46 
ANALYSES OF ROCKS, IT. S. GEOLOGICAL SURVEY. 
[no. 
2. MISCELLANEOUS ROCKS. 
A. Peridotite, from Dewitt, near Syracuse. A rock described by 
Darton and Kemp, Amer. Journ. Sci., 3d series, vol. 49, p. 456. Con- 
tains olivine, partly serpentinized, biotite, and augite, with magnetite, 
apatite, and perofskite, Possibly a little chromite also. Classed by 
Kemp as limburgite. P. R. C. 296. 
Analysis by H. N. Stokes, record No. 1491. The FeO represents 
the total iron, because the sulphides present, possibly as pyrrhotite, 
prevent the separate estimation of the two iron oxides. 
B. Syenite, Fort Ann, Washington County. Adamellose. Con- 
tains orthoclase, microperthite, hornblende, green augite, and a little 
quartz. 
C. Quartz-biotite-garnet gneiss, Fort Ann. Consists essential^ of 
quartz, garnet, biotite, orthoclase, some plagioclase, and zircons. 
B and C were collected by J. F. Kemp, who supplies the petro- 
graphic data. Analyses by W. F. Hillebrand, record No. 1930. 
Si0 2 .. 
A1 2 3 
FeA 
FeO.. 
MgO. 
CaO.. 
Na 2 0. 
K 2 0.. 
Ti0 2 . 
Zr0 2 . 
CO,.. 
PA - 
s .... 
so 3 .. 
Cr 2 3 . 
NiO.. 
MnO. 
BaO.. 
SrO_. 
Li 2 . 
0=S, 
36. 80 
4.16 
8.33 
25.98 
8.63 
.17 
2. 48 
.51 
6.93 
1.26 
2.95 
.47 
.95 
.06 
.20 
.09 
.13 
.12 
trace 
100. 22 
.47 
99.75 
B. 
64.47 
10.51 
1.11 
7.37 
5.21 
3.10 
2.21 
3.63 
.18 
.75 
. 65 
none 
.58 
.25 
.12 
trace? 
.04 
.15 
.04 
trace 
none 
100. 37 
.06 
100. 31 
65.09 
16.37 
.93 
5.64 
2.40 
2.40 
3.31 
1.93 
.13 
.58 
.93 
.01 
.07 
.11 
.03 
trace 
trace 
.16 
.03 
trace 
trace 
100. 12 
