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On Sulphurets of Copper from the Canton (Ga.) Mine. 418 
pyrites, with its bands or plates of cubical pyrites, exhibited in 
e lower levéls may, I think, be taken as representing the con- 
percolating the mass, would be in a condition to assist in the 
ormation of other compounds of copper, while the hydrous Le 
oxyd of iron, formed during the same decomposition, woul 
left staining the strata from which the copper has been extracted. 
That the Harrisite and Cantonite were formed from the sulphate 
of copper in solution, is evident from their position at the lower 
limit of decomposition and the fact that they are found under 
no other conditions in the mine. ‘As to the chemical agencies 
by which black oxyd, native copper, and these sulphurets have 
n precipitated, perhaps from the same solution—we have no 
positive evidence. In one case, at least, that of native copper, 
electro-chemical forces have no doubt been in operation As re-. 
gards the sulphurets—since graphite is found coating seams of 
galena the carbon of which was derived from organic matter in 
I think, an expla- 
hation of all the phenomena presented 1 the peculiar oceur- 
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