ORE DEPOSIT THEORIES. 241 
some connection between the two. Unless the axinite was 
deposited at the same time as the pyritic deposits, and from 
identically the same solutions, the only possible connection 
which they can have is that the solutions which deposited 
the pyritic deposits ascended by the same fissures as the 
axinite. If this is the case, these fissures were formed before 
the pyritic deposits, and therefore the latter were at. the 
time of their formation in direct connection with the granite 
hearth. 
These arguments are decisive against the sedimentary 
origin of these deposits, and taken in connection with the 
fact that both stannic and boric emanations are known to 
have taken place from the tourmaline porphyry, asevidenced 
by the presence of tin veins in that rock, and of the tour- 
malinisation of the adjoining country-rock, they form the 
strongest possible presumption in favour of a_ plutonic 
origin. 
The Colebrook Pyritic Copper Deposits. 
These deposits are situated two or three miles east of the 
tin deposits which have just been described. There are here 
no less than six very large pyritic bodies, varying in width 
from 20 to 60 feet. Of these, four have been shown to be 
continuous in strike for from 500 to 700 feet at least. The 
deposits, however, do not consist by any means of solid 
pyrites, though bands of practically solid ore occur up to 
20 feet in thickness. Perhaps the bulk of the lode-matter, 
however, consists of axinite and actinolite, with more or less 
pyrites, and often considerable amounts of copper pyrites 
distributed through it. The great bulk of the ore presents 
a similar banded appearance to that already described as ~ 
occurring at the Cornwall Mine. There can be no doubt of 
the metasomatic character of the deposit. The rock which 
has suffered replacement was in part a’ laminated shale, in 
part limestone, and every gradation between these two rocks 
and the normal lode-matter can be observed. The principal 
minerals present in these deposits, arranged approximately 
in order of their abundance, are the following : —Actinolite, 
axinite, pyrrhotite, iron pyrites, copper pyrites, arseno- 
pyrite, calcite, datolite, danburite, and quartz. 
These deposits differ from the pyritic tin deposits princi- 
pally in the absence of tin, the greater abundance of axinite 
actinolite, and the fact that the latter are more closely 
associated with the pyrites. In the pyritic tin deposits the 
axinite, &c., only occur in veins through the pyritic bodies, 
and here the presumption is that the axinite veins are of 
later age than the latter. At the Colebrook, on the other 
hand, the pyritic deposits were formed simultaneously with 
the deposition of the axinite and the actinolite. At the 
R 
