362 On the Bristol Copper Mine. 
The linear extent of ground known to ae a by 
excavations made at various times, is between 1100 and 1200 
feet. ‘The principal workings are, however, cofesntratéd in a 
space of about 600 feet north and south. There is good reason 
_. to believe that the metalliferous ground does extend at least 1500 
feet, and perhaps considerably further. The mine is opened to 
the depth of 40 Daihentts (240 feet) by an engine shaft, 6’ x 8’ in 
dimensions, sunk in the sandstone, and passing out of this rock 
into the great ore-channel at this de pth. ‘This is at present the 
only working shaft of the mine, and is used for hoisting ans ore, 
for the pit-work, and as a ladder-road to the levels. The 
of the ore-ground from east to west, or at right angles to she Tine 
of contact, at the engine shaft, as exposed in the cross-cuts and 
levels which have been driven, is about 120 feet, and this width 
is maintained at the lowest depth yet reached in the mine, and 
the same is true for a longitudinal extent of about 500 feet, 
although it appears from the examination of the workings and 
what is known of their history, that the greatest concentration of 
oe matter was on the surface in the vicinity of the 
engine s 
The caifeaee of the ore-ground or metalliferous belt is ex- 
ceedingly complex. 
p to a recent period, however, the workings were chiefly in 
a series of micaceous and hornblende slates, sometimes passing 
into gneiss, and es large irregular “ horses” of granite, 
vhich rock ap ve formed segregated masses, lying 
rudely parallel with the bedding of the schistose rocks. The 
strike and dip of these, ho owever, is found throughout the mine to 
be very irregular, and there j is evidence in the confused character 
of the ground, as well as in the slip joints and polished pssie a 
of the rocks, that motion of the various beds upon one another 
has taken place along lines of upheaval of limited pale and 
varying direction. ‘The distribution of the ores in the metallif- 
erous ground now under consideration, is found to be as irregular 
as is the structure of the ground itself, They consist principally 
of the vitreous, with some variegated ore, and a comparatively 
small amount of copper pyrites. ‘The magnificent erystalliza- 
tions foiand at the Bristol mine, especially of the hea Beth 
have given the locality a world-wide celebrity among min 
gists. In general these ores are found occurring in eer pe 
strings, which although preserving, usually, an approximate pat- 
allelism to the line of contact of the formations, cannot be traced 
continuously for an considerable distance. Hence the irregu- 
others Sot to exist in certain directions, without ery par 
ticular — or = came conceived plan. ‘T'his has been the 
