CLARKE.] 
IGNEOUS AND CKYSTALLINE ROCKS. 
55 
GEORGIA. 
Rocks collected by A. H. Brooks, who supplies tne petrographic 
data. Hitherto unpublished. Analyses by H. N. Stokes, record No. 
1727. 
A. Meta-quartz-diorite, 2 miles southwest of Sweden, Gordon 
County. Contains plagioclase, near labradorite, green hornblende, 
sometimes diallage, much vitreous quartz, and accessory magnetite, 
ilmenite, and orthoclase. Also secondary epidote, zoisite, uralite, 
chlorite, garnet, calcite, and leucoxene. 
B. Augite-microcline-granite, 1 mile east of Rowland, Bartow 
County. Contains microcline, some plagioclase, abundant pyroxene 
partly altered into chiefly uralite and chlorite, some biotite with fre- 
quent inclusions of rutile, much blue vitreous quartz, apatite, zircon, 
and magnetite. 
C. Quartz-gabbro, 2 miles southeast of Walleska, Cherokee County. 
Closely related to B. Contains essentially plagioclase, near labrador- 
ites, and augite. Accessory magnetite, ilmenite, apatite, and zoisite. 
Orthoclase is sparingly present. Quartz occurs in vitreous masses. 
Si0 2 
aia 
Fe 2 3 
FeO 
MgO.. 
CaO 
Na 2 
K 2 
H 2 OatllO°.... 
H 2 above 110 c 
Ti0 2 
P 2 5 
MnO 
BaO 
SrO 
Li 2 
co 2 
s 
so 3 
CI 
F 
C (graphite) ... 
69.87 
12.02 
1.42 
3.49 
2.30 
7.86 
.66 
.11 
.18 
.89 
.69 
.17 
.-16 
none 
none 
trace 
.43 
none 
none 
none 
(?) 
100. 25 
B. 
67.98 
14.84 
1.00 
3.15 
.91 
2.17 
2.66 
4.76 
.14 
.49 
.84 
.34 
trace 
.20 
trace 
trace 
none 
.08 
trace 
trace 
trace 
.21 
99.7- 
56.20 
15.46 
1.54 
9.76 
1.83 
5.39 
2.78 
2.56 
.16 
.59 
2.25 
1.13 
.13 
.17 
trace 
none 
none 
.07 
trace 
trace 
trace 
100. 02 
