214 
ANALYSES OF ROCKS, IT. S. GEOLOGICAL SURVEY. [no. 228. 
K. Pyroxene-andesite, west end of Butte Mountain, Plumas County. 
Hessose. Prominent phenocrysts of pyroxene and minute ones of 
plagioclase, in a dark groundmass containing much globulitic matter. 
Analysis by AY. F. Hillebrand, record No. 41 1. 
L. Pyroxene-andesite, south base of Burney Butte, Shasta County. 
Tonalose. Numerous small phenocrysts of plagioclase and a few of 
pyroxene, in a gray groundmass containing much amorphous matter. 
Analysis by R. B. Riggs, record No. 684. 
M. Hornblende-andesite, Tuscan Buttes, 7 miles east of Red Bluff. 
Tonalose. A few small phenocrysts or fragments of hornblende, in a 
groundmass consisting mainly of plagioclase and gray microlitic 
m itter. Analysis by Hillebrand, No. 412. 
N. Hornblende-andesite, near Buntingville, Lassen County. Lassen- 
ose. A few phenocrysts of hornblende, in a groundmass consisting 
mainly of small feldspars. Analysis by T. M. Chatard, record No. 
413. 
O. Hornblende-andesite, northwest summit, head of Burney Creek, 
Shasta County. Tonalose. Inconspicuous plagioclase and, rarely, 
olivine, in a groundmass of plagioclase and pyroxene. Numerous 
dark spots are due to altered hornblende. Analysis by Riggs, No. 683. 
Rocks in this group dried at 105° before analysis. 
SiO,. 
A1 2 :; 
FeA 
FeO . 
MgO 
GaO . 
Na 2 
K 2 . 
H,< . 
Ti(;_. 
p 2 o 5 . 
Mn( ) 
SrO . 
BaO. 
Li 2 
S0 3 . 
K. 
55.53 
17.63 
2.81 
3. 59 
5. 85 
8.74 
3. 09 
.92 
1.24 
.56 
.21 
.08 
.06 
.02 
none 
100. 33 
62. 44 
L6.39 
4.66 
1.00 
2. 65 
6.22 
3.16 
2.25 
1.02 
.31 
.05 
trace 
trace 
.03 
trace 
trace 
100. 18 
60.93 
L8.56 
2.68 
2.19 
2. 37 
6.63 
3. 79 
1 . 33 
.90 
.61 
.18 
.10 
.12 
.02 
none 
\. 
67.89 
17.29 
2.39 
.21 
.m 
3.01 
5.11 
1.69 
1.34 
.21 
.12 
.12 
.04 
.03 
100. 41 100. 11 
60.04 
17.43 
5.39 
.53 
3. 51 
6.65 
4.15 
1.24 
.90 
.49 
.04 
.08 
CO 
.04 
trace 
trace 
100. 49 
