CLARKE.] 
IGNEOUS AND CRYSTALLINE ROCKS. 
71 
D. Rock of basaltic habit, allied to C, 1 mile northeast of Big Moun- 
tain, Uvalde quadrangle. Essexose. Contains alkali feldspar, augite, 
magnetite, and variable amounts of olivine, nephelite, segirite, biotite, 
and zeolitic minerals. Sp. gr., 2.742, 23°. P. R, C. 1068. 
SiO,.. 
A1 2 3 - 
FeA 
FeO.. 
MgO. 
CaO.. 
Na 2 0. 
K.,0 . 
H 2 above 110 c 
Ti0 2 
PA 
Zr0 2 
OA- 
VA ■ 
MO.. 
MnO. 
SrO. 
BaO . 
S0 3 
CI 
Less O . 
68.71 
13. 45 
5.31 
.75 
.19 
.96 
4.63 
5.51 
.13 
.36 
.21 
.04 
.14 
none 
none 
none 
05 
100. 44 
45. 11 
« 1 2. 44 
2.67 
9.36 
11.56 
10.61 
3. 05 
1.01 
.16 
.78 
2.34 
.51 
(?) 
.04 
.04 
.22 
trace 
trace 
none 
.01 
.11 
tindet. 
100. 02 
.02 
100. 00 
48.13 
18.44 
3. 41 
4.30 
3.06 
5. 89 
8.00 
3. 80 
.18 
1.59 
1.74 
.49 
.05 
none 
.02 
.19 
.10 
.10 
trace 
29 
06 
i). 
99. 93 
.09 
99. 84 
48.23 
17.43 
2.77 
5.92 
2.99 
6. 38 
6. 87 
2. 78 
.54 
2. 84 
2.00 
.69 
.04 
none 
.04 
trace 
.18 
.08 
.08 
trace 
.08 
.03 
undet. 
99.97 
a Including Cr._.() :i 
