20 
CONTRIBUTIONS TO MINERALOGY. 
[BULL. 262. 
It is preferable to regard iron as in the ferric rather than the fer- 
rous state; otherwise an equivalent amount of vanadium would have 
to be considered as V 2 5 , for which there is no occasion. It is quite 
possible that the iron is in part, if not wholly, foreign to the green 
matter, for it would be surprising to find an exposed sandstone free 
from ferric oxide. 
If the iron is disregarded as probably extraneous, the ratios given 
below afford the following empirical formula: 
H QO „ R' 
U1 ? -"^ae ^ m ft 39 ^ 610 
194 
R 
194 
R 
R" Ti'" 
11 39 "^ 610 
R" 
^763 ^2775* 
(Si0 4 ) 565 (Si 3 o 8 ), 
Simplified, this is H 4 
In view of the fact that the mineral is probably not perfectly pure 
and of the uncertainties affecting the amount of water to be considered, 
etc., the above affords a close approach to the typical phengitic mus- 
covite formula, H 2 KR'" 3 X 3 , in which X comprises the groups Si0 4 ! 
and SLO e . 
Soluble in nitric acid: 
Si0 2 
Ti0 2 
VA 
ALA 
Fe 2 3 
CaO 
BaO 
MgO 
K 2 
Na 2 
H 2 C) at 105° 
H 2 at 105°-300° . 
11,0 above 300° .. 
U0 3 
PbO 
v 2 o 5 ..., 
Insoluble in nitric acid 
Quartz, etc 
H 2 at 105° 
H 9 above 105° .. 
Sandstone. 
12.56 
.02 
« 3. 50 
6.15 
.20 
.12 
.37 
.25 
2.41 
.06 
.54 
.14 
.97 
.05 
.06 
.05 
l> 72. 24 
.04 
.20 
99.93 
Ratios. 
0.763 
305 
039 
097 
198 
Silicate. 
46. 06 
12.84 
22. 55 
.73 
.44 
1.35 
.92 
8.84 
.22 
1.98 
.51 
3.56 
100.00 
Roscoelih 
45.17: 
.78' 
24. 01 1 
11.541 
FeO 1.6( 
l.ft 
10.3'; 
.01 
.4f J 
.1 
4.1:1 
99.8 
"Oxidation by permanganate of the HF1 and H0SO4 solution of the sandstone indicated 3.43 pi ' 
cent V0O3 (mean of 3.60, 3.32, 3.48, 3.43). 
b Containing about 65 per cent Si0 2 , 7 per cent A1 2 0. { (Fe 2 3 Ti0 2 ) and about 0.3 per cent of zircc 
and other minerals not decomposed by repeated evaporations with HF1 and H 2 S0 4 . 
Traces of Li, Cu, Mo, Bi. No CI, S0 3 , or P 2 5 . 
