38 
ANALYSES OF ROCKS, TJ. S. GEOLOGICAL SURVEY. 
[bull. 168. 
2. PERIDOTITE FROM DEWITT, NEAR SYRACUSE. 
A rock described by Darton and Kemp, Amer. Journ. Sci.,3d series, 
vol. 49,' p. 456. Contains olivine, partly serpentinized, biotite, and 
augite, with magnetite, apatite, and perofskite. Possibly a little chro- 
mite also. Classed by Kemp as limburgite. 
Analysis by H. N. Stokes, record No. 1491. The FeO represents the 
total iron, because the sulphides present, possibly as pyrrhotite, pre- 
vent the separate estimation of the two iron oxides. 
Si0 2 
A1 2 3 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 below 100° 
H 2 above 100° 
Ti0 2 
P 2 5 
Cr 2 3 
36.80 
4.16 
8.33 
25.98 
8.63 
.17 
2.48 
.51 
6.93 
1.26 
.47 
.20 
NiO. 
MnO 
BaO. 
SrO. 
C0 2 . 
so 3 . 
s ... 
o=s 
.09 
.13 
.12 
trace 
2.95 
.06 
.95 
100. 22 
.47 
99.75 
