354 ANALYSES OF ROCKS, 1 
[T. S. GEOLOGICAL SURVEY. 
[no. 228. 1 
VIRGINIA, NORTH CAROLINA. 
A. Residual clay from decay of Trenton limestone, Lexington, Vir- 
ginia. Described by Russell in Bull. 52. Analysis by R. B. Riggs, j 
record No. 373. See also analysis of the limestone. 
B. Residual clay from limestone, Staunton, Virginia. 
C. Portion of B soluble in weak hydrochloric acid. 
D. Insoluble portion of B. Analyses B, C, and D by George; 
Steiger, record No. 1630. See also analysis of limestone. 
E. Decomposed dolerite, near Wadesboro, North Carolina. De- 
scribed by Russell in Bull. 52. Analysis by T. M. Chatard, record 
No. 327. 
F. Residual clay from decay of chloritic schist, Cary, 8 miles west 
of Raleigh, North Carolina. Analysis by R, B. Riggs, record No. 
364. Described by Russell in Bull. 52. 
A. 
B. 
c. 
D. 
E. 
F. 
Si0 2 - 
43, 07 
25.07 
15.16 
55. 90 
19.92 
7. 30 
.39 
1.18 
3. 09 
3. 96 
6.25 
.30 
.43 
52. 81 
15. 96 
1.05 
.09 
.75 
39. 55 
28. 76 
16.80 
.59 
54. 54 
26. 43 
9. 04 
ALOo 
Fe 2 3 
FeO 
MgO 
.03 
CaO 
.63 
1.20 
.50 
.23 
.30 
.20 
.20 
.03 
.37 
undet. 
Na 2 
K 2 ' 2. 50 
4. 79 
.28 
4.51 
undet. 
H 2 Oat 110° 
I 12.98 
2. 54 
1 13. 26 
| 9. 87 
H 2 above 110° 1 
6.52 
2. 10 
4.42 
Ti0 2 
.20 
. 10 
.04 
.04 
.16 
.06 
.64 
. 10 
P 2 5 
Cr 2 3 
trace 
MnO 
none 
.38 
trace 
C0 2 
.38 
none 
100. 64 
99. 95 
17.37 
80.04 
100. 07 
99. 88 ; 
