56 
ANALYSES OF ROCKS, U. S. GEOLOGICAL SURVEY. [no. 228. 
I. Biotite-granite, Sykesville. Tehamose. Contains quartz, feld- 
spar, and biotite, with accessory magnetite, zircon, and apatite. 
J. Inclusion in I, derived from limestone. Yellowish central 
portion. Consists of epidote and quartz, with a little chlorite. 
K. Same inclusion, fine-grained dark outer zone. Quartz, garnet, 
and epidote, with a little magnetite. Feldspar and muscovite in some 
portions. Descriptions b} 7 Keyes. Analyses by Hillebrand, record 
No. 1220, with the same limitations as in the Guilford, Woodstock, 
and Dorseys Run granites. 
Si0 2 .. 
A1 2 3 
Fe 2 3 
FeO. 
MgO 
CaO.. 
Na 2 
K 2 0.. 
H 2 0. 
Li 2 . 
I. 
J. 
71.45 
67.02 
14.36 
13.77 
2.07 
4.64 
2.78 
1.02 
1.17 
.65 
1.58 
11.09 
1.95 
.66 
3.28 
.09 
1.30 
1.16 
trace 
trace 
99.94 
100. 10 
K. 
47.35 
29.76 
2.94 
3.15 
1.60 
2.20 
2.84 
6.83 
3.15 
trace 
99.82 
