168 
AMERICAN GEOLOGY. 
When it unites with the vertical vein it swells out to a width 
of seven or eight feet. It carries also a quantity of iron py¬ 
rites which is silver white. It has not been analyzed, but 
probably contains arsenic and cobalt. Among the remarkable 
veins of the south, those of Ducktown, Polk county, in Tennes¬ 
see, have probably excited the most attention. The rock is a 
talcose slate, interlaminated with hard layers of gneiss and 
hornblende, and highly inclined. There is nothing in the 
general appearance of the country which indicates a mining 
region, and accident alone brought to light the remarkable 
repositories of copper ore. The ores of this district are in 
some respects unlike those of North Carolina: they are arse¬ 
nical, and probably to the presence of a third metal the peculiar 
condition of the copper ore is due. 
A section of the Congdon vein at this place, gives all the 
information we desire respecting this structure. 
The section is vertical and 
longitudinal for the purpose 
of showing the slope or pitch 
of the materials of the lode, 
for it has a slope in addition 
to its dip. The following 
exhibits the order of arrange¬ 
ment: 1, talcose slate; 2, 
Gossan, or hydrous peroxide 
of iron; 3, bell metal ore; 
4, black oxide of copper; 5, 
1 Talc Slate, 2 Gossan, 3 Bell metal, masses indicative of the 
4 Black oxide of Copper, 5 Mundic. 
commencement of the yellow 
sulphuret or mundic. The Gossan was seventy feet thick in 
the direction of the shaft sunk upon a hill. It is destitute of 
copper in the upper part of the mass, but it is present in the 
lower. The bell-metal ore is only from twelve to sixteen inches 
thick, and the thickness cf the black oxide is variable in con¬ 
sequence of resting upon an uneven floor, but exceeded three 
feet. The width of this vein at the surface is five feet, with its 
