508 
COPPER. 
with ill the poorest part of the vein, and generally 
but a little way beneath the ground. The different 
mines in the neighbourhood of Rudworth are so con- 
siderable that 578 men are employed ; of whom 
150 are engaged on the surface, and 428 under- 
In the island of Anglesey there is a very rich 
mine which encloses veins of copper of more than 
sixty feet in thickness, and of an unknown depth. 
These beds of mineral were discovered in the year 
1768, among some mountains, in the neighbourhood 
of high and steep declivities, which exhibit enor- 
mous blocks of white and coarse quartz. 
In Ireland , in the county of Wicklow, are the 
mines of Cronebane and of Bally-Murtagh. They 
are enclosed within a mountain composed of primi- 
tive earth, and the copper ore obtained from them 
is sent to Liverpool to be smelted. 
One of the most singular copper-mines in Europe 
is that of Riegeldorff in Germany. It consists of 
veins of copper mineralized by sulphur and mixed 
with bitumen. They are situated under beds of 
chalk, gypsum, marble, and black pyritous slate, in 
which is frequently found the impression of fish. 
Under the bed of metal is a bank of sand impreg- 
nated with copper, and resting on a thick stratum of 
a coarse red sand-stone composed of round pebbles, 
of quartz, and of petrosilex. 
The copper-mine of Fahlun, the capital of Dale- 
carl ia, in Sweden , may be ranked among those 
which are considered as the most antient, and at 
