CLARKE.] 
IGNEOUS AND CRYSTALLINE ROCKS. 
41 
Q. Granite-gneiss, Hoosac Mountain. Toscanose. Contains quartz, 
mierocline, albite, muscovite, biotite, magnetite, titanite, epidote, 
apatite, and zircon. Analysis by E. T. Allen, record No. 2064. 
R. Albite schist, Hoosac Mountain. Varingose. Same minerals as 
in Q, with garnet and pyrite. Same analyst and number. 
Rocks Q and R collected by J. E. Wolff, but not yet described. The 
following feldspars, all albite, separated from schists of the same region, 
are described by Wolff, in Mon. XXIII, pp. 60 and 187. Analyses by 
R. B. Riggs, record Nos. 507 and 567. 
S. From feldspathic schist, central shaft of the Hoosac tunnel. 
P. R. C. 129. 
T. U. From the porphyritic mica-schist of Gre}dock Mountain. 
SiO, 
A1 2 3 
Fe 2 3 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 at 105° 
H 2 above 105° 
Ti0 2 
Zr0 2 
PA 
S 
Cr 2 3 
MnO 
BaO 
67.12 
14.97 
2.61 
2.19 
.54 
1.69 
3.92 
5. 15 
.19 
1.13 
.37 
.03 
.14 
none 
trace 
.02 
.19 
100. 26 
70.95 
9.99 
3.08 
6.10 
1.08 
.38 
1.69 
3.74 
.40 
1.82 
.63 
.04 
.23 
.05 
trace 
trace 
.04 
69.69 
I 
18. 60 
100. 22 
.20 
trace 
10.28 
.40 
''.42 
99.59 
T. 
OS 
«20. 11 
(?) 
trace 
11.00 
.36 
i>. 31 
trace 
99.86 
r. 
67.83 
«19.92 
(?) 
trace 
11.65 
.25 
&.12 
trace 
99.77 
aFe 2 O a less than 0.5 per cent. 
&Loss on ignition. 
