weed] COPPER DEPOSITS OF THE APPALACHIAN STATES. 185 
operation, but the ore proves difficult to dress and very siliceous in 
character. 
TENNESSEE. 
The only copper deposits in Tennessee are the well-known Duck- 
town mines, situated in the extreme southeast corner of the State. 
These properties were famous for their rich secondary ores half a 
century ago, were worked at intervals for thirty years, and are now 
in successful operation. The deposits are very large lenticular bodies 
of pyrrhotite or pyrite in mica-schists, shown by Kemp to be meta- 
morphosed shales. No igneous rocks are known near by, and the rocks 
are probably Algonkian. The schists have been broken by disloca- 
tions, along which the ores have been deposited, the ore bodies usu- 
ally conforming very closely in course and dip to the inclosing schists. 
There are two main and parallel lines of fracture. The ore bodies 
are huge lenticular masses of sulphides, several of them 100 feet or 
more thick. The common ore is a mixture of pyrrhotite and chalco- 
pyrite, with calcite, quartz, zoisite, garnet, and in some cases much 
actinolite. In some ore bodies pyrite replaces the pyrrhotite wholly 
or in part. Much of the ore is shattered and sometimes brecciated, 
the chalcopyrite filling the cracks. A second period of shattering 
was followed by the formation of coarsely crystalline pyrrhotite, cop- 
per p3 r rite, and blende. These ore bodies are covered by a gossan 
of porous-textured iron ore, consisting of hematite and limonite, pro- 
duced by the oxidation of the sulphides, which is mined in large 
quantities for iron furnaces. Beneath this gossan occurred the rich 
"oxysulphuret " ore, a loosely textured mass of amorphous copper 
glance, to 10 feet thick, lying above the unaltered sulphide ore. 
This secondary ore is, however, now all extracted, and the copper 
contents of the ore bodies being worked averages about 3.5 per cent. 
