Genth.] 122 {Aug. 17, 
off as hydrogen telluride. In one experiment with the mixture of quartz 
and green mineral 1.24% was found, in a second 0.75—both are too high. 
The following are the results of the analyses of the green mineral, after 
deducting quartz, &c.: 
i: ne ie VE Nis Av’ ge. 
SiO, = 57.15 — 55.77 — — — 57.31 — — 56.74 
Al,O, = 19.94 — — — — 19.46 — 19.46 — 19.62 
V,.0, = 844 — —— — 7.37 — 7.79 — 7.51 — 17.78 
MnO = trace — — — —- — — — — trace 
FeO = 3.51 — — — 452 — — — 3.51 — _ 3.84 
MgO — 2.87 — — — 2.49 — 2.52 — — — _ 2.68 
Li,O| = trace — — = —:— — — — trace 
Nao — 0.94 — — — — —~— — — — — _ 0.94 
KO = 811 — — — — — — — — — 8.11 
H,O = notdet. — — — — — — — —— —not det 
100.96 99.66 
The formula which corresponds nearest to the average analysis is : 
it UR \ yi i 
Ry R, R, Sing OF + xH,O 
1 \ 
Ri Nass hee eo 
Rap ne ee fa 
Sey eee eel 
Or (NaK), (Mg Fe), (Ad ¥), Si, Om + xH,0 
Doubling, for the sake of comparison, the formula of roscoelite we have: 
K, (Mg Fe), (At ¥), Si,, O, + 8 H,0; 
this seems to prove that the green mineral accompanying the tellurium ores 
of the Keystone and Mountain Lion Mines is, although it may be a new 
species, is more probably a variety of roscoelite, in which @ great portion 
of the vanadium is replaced by aluminium. 
9. VOLBORTHITE. 
The Siberian volborthite has never been analyzed. 
Having observed in an experiment which I made with a few frag- 
ments from Woskressenskoi, in the Government Perm, in Ural, received 
from my friend, Prof. Geo. J. Brush, the presence of barium, I communi- 
cated this result to him, when he immediately, with his usual great lib- 
erality and kindness, placed at my disposal for a fuller investigation, all 
he had. I give the results, imperfect as they may be, because they may 
induce others, who have better material for investigation, to repeat the 
analyses. 
The mineral occurred as a crysialline coating on the grains and pebbles 
of quartz, and in the cavities of an argillaceous conglomerate ; it appeared 
to be very pure, of a siskingreen to a greenish yellow color, and of a 
pearly lustre. 
