60 
ANALYSES OF ROCKS, IT. S. GEOLOGICAL SURVEY. 
[NO. 228. 
F. Sericite-schist, Ladiesburg. Described by Bayle/y in Bull. 150, 
p. 317. Contains quartz, sericite, chlorite, a mineral thought to be 
kaolin, zircon, iron oxide, and rutile. Analysis by George Steiger, 
record No. 1600. P. R. C. 126. 
G. Another sample of F. Analysis by Schneider, No. 1370. 
H. Metarhyolite, south of Port Deposit. Dike. Vulcanose. 
Described by F. Bascom, in Maryland Geological Survey, Cecil 
County volume, p. 136. Contains quartz, orthoclase, plagioclase, 
biotite, and hornblende, with accessory magnetite, apatite, titanite, 
garnet, pyrrhotite, and muscovite, and secondary chlorite and epidote. 
Analysis by W. F. Hillebrand, record No. 1928. . 
F. 
G. 
H. 
Si0 2 
57. 24 
• 23. 48 
3.19 
4.87 
.93 
.09 
1.18 
3.55 
.33 
4.65 
.08 
.09 
none 
58. 11 
21.84 
2. 62 
5. 63 
1.85 
none 
.97 
3.66 
.35 
4.05 
.81 
.21 
.19 
75.67 
A1 2 3 .. 
12.28 
Fe 2 3 
a . 85 
FeO 
a 2. 51- 
MgO 
.37 
CaO 
2. 65 
Na 2 O 
3. 63 
K 2 
.78 
H 2 at 100° 
.12 
H 2 above 100° 
.29 
Ti0 2 
.29 
P 2 5 
.05 
MnO 
.18 
SrO 
trace'' 
BaO 
.07 
C0 2 
S 
. 1 1 
99.68 
100. 29 
99. 93 
Uncertain because sulphides are present. 
