Copper Mines. - 283 
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_ tinuance of operation ; although in the county of Wicklow, 
enough pure gold was discovered about a century ago, to 
induce Government to expend no small sum in ascertain- 
ing the probability of its being extracted to advantage ; 
and the writer of this statement has seen a piece of native 
gold from Wicklow, as large as half a walnut, but the mine 
was closed after being worked a few years, during which it 
is said that the profit was not equal to the expense of opera- 
tion. 
Of silver perhaps, no mine has been yet discovered in 
this country where that mineral exists in a pure state; it 
is frequently found mixed with other metals, in no incon- 
siderable proportion, though not in snfficient quantity to 
justify its being separated by the furnace. 
Copper is found in Ireland, North Wales, Staffordshire 
and Cornwall, and is associated with rocks of different 
kinds, as also with clay state. 
As the grain or layer of all rocks run east and west, so 
the veins of copper are always found to run in the same 
direction; except where the uniformity of the earth has 
been destroyed by volcanic convulsion, or other disruption, 
occasioning transverse fissures, or turning the direction of 
the stratum. These interruptions are of a very partial 
nature, when compared to the great extent to which the 
veins of mineral are believed to run, supposing their course 
could be pursued; but it generally happens that either a 
mountain, a bog, a river, or an arm of the sea, is found to 
intervene, and preclude the continuance of research. 
The veins of copper differ so much, that it would be im- 
possible to mention any dimension which could be adopted 
as anaverage of their width or thickness. A vein at its 
commencement, is often no thicker than the blade of an 
ordinary knife; but upon being pursued it is found to in- 
crease, sometimes gradually, sometimes suddenly in size, 
until it swells to a width of several feet, and not unfre- 
quently as much as forty or fifty feet. A vein of magni- 
tude is called a /ode, or leading vein, from which minor ones 
diverge at different intervals and angles, but having more 
or less the same direction; and it is observable that the 
course of mineral veins is seldom uniform for any con- 
tinuance. They vary as they proceed as well in quality 
and richness as in bulk, exhibiting ore occasionally in beds 
(or, asthey are termed, bunches), without which the excava- 
tion would be frequently not worth pursuing ; for the chief 
expense of mining, consists in the removal of the stone, 
