MALACHITE OF NIJNY TAGILSK. 
373 
The ore being worked in shafts, and not like the iron in open quarries, we are 
by no means certain that this rough drawing, which we made when we descended 
the mine, represents the whole case with precision. Our sole object is to show, 
that in a space between ridges of eruptive rock, and bounded by a wall of schaal- 
stein, which is itself to some extent impregnated with copper, a considerable 
mass, in a much more incoherent and broken condition, is the chief mining 
ground 1 . This cupriferous deposit may be nothing more than a broad vein, 
though it seemed more to resemble a slightly consolidated heap of detritus which 
had been tumultuously aggregated in this hollow, at a period of convulsion, 
when the subjacent rocks were invaded by some sort of igneous action, and all the 
strata were broken up and re-arranged. In proof of this, points of limestone, the 
surfaces of which are irregularly eroded, polished and worn into depressions, as 
if by water, protrude from beneath into the matrix of copper stuff, in the manner 
described in the previous sketch. Though nearly all traces of bedding are oblite- 
rated, this limestone is still sufficiently characterized by the large Pentameri which 
it contains, to enable us to consider it of Upper Silurian age. That the copper has 
been accumulated subsequent to the consolidation of the adjacent palaeozoic strata, 
is, indeed, evident ; since, independent of their dislocated condition, rolled pebbles 
of the limestone have been found in the heart of the mining stuff. We were also 
assured by M. Schwetzoff that rounded and rolled lumps of the magnetic iron-ore 
also occur in this cupriferous mass ; a fact which must induce the belief, that the 
agency which developed the copper ore, though probably also connected with the 
evolution of mineral springs, was in play at a different and posterior epoch. 
The copper ground we have been describing having been excavated by shaits, 
an enormous mass of malachite was recently detected at the depth of 2>0 feet. 
Thin strings of green copper ore occurring at intervals were followed downwards, 
when increasing in width and value, they were found to terminate, at the base of 
the present mines, in an immense, irregularly shaped botryoidal mass of solid 
malachite, the form of which, as far as its lower part has been laid open, is repre- 
sented in the preceding drawing 2 3 . 
The base of this valuable mass has not yet been traced, but when we examined 
1 For all the varieties of copper ore and other minerals which occur here, see the work of M. Rose, 
which has completely superseded the faithful but now rather antiquated descriptions of Hermann. 
. Mr. Murchison brought a model of this mass from Nijny Tagilsk, which was presented to him by 
the Directors. 
3 c 
