214 Scientific Proceedings, Royal Dublin Society. 
Tigroney brow, both have been removed by denudation, and the 
iron pyrites (sulphur ore) comes up to the surface. The gossan 
in West Cronebane is found in places to rest on beds of ferrugi- 
nous clay; and in one place I have found black carbonaceous 
clay, resembling the “coal ground” of the Magpie, at the foot- 
wall; generally, however, the gossan is found to rest upon soft 
steatitic slaty clay, containing strings and bunches of melaconite 
and fahlerz, with small leaves of iron pyrites, and occasional veins 
of the same in a granular state, composed entirely of small loose 
crystals of pyrites; but in depth this “sand ore” loses these char- 
acters and becomes compact. In depth the thin leaves of pyrites 
rapidly increase in number and thickness, cutting out the inter- 
vening leaves of killas, until, eventually, the entire width of the 
lode is filled with more or less fissile iron pyrites. Still deeper 
the iron pyrites becomes more compact and interlaminated with 
hard killas ; under the latter circumstances the hardest ribs gen- 
erally contain 2 per cent. of copper. 
Previous writers have not drawn attention to the smooth hori- 
zontal joints (“beds” or “floors”) in the lode which occur at 
intervals of 1 to 1:5 fms. in depth, some of them being continu- 
ous for 8 fms. in length, and always being the entire width of the 
lode, but in no case are they known to extend into the adjoin- 
ing country. These “beds” divide the ore into tabular masses, 
which are crossed in places by two systems of obliquely standing 
joints which subdivide the mass, and occasionally form triangles. 
These are of great importance to the miner, as when one of these 
triangles is cut away a large fall of ore is obtained, especially 
when there are clayey partings on the walls. 
At the Copse shaft the sulphur Jode is cut out in depth by the 
westward underlie of the “Dead Ground ” (cross section No. 5) ; 
but elsewhere it has not been proved to its full depth. 
Seventy fms. east of Williams’s shaft the lode is 8 fms. wide at 
surface (cross section No. 2), decreasing to 6 fms. at the 77-fm. level, 
below which it is suddenly cut off by a slide underlying south 
at 45°. This slide was sunk on for 13 fms., and a well-defined 
vein of cupreous sulphur ore, 2 fms. wide, found, the walls of 
which are opening in depth. This sulphur ore has not been 
proved below the 90-fm. level, which is the deepest point reached 
in any of the eastern Ovoca mines; this remarkable displace- 
