68 
ANALYSES OF ROCKS, U. S. GEOLOGICAL SURVEY. 
[NO. 228. 
2. CRITTENDEN COUNTY DIKE. 
A mica-peridotite, described by Dillerin Amer. Journ. Sci., 3d series, 
vol. 14, p. 286. Contains biotite, serpentine, and perofskite, with less 
apatite, muscovite, magnetite, calcite, chlorite, and some other second- 
ary products. P. E, C. ^n). 
A. The rock described by Diller. SB. 1 of casseliase. 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B. An unpublished analysis of probably the same rock, from a shaft 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 No. 965. 
Si0 2 . 
A1 2 3 
Fe 2 3 
FeO. 
MgO. 
CaO. 
Na 2 
K 2 . 
H 2 0. 
Ti0 2 . 
PA- 
Cr 2 3 
MnO 
NiO . 
CoO. 
BaO. 
CI... 
co 2 . 
so 3 .. 
B. 
33. 84 
5.88 
7.04 
5.16 
L'L\ 96 
9.46 
.33 
2.04 
7.50 
3.78 
.89 
.18 
.16 
.10 
trace 
.06 
.05 
.43 
99.86 
34. 50 
14.37 
2.85 
4.46 
21.81 
11.43 
.51 
1.50 
7.14 
77 
.21 
.60 
100. 15 
