CLARKE.] 
IGNEOUS AND CRYSTALLINE ROCKS. 
179 
2d dacites and andesites. 
A. Gra}^ dacite, Lassen Peak. Contains hornblende, biotite, plagio- 
clase, quartz, scarce pyroxene, magnetite, apatite, and a glassy base. 
Analysis by T. M. Chatard, record No. 111. P. R. C. 82. 
B. Secretion in dacite, Lassen Peak. Composed chiefly of plagio- 
clase and hornblende. Analysis by Chatard, No. 110. 
C. Reddish dacite, Lassen Peak. Essentially like A. Analysis by 
Chatard, No. 110. P. R. C. 82. 
D. Dacite, near the timber line, west base of Lassen Peak. Small 
phenocrysts of plagioclase and hornblende, with a few of quartz, 
in a reddish-gray groundmass containing much amorphous matter. 
Analysis by W. F. Hillebrand, record No. 668. P. R. C. 82. 
E. Secretion in D. Composed essentially of plagioclase and horn- 
blende. Analysis by Hillebrand, No. 669. P. R. C. 82. 
Rocks A, C, D, and E described by Diller in Bull. 150, p. 217. 
A. 
69.51 
15. 75 
3.34 
B. 
C. 
68.20 
16.98 
3.75 
D. 
68.32 
15.26 
1.66 
1.26 
1.32 
3.26 
4.27 
2.81 
1.37 
.31 
.12 
.04 
trace 
.07 
trace 
E. 
Si0 2 
58.97 
18.60 
5.94 
55.14 
. 19. 10 
6.16 
.54 
4.23 
8.36 
3.71 
1.04 
.91 
.52 
.18 
.11 
.07 
trace 
trace 
A1 2 3 
Fe 2 3 
FeO 
MgO 
2.09 
1.71 
3.89 
3.34 
.56 
6.89 
2.84 
3.05 
2. 24 
1.35 
2.07 
4.33 
2.98 
1.52 
.44 
CaO 
Na 2 
K 2 
H 2 
Ti0 2 
P,0, 
trace 
undet. 
MnO 
SrO 
"BaO 
Li 2 
100. 27 
100. 19 
99.88 
100. 07 
100. 07 
