215 
Geological Relations of the East of Ireland \ 
white clay. When brought to the surface and exposed to the 
influence of the atmosphere, these substances undergo rapid decom 
position and enter into new combinations, forming sulphate of iron, 
sulphate of copper, alum, and oxide of iron. Similar combinations 
take place also below ground, where moisture and a circulation of air 
prevail through the subterranean workings; and water percolating 
through these, it becomes charged with the metallic salts. 
In a bed of this soft ground are contained one or more layers 
parallel to each other of copper pyrites, or mere iron pyrites, varying 
in thickness, and sometimes acquiring a breadth of several fathoms.. 
Five such beds of soft ground have been met with, one in Connery, 
two in the old or upper mine of Crone-bane, one in the new or lower 
mine, and one in Tigrony. In the map of these mines, I have 
distinguished their several positions by a bluish grey colour; (see 
Plate 12.) That in Connery contains a bed of ore about four feet 
thick, consisting of a fine grained intermixture of galena, grey ore of 
antimony, and blende, with pyrites of copper, iron, and arsenic. 
These constitute together a very hard and firm compound ; but as 
no one metal predominates in any considerable degree, the working 
of it has not been attended with advantage. A similar compound 
occurs in the second and more southern bed of the upper mine in 
Cronebane, being found in its north-eastern prolongation, where it 
is crossed by the Lodge Level. The more northern bed contains 
much iron pyrites, and it has yielded at different periods some thou- 
sand tons of black copper ore, which in the greater depths of the 
mine passes into copper pyrites. It was on the outcrop of this bed 
that the oxide of iron occurred, which yielded auriferous silver. 
The third bed in Cronebane, situated in the western flank of the 
hill, has proved the most valuable, the greater part of its width being 
occupied by copper ore, which in the upper part consisted princi- 
