Strange rock? Need help to identity It

Hi guys a friend of mine found this recently it’s heavier than lead and is non magnetic hard as you can’t file it. it rings up 62 63 on an ptpro anyone got a clue to what it might be.

Where was it found - Coromandel say near Tui Mine or near where mining was carried out? It could be Galena which is a principal ore of lead.

It was found in Dunedin but could have come from anywhere!

If it was found in Dunedin then it wont have come from here. Someone must have dropped it or lost it I guess. There is one rock similar in Appearance found in the wider Dunedin District and that is Antimony Ore - found at Waipori, Pukerangi and near Alexandra. It is also quite heavy.

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Very interesting I will look into it thanks very much

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Crystal structure suggests antimony.

Just had a look at antimony and it says it is a softer rock this thing is hard

Yes, in theory if its either Galena or Antimony you should be able to scratch it with a steel nail. Are you able to scratch it with porcelain or glass?

“pure” antimony is soft. Check your messages.

Could be Galena. Yes antimony is soft but in saying that how hard is soft or how do we interprete ‘soft’? I have antimony here and dont really consider it soft in the way in which l interpreted the word soft. I see talc as soft and think that antimony is harder than talc. My guess is however Galena. The more I look at it the more I think it IS Galena BUT without holding it and seeing it then it is hard to make a definitive identification.

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Got another photo

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Looks like a piece of quality west coast coal to me , throw it in the fire see if it burns :slight_smile:


Still looks like Galena to me. This photo shows a corner of a 25kg block of Galena from the Tui Mine on the Coromandel. The bottom right looks quite similar to yours.

I do note the different colour though but put that down to camera and light. Galena is gray and my photograph shows its exact colour.

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That second pic looks Galena, more of the cubic structure coming through. The first looked quite tabular.

The hardness would seem to rule out Galena.

Have you tried a scratch test, streak test? Hit it with a hammer & see if it shatters or flattens a bit. :laughing:

JW :cowboy_hat_face:

The Galena in my photo is not as soft as the word ‘soft’ infers. Not platinum if the structure is anything to go by.
Hint - take it to the Geology Departmemt at the Otago University and then enlighten all of us as we can only offer you informed guesses without seeing and handling it.

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Going out on a limb here. Extreme hardness and density would seem to suggest it might be a piece of a carbide tooling, used for industrial cutting tools, perhaps a tooth from a piece of mining equipment that has got mutilated after breaking off.
If so it would be most likely to be tungsten carbide powder in a cobalt matrix. If this is what it is, the test to identify it would be that carbide tooling will be magnetic.

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Guess we’ll never know.
(I’ll change my answer and say it’s Pt and he’s skipped the country :smile:)