a tellurate of bismuth, for which I propose the name 
“ Montanite.” 
For the analysis, both of the tetradymite and montanite, 
a weighed quantity of the mixed minerals was treated wit 
dilute warm chlorhydric acid, which leaves the tetradymite 
unacted upon, whilst the montanite is easily dissolved by it. 
The specimen was found to contain : 
Tetradymite: i. (oe Seu 49°23 
ins nite - 50°17 
100. “700.00 
II. The ead from the Pheenix mine, of which I 
never have seen more than the one specimen in my collection, 
occurs in very minute scales, the largest not being over ,'; of 
an inch in width, of a color ‘between lead-grey and iron-black 
implanted and cian are in quartz and associated wit 
gold and pyrites. From the analysis was deducted 86°71 p. c. 
ld. 
The following results were obtained : 
I (Montana.) II (Pheenix Mine). 
Quartz, 0-78 Copper, 0°41 p.c. 
Ferric oxyd, 0°90 Iron, 0°54 requires 0°61 sulphur. 
Bismuth, 50°43 57°70 
Tellurium, 47°90 36°28 
Sulphur, none 5°01 
100°01 99°94 
The ratio between bismuth and tellurium in I. is dng ~ 
=1: 3, which places this tetradymite alongside of those fro 
Fluvanna Co, , Va., and Field’s mine, Georgia. 
In analysis IL. isa slight admixture of pyrites. The requi- 
site quantity of sulphur for the amount of iron found, is=0°61, 
leaving 4-40 p. c. of sulphur as a constituent of the ead 
mite. The ratio between sulphur, tellurium and bismu 
d':.2-08 +1, gi exactly the formula BiS,+2BiTe,. 
Admitting with Gustav Rose that tellurium sometimes re- 
laces bismuth, as in the native bismuth from the Sorato, the 
bismuthine from Riddarhyttan, and the mineral = Cumber- 
land, England, analyzed by Rammelsberg, which contains 6-43 
“S 
p. ¢. of sulph nal to 28°13 c. of BiS,, sowing ite 
suiphur, eq Pp. remeyse : 
a mixture of bismuthine and native bismuth, 
= 
Fie ck 
£ Sekai» 
