CLARKE.] 
IGNEOUS AND CRYSTALLINE KOCKS. 
228 
4:. BUTTE COUNTY 
Rocks from this county are also to be found under the heading 
of the Lassen Peak region. The following rocks were collected by 
H. W. Turner, to whom the petrographic data are due. Analyses, 
with two exceptions, by W. F. Hillebrand, record Nos. 1432, 1456, 
1161, and 1518. Analysis G is by H. N. Stokes, record No. 1562. 
A. Granodiorite, north side of south fork of Feather River, oppo- 
site Enterprise. Lassenose. Described in 11th Ann., p. 111. Con- 
tains plagioclase, potash feldspar, quartz, hornblende, brown mica, 
and accessory minerals. The ferromagnesian minerals are largely 
altered to chlorite. P. P. C, 720. 
B. Granodiorite, 2 miles east of Bangor. Tonalose. Composition 
like A. The mica is largely altered to chlorite. See 11th Ann., p. 
111. P. R. C. 717. 
C. Diorite, South Honcut Creek. Beerbachose. Description sup- 
plied by Turner. Contains feldspar, probably all plagioclase, blown 
hornblende, and a little chlorite. P. R. C. 775. 
D. Quartz-dioritc, 1.6 miles south of Table Mountain, on ridge 
between Butte and Plumas counties. Oamptonose. Described in 17th 
Ann., Parti, p. 521. Contains hornblende, feldspur, quartz, rutile, 
and a little secondary chlorite and epidote. P. R. C. 758. 
E. Amphibole, separated from E. Analysis by William Valentine, 
record No. 1723. Cr 2 3 determination by Hillebrand. 
A. 
B. 
C. 
1). 
]•:. 
ti0 2 
70. 36 
15.47 
63. 43 
14.20 
57.87 
16.30 
54.64 
12. or, 
50.08 
A1 2 3 - 
7.07 
Fe 2 3 - 
.98 
1.54 
1.71 
1 si 
2.69 
FeO 
1.17 
.87 
3. is 
4. 91 
4.56 
2. 35 
5.51 
3.49 
3.86 
5. 50 
5.53 
5.01 
5. 03 
11. so 
7.74 
2. 35 
6.71 
MgO 
16. 31 
CaO 
11.21 
Na 2 _ 
1.22 
K 2 .. 
1.71 
2. 10 
.75 
1.01 
.46 
H 2 at 100° 
.06 
.15 
.26 
.12 
lo above 100° 
1.00 
1.50 
2.40 
2.44 
1.40 
TiO, 
.20 
.11 
.73 
.11 
.53 
.27 
.61 
.08 
.76 
PA 
trace 
VA 
.03 
CrA 
.16 
NiO 
.05 
.13 
MnO 
trace 
. 03 
.OS 
.49 
SrO 
trace 
trace 
trace 
trace 
BaO 
.00 
.06 
.05 
. 05 
none 
Li 2 
trace 
none 
trace 
trace 
100. 08 
99.85 
100. 12 
100. 01 
100.40 
