CLARKE.] 
IGNEOUS AND CRYSTALLINE ROCKS. 
51 
VIRGINIA. 
uk , Andesit a e A K 3 * ? Ues east of Front R °y*l- Described by Keith in 
14th Ann., p. 305 Intermediate between diabase and quart.z-porpb.yrv 
Contains plagioclase quartz, magnetite, ilmenite, and a little epidote. 
Analysis by George Steiger, record No. 1450 
•f W^ yl ^/ el8ite ° r telso ^y^, forks of Straight Creek, 3 
miles ENE. of Monterey. Described by Darton and Keith in Am 
Journ Sci, 4th series, vol. 6, p. 305. Contains phenocrysts of biotite, 
orthockse and plagioclase, the mica and feldspar being about equal in 
amount. In the groundmass are feldspar, quartz, magnetite, oi ilmen- 
ite, and a litt e secondary chlorite with less muscovite. No glass 
Analysis by Hillebraud, record No. 1665. 
A. 
B. 
Si0 2 
51.08 
11.37 
11.17 
5.64 
3.96 
5.20 
5.54 
1.50 
1.31 
.19 
2.67 
.39 
.22 
69.56 
15.52 
1.67 
1.19 
.41 
1.20 
4.46 
4.68 
.34 
.67 
.31 
.08 
.07 
trace 
.10 
trace 1 
none 
(?) 
trace 
A1 2 3 
Fe 2 3 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 OatllO° 
H 2 above 110°.. 
Ti0 2 
PA 
MnO 
SrO 
BaO 
Li 2 
C0 2 
C1,F 
S 
• 
100. 26 
