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ANKERITE VEINS OF LONDONDERRY—LOUIS. De 
ing when heated, its distinct red colour and streak separate it 
from all the other hydrates of Iron; and numerous and indefinite 
though they are, there is no species with which it can fairly be 
classed. 
As regards the origin and formation of the Londonderry de- 
posits, the following appears to be their history, as far as our 
present limited Geological knowledge of this region allows us to 
read it. The close of the Silurian epoch was brought about in 
this region by the elevation of the land now forming the Cobe- 
quid Mountains. This elevation was accompanied by extensive 
dislocation and fracture of the strata, and in this way a long 
series of clefts was produced in the region extending along the 
base of the Cobequids, this having evidently been the line of 
least resistance to fracture. These fissures were then filled with, 
Ankerite and Sideroplesite, introduced, as I believe, in solution, 
in water. It has been supposed by some. that these minerals 
were introduced into the fissures in a state of fusion, or at any 
rate, under conditions of intense heat. I am not aware that the 
feasibility of fusing either of these minerals without decomposi- 
tion has ever yet been demonstrated, but as Caleie Carbonate 
has been fused under pressure, it is possible thata similar result 
might be obtained with them. If then the plutonic hypothesis 
is the correct one, their formation must have been effected at a 
sufficient depth in the interior of the earth to produce the neces- 
sary pressure as well as heat ; but it is by no.means clear to me 
how, at so great a depth, where-the surrounding strata must at 
least have been softened, such sharp,and extensive fissures could 
have been produced. Moreover, the efféct of this intense heat 
ought to be traceable in the: walls of the veins. Some. of the 
walls of the very narrow veins certainly consist of highly meta- 
morphic slate, but I found that a sample taken. from the: walls 
of the large Ankerite veim at Acadia Mines was. highly plastic 
when ground fine and mixed with water, and that it contained 
as much as 8.15 p.c. of combined water. These walls had surely 
not been exposed to.a temperature above red heat, unless indeed 
rehydration in such a case were possible. Fragments of the 
walls with sharp edges, and apparently differing in. no respect. 
