![Thumbnail: [Volume 10, 1877 page 448]](/journals/rsnz/images/rsnz_10/thumbnails/rsnz_10_00_0511_0448_ac_02.gif)
Art. LXVI.—On the Result of an Examination of certain of our Manganese Ores for Cobalt.
[Read before the Wellington Philosophical Society, 12th January, 1878.]
In June last I had to estimate the proportion in which cobalt existed in a variety of manganese ore from New Caledonia, known as asbolite. This one, though physically differing in no respect from several of our manganese ores, afforded me no less than 7.2 per cent of cobalt, a proportion which gives the mineral a considerable market value, cobalt being a comparatively rare metal, and one which is now in much request.
In consideration of this, therefore, I deemed it highly necessary that an especial examination should be made for small quantities of this metal in those of our manganese ores which compare most closely with this from New Caledonia, for it appeared to me as not at all improbable that a little cobalt might have escaped detection by analytical processes, the purpose of which had been merely to determine the fundamental character of the ore, and in such a case an opportunity might have been lost for guiding mining opera-
![Thumbnail: [Volume 10, 1877 page 449]](/journals/rsnz/images/rsnz_10/thumbnails/rsnz_10_00_0512_0449_ac_02.gif)
tions to the working of any payable cobaltic vein which such feebly cobaltic ore may indicate. I accordingly tested a number of our ores most likely for cobalt very rigorously, but I am sorry to have to inform you that the results obtained were in every case entirely negative. I do not mean to be understood by this as affirming the non-existence of cobalt in all these cases, but only that I could not find it by any ordinary course of analysis, and in consequence if it is present it can only be so in quantity so minute as to be of no indicatory value when found.
But although such is the character of my results I make no apology for bringing them under your notice, as I am under the impression that you will think it a serviceable act to make public in this way the fact that certain of our ores—greatly resembling the cobaltic ore, asbolite—are not cobaltic, and do not indicate the existence of such an ore in the neighbourhood they are in.
Those I have tested are from Wellington, Nelson, Marlborough, and Auckland.
All these are essentially hydrous oxides of manganese with varying proportions of iron oxide.
It will be very interesting for us to know the matrix of the New Caledonian ore and the geological character of the formation in which it occurs. I observe that the ore contains a little chromate of iron (crystalline), a fact which would seem to indicate that it occurs in some serpentine rock.