54 J. D. Whitney on changes in Mineral Veins. 
ore exists in its original condition.” It seems hardly possible 
that any one should ever have supposed the black ore to have te~ — 
sulted from the decomposition of any other part of the vein than 
that which lies above it, as below it everything remains in its 
original, unaltered condition. me 
The decomposition of metalliferous lodes in their superficial 
portions is a matter often noticed and generally expected by the 
miner, and there is nothing anomalous in this respect in the East 
Tennessee Copper region. The commonly observed facts are 
these: the predominating metalliferous ores which are wrought 
in mines, especially of silver, copper and lead, are sulphurets, sul- 
phur being the usnal mineraliser, although, arsenic and antimon 
mp ace 
feet and generally falls between 50 and 00 feet.. This decomp 
character: the oxydised ores are replaced by the sulphurets ; the 
