1877. | 121 (Genth, 
The analysis agrees with the formula : 
I Ir vi 
Roepe cis Ory 19/4 K1,0 
eS A N S 
or, K, (MgFe) (Al ¥), Si, O,. + 4 H,O 
as will be seen from the calculated per centage. 
GREEN MINERAL FROM COLORADO, ? ROSCOELITE. 
A mineral which is closely allied to, and which may be only a variety 
of roscoelite, occurs in Magnolia District, Boulder County, Colorado, es- 
pecially at the Keystone and Mountain Lion Mines. It has not yet been 
found in a pure state, but only as the coloring matter of quartz which, at 
some parts of these mines, forms the gangue rock of the veins. The 
purest, which I have seen, was in the form of a thin, earthy coating of a 
greyish-green to olive-green color upon calaverite. 
Mr. Theodore Berdell, to whom I am indebted for specimens has re- 
peatedly called my attention to this green quartz, and mentioned that it is 
always very rich in precious metals. 
For the examination of the green mineral, which colors the quartz, about 
150 grammes of the latter were powdered and separated from the metallic 
particles by levigation, as near as possible. 
The metallic particles were found to be a mixture of native tellurium 
and calaverite, containing : 
Native tellurium = 55.4 % 
Calaverite — Bisa. oF 
The green quartz, which was left,.was found on an average of four ex- 
periments to contain : 
Quartz = 79.38 % 
Tellurium, — ti Obe< 
Gold — ROSES 
80.46 % 
This leaves for the ‘‘ green mineral’ about 19.5 % which was adopted as 
the basis for calculation of the results of the analyses. 
In two experiments, made for the purpose of ascertaining the state of 
oxydation of the vanadium, it was found that after making due allowance 
for the oxydation of ferrous into ferric oxide by potassium permanganate, 
the oxygen in the vanadium pentoxide to that of the vanadium oxide in 
the mineral was: 5 : 3 and 5 : 2.88, which leaves no doubt that the vana- 
dium was present as V,O,. 
The water, which was present in small quantity, could not be deter- 
mined with accuracy, because, on ignition, a portion of the tellurium went 
PROC. AMER. PHILOS. soc. xvi1. 100. P 
