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Volume 19, 1886


Art. LXI.—On the Occurrence of Bismuth at the Owen, N.Z.

[Read before the Wellington Philosophical Society, 18th February, 1887.]

On the 23rd December last (1886), four specimens of auriferous quartz, as collected from four claims at the Owen diggings by Dr. Hector, were submitted to me for a quantitative analysis for gold.

One of these specimens (No. 1), when treated with mercury for gold, yielded an amalgam which, rather early in the process of sublimation, darkened feebly upon its surface, and towards the end of the process slightly decrepitated.

These phenomena showed, of course, that the mercury used had gathered a minute quantity of some base metal from the quartz operated on.

This metal I found to be bismuth; but the whole of my operations were upon so small a scale, (being limited as they were by the size of the specimen itself), that I could get no quantitative determination of it—having barely enough, indeed, of the metal to get those various reactions of this metal necessary to establish its presence.

As yet I am unable to annourice whether the bismuth exists in a separate state in this quartz, or as an alloy with its gold; but this I hope to be able to determine at an early date, upon receipt of further specimens from the claim where this was obtained. In the meantime, I may remark that I could not observe any metallic bismuth in the rock, nor, after panning it off, did I find any metal but the gold.

Bismuth as a constituent of native gold is stated for in gold from Australia analysed by Northcote.*

Last Sample for Bismuth from the Owen District.

Sir,—Having separated the gold from this sample by simply panning off, without the use of mercury, I was able to get sufficient gold to test for bismuth, when I was unable to find a trace of this metal in the gold. But bismuth was present in

[Footnote] * Dana, p. 5.

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the quartz, though quite undetectable to the eye. The bismuth present is, therefore, certainly native—occurring quite independent of the gold, only accidentally associated with it. Bismuth being a very brittle metal, would be crushed beyond all recognition in the pounding or stamping of the quartz; so would escape detection visually, except in the quartz uncrushed. The quantity of bismuth present in either of these samples is very minute, and of no economic account.—W.S.—To Dr. Hector.”