50 
CONTRIBUTIONS TO MINERALOGY. 
[BULL. 262. 
as the seams, but impure and mixed with a little chlorite and pyrite. 
The whole bears evidence of being a product of oxidation of some 
contact metamorphic mineral. 
The fibrous mineral on the seams forms a felted aggregate as seen 
under the microscope, but it is well individualized and contains few 
impurities except a little pyrite and chlorite. The minute fibers are 
brownish yellow and slight^ pleochroic, being darker when parallel 
to the principal section (opposite the behavior of biotite); the bire- 
fringence is strong and extinction strictly parallel to the fibers. No 
mineral corresponding to this has been described, but, although its 
individual character is beyond doubt, the analysis does not lead to a 
satisfactory formula. The material for the analysis was picked out 
carefully under the lens and examined under the microscope it proved, 
satisfactorily pure. 
The analysis afforded the results of the first column of figures below. 
In deducing the molecular ratios of the second column there has been 
deducted sufficient lime to form apatite with the phosphoric oxide. 
Molecular ratios. 
Si0 2 
45. 74 
757 
= 10. 71 or 11 
Ti0 2 
trace 
ALA 
1.98 
019) 
V205 
186) 
Fe 2 3 
29. 68 
= 2. 90 or 3 
FeO 
83 
011^ 
MnO 
trace 
CaO 
MgO 
1.61 
3. 99 
027 
100 
141 
= 2. 00 or 2 
K 9 
20 
002 
Na 2 
10 
001. 
H,0 105° 
8. 84 
491 
= 6. 96 or 7 
H 2 150° 
12] 
H 2 below redness 
4. 27 i 
282 
— 3. 99 or 4 
H 2 redness . 
. 69 J 
CuO : 
little 
FeS 2 
66 
P 2 5 
18 
98.89 
It would seem from the temperatures at which the water is drivei 
off that this must exist in two conditions, and that four-elevenths o 
it must be held more securely than the remaining seven-elevenths 
The attempt to account for four molecules of water as constitutional 
however, led to no simple or seemingly probable formula, whereas i 
all water is excluded the ratio is that of a metasilicate— R" a R'" 
(Si0 3 )" n . On the other hand, to include the whole of the water ai 
essential to the silicate molecule, for which there is little ground ii 
