204 The American Geologist. -^p^''- '^^^'^• 
a little muscovite, apatite and zircon are all present. [Plate 
XVIII, figure 2.] 
Chemical Analyses of the Elberton-Echol's Mill Light-Gray 
Granite. 
I. 
II. 
III. 
SiOs 
69.45 
69.25 
68.81 
AI2O3 
15.93 
16.04 
17.67 
FeoOs* 
1.31 
1.72 
1.13 
CaO 
1.91 
1.89 
2.17 
MgO 
0.55 
0.31 
50 
K2O 
5.16 
4.94 
3.90 
NaoO 
4.33 
4.52 
4.97 
Igni 
0.50 
0.43 
0.30 
Total 99.14 99.10 99.45 
I. Biotite granite from Swift and Wilcox quarry, 1 mile south of 
Elberton, Georgia. 
II. Biotite granite from Tate and Oliver quarry in the limits of 
Elberton, Georgia. 
III. Biotite granite from Echol's Mill, 12 miles northeast from Lexing- 
ton, Georgia. 
The Campbell-Coweta-Meriwether Counties' Medium 
Blue-Gray Granite : In addition to the normal massive gran- 
ites, coarsely crystalline porphyritic granites and granitic 
gneisses of essentially the same mineral and chemical composi- 
tion, are found in intima.te association over parts of Campbell, 
Coweta and Meriwetl?^ bounties. 
The even-granular n:^ssive type of granite is of two varie- 
ties. One, the medium gray, is an average fine-textured crys- 
talline rock consisting of anhedra of an average size, 0.5-1.5 
millimetres. [Plate XIX, figures i and 2.] The other, a dark- 
blue-gray, occurs in the southwest section of Meriwether coun- 
ty. [Plate XX, figure i.] It is more coarsely crystalline and 
darker in color and contains a larger proportion of biotite, than 
the medium gray type. 
The medium gray type traverses Campbell, Coweta and 
]\Ieriwether counties, in a nearly north-south course, with 
quarries opened near the respective county seats, Fairburn, 
X^ewnan and Greenville. The variation in color and texture, 
in general, is very slight. The northern part of the granite- 
mass, in the vicinity of Fairburn, is somewhat lighter in color, 
with the middle and southern parts near Xewnan and Green- 
A'ille, correspondingly darker. This type is closely similar in 
mineral and chemical composition to the Oglesby-Lexington 
* .Ml iron estimated as FeaOa. 
