CLARKE.] 
IGNEOUS AND CRYSTALLINE ROCKS. 
49 
To these may be added three analyses of feldspars from the pegma- 
tite of Jones Falls, Baltimore. Described by S. L. Powell in Johns 
Hopkins Univ. Circular, vol. 12, p. 49. Analyses by W. F. Hillebrand, 
record No. 1421. 
O. Flesh-colored microcline. 
P. Green microcline. 
Q. Albite-oligoclase, near Ab 4 An. 
Si0 2 
A1A 
FeA 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 Oatl00°... 
H 2 above 100 
SrO 
BaO 
65. 06 
18.41 
trace 
.04 
.26 
1.60 
14. 30 
.04 
.26 
trace 
.13 
100. 10 
68. 48 
16. 11 
.20 
.17 
.03 
.23 
1.27 
12. 99 
.06 
.26 
trace 
.05 
99.85 
Q. 
63.72 
22.26 
trace 
.06 
3.58 
8.98 
.76 
.09 
.43 
trace 
88 
P contained a little unseparated quartz. All three contained traces of lithia. 
O and Q the traces of iron were weighed with the alumina. 
In 
Bull. 168- 
