V.—GEOLOGY. 
Art. LXXXVI.—An attempt at an explanation of the origin of Mineral Veins, 
particularly those of Gold and Silver. By J. C. Crawrorp, F.G.8. 
[Read before the Wellington Philosophical Society, 29th July, 1876.) 
Numerous theories which have been propounded with regard to the origin of 
mineral veins are generally acknowledged to be by no means satisfactory or 
convincing, and it may be said that the world is in the dark upon this 
subject. 
It is extremely improbable that I shall be able to throw any light upon 
a subject in which so many have failed, but I have got hold of an idea, and 
it may as well be ventilated to see if there is anything in it. 
It may be said that for all practical purposes mineral veins are only 
found in the paleozoic rocks, and chiefly in that range of those rocks called 
‘‘silurian.’’ They may be found in small quantities in newer rocks, but in 
that case they are apt to prove treacherous to the miners. 
Now there must be some good and sufficient reason for the locality of 
minerals being in the paleozoic rocks in question, and if we find out this 
reason we may have solved the difficulty. 
Late researches in deep sea soundings have established this fact, that in 
the deeper parts of the ocean, below the depth of 2,500 fathoms, the water 
is strongly charged with carbonic acid, which is supposed to produce a 
rapid solvent or decomposing effect upon most substances brought within 
its influence. 
It is, I believe, an established fact that silver can always be detected in 
sea water. Now, supposing this silver, in whatever combination it may be, 
to come within the influence of carbonic acid at great depths, might it not 
be, as it were, brought together and condensed by the action of the acid? If 
silver is always present in salt water may not gold be present also, although 
from its greater rarity more difficult to detect, and may it not be precipi- 
tated in the same way in which I have supposed silver may be affected. 
On the other hand, supposing the rocks composing the floor of the ocean 
to be fractured, the fissures may be penetrated with warm water or gases 
from below, containing metals in solution, which coming in contact with the 
carbonic acid may be precipated as carbonates or otherwise; or the waters 
of the ocean entering, the fissures may be the medium by which metals 
