clarke] IGNEOUS AND CKYSTALLINE EOCKS. 31 
MASSACHUSETTS. 
1. MAGNESIAN ROCKS. 
A. Peridotite, Belchertown. Bdcherose. Described by B. K. 
Emerson in Mon. XXIX. Contains hornblende, pyroxene, biotite, 
olivine, and magnetite. Analysis by L. G. Eakins, record No. 1326. 
B. Wehrlite, New Braintree. Oookose. Description furnished by 
Emerson. Contains diallage, enstatite, augite, anorthite, biotite, 
apatite, chromite, magnetite, and pyrrhotite. Analysis by L. G. 
Eakins, record No. 1327. 
C. Black, serpentinized boltonite, Stow. Collected by Emerson. 
Analysis by W. F. Hillebrand, record No. 1555. 
Si0 2 .. 
A1 2 3 . 
Fe 2 :i 
FeO.. 
MgO . 
CaO.. 
Na 2 . 
K 9 0.. 
H 2 at 100 c 
TiO, 
co 2 . 
p 2 o 5 
Cr 2 3 
MnO 
BaO. 
48.63 
5.32 
2.91 
3.90 
21.79 
13. 04 
.34 
.23 
2.81 
.47 
trace 
.21 
.36 
.12 
trace 
100. 13 
B. 
50.64 
7.93 
1.41 
14.82 
18.58 
3.41 
.96 
.21 
.87 
.82 
05 
Hi 
100. 13 
36.92 
.10 
1.19 
.87 
43. 99 
.59 
.05 
.72 
14. 70 
none 
.90 
trace 
none 
trace 
none 
100.03 
