58 
ANALYSES OF EOCKS, U. S. GEOLOGICAL SURVEY. [bull. 168. 
2. THE CRITTENDEN COUNTY DIKE. 
A mica-peridotite, described by Diller in Amer. Journ. Sci. , 3d series, 
vol. 44, p. 286. Contains biotite, serpentine, and perofskite, with less 
apatite, muscovite, magnetite, calcite, chlorite, and some other second- 
ary products. P. R. C. 800. 
A. The rock described by Diller. Analysis by W. F. Hillebrand, 
record No 1241. 
B. An unpublished analysis of probably the same rock, from a shaft 
40 feet deep at Marion. Collected by J. R. Procter, analyzed by L. G. 
Eakins, record number 965. 
A. 
B. 
Si0 2 
33.84 
5.88 
7.04 
5.16 
22.96 
9.46 
.33 
2.04 
7.50 
3.78 
.89 
.18 
.16 
.10 
trace 
.06 
.05 
.43 
34.50 
14.37 
2.85 
4.46 
21.81 
11.43 
.51 
1.50 
7.14 
ALO, 
Fe 2 3 
FeO 
MgO 
CaO 
Na 2 „ 
K 2 
H 2 
Ti0 2 
F<A 
.77 
Cr 2 3 
MnO . 
MO. 
CoO 
BaO 
CI ..-. 
co 2 
.21 
.60 
so 3 
99.86 
100. 15 
