C. U. Shepard on Tetradymite in Georgia. 39 
Figure 5, a twin, is by far the most abundant form, equal- 
ling in frequency all the others combined. It results from the — 
composition of two such forms as e 1. 
plane of composition is coincident with the rhom- 
5. 
ic base of the figure; and the angle of revolution 
=180°. 
The faces of none of these erystals are suffi- 
ciently polished to allow of the use of the re- 
flecti Cd 
ecting gonimeter. 
hig oslo of the lazulite is various shades of <2 4 #2 / 
berlin and indigo blue. The effect of weathering 
is, to lower the intensity of the blue, and rarely 
to give rise to a shade of green. 
Tetradymite in Lumpkin county. 
An important discovery of gold has been made during the last 
summer in the middle of the Chestatee river, four miles east of 
Dahlonega. It occurs in seams in hornblendic gneiss. Accom- 
panying the gold were found considerable quantities of a white 
foliated massive mineral, having nearly the color and lustre of 
tin, which was taken for silver by the miners, though to others 
it suggested the idea of platinum and even of molybdenite. 
Several specimens were forwarded to me for examination by Dr. 
M. F. Stephenson and by W. F. Harris, Esq. I find it to be 
tetradymite, a species I had before observed in small quantities 
along with gold, at the Pascoe mine in Cherokee county, and at 
a place near Van Wort in Polk county. 
From the specimens sent, it appears that the gangue of the 
mineral is gneiss; though in a specimen from Mr. Harris it is 
di in seams through granular white calcite, rendering the 
mass as heavy as barytes, for which substance it appears, on 
this account, to have been mistaken. 
Tn both gangues, it is attended by gold.* A number of speci- 
cimens of the gneiss included with quartz veins, were sent 
to me for inspection. The quartz veins are transverse to the 
Stratification of the gneiss, and vary in thickness from one to 
two inches. They contain irregularly shaped masses of pyr- 
rhotine (intermingled with traces of chalcopyrite), chlorite, an- 
ilar fragments of green hornblendic gneiss, cleavable calcite, 
imenite in broad highly curved crystals, to which may be added 
. few crystals of allanite and grains of yellow apatite <A few 
* As it has a very pale brass-yellow color and assays at the mint only from 717 
to 800, while the deposit gold in the vicinity varies from 910 to 920, it is possible it 
an alloy of gold and bismuth, analogous to the sample I examined several 
_ years ago , N. C., mint, and for which, in the event of its occuring 
nature, I have suggested the name of Bism i 
-_ + This is the only instance in which I 
uthaurite. 
have detected apatite in the Southern states ; 
ere beryl, also, appears to be equally rare. 
