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Identity HelpTellurantimony?

16th Jul 2015 16:23 UTCJyrki Autio Expert

Hello

I thought buying a tellurantimony from Kutemajärvi gold mine, Finland, but noticed the tenacity and color are a problem. Maybe it is another mineral.

Tellurantimony is supposed to brittle. This mineral breaks to small flakes (eg. micas) and these flakes can be folded or bent back and forth few times before they break. I would say it is somewhat malleable.

The color is pale bronze yellow, but it might come from tarnishing.

16th Jul 2015 17:37 UTCJyrki Autio Expert

"Flexible" might be the proper term, not malleable.

16th Jul 2015 18:21 UTCRob Woodside 🌟 Manager

I've never had a big enough Tellurantimony to observe its flexibility. I'd be surprised if it was brittle. If so that would differentiate it from the other several Tetradymite group minerals occurring there. That is at least what you have and to nail the species would require EMPA and SCXRD.

16th Jul 2015 19:18 UTCJyrki Autio Expert

Hello Rob,

I re-checked and didn't find anything about tellurantimony tenacity. It is my mistake and flexibility seems right property on second reading about tetradymite group.

Then only color is what stays odd. It looks like it is very light bronze yellow on fresh surfaces and darker bronze on tarnished surfaces.

Cheers

Jyrki

16th Jul 2015 19:31 UTCRob Woodside 🌟 Manager

Melonite occurs in bronze flexible plates and the color differentiates it. I only see tarnish in your photo.:-(

16th Jul 2015 21:16 UTCPavel Kartashov Manager

My confirmed tellurantimon is very remarkable metallic-black colour. It similar to black shining hematite "mica" (not transparent, without red reflections). Soft, black and shining. In this sence it is very different from other known to me platy tellurides (Bi, Bi-Pb, Bi-Pb-S etc.) which are mostly grey or white.

16th Jul 2015 22:34 UTCRob Woodside 🌟 Manager

The only Tellurantimony I have seen was from an SEM image. For the most part Tellurantimony, like mattagamite is an invisible mineral from Mattagami, not withstanding these photos - http://www.mindat.org/gallery.php?loc=579&min=3904

16th Jul 2015 23:14 UTCPavel Kartashov Manager

I should to photograph my specimen from Armenia.

17th Jul 2015 01:32 UTCBen Grguric Expert

I have seen tellurantimony from the Golden Mile, Kalgoorlie to several mm associated with petzite and gold. It was dark with a pinkish-bronzy tarnish and was lighter grey than petzite and very soft under a needle. It did not form flexible plates that I could see. Perhaps you have molybdenite? You might want to try EDS or take it to someone like Kari Kojonen at the Geol Survey of Finland.

17th Jul 2015 09:00 UTCJyrki Autio Expert

It seems there is some doubt about appearance. I will have an EDS made from it next.

Thanks.

Jyrki

18th Jul 2015 10:35 UTCIlkka Mikkola

Hello Jyrki

Tellurantimony is a very rare mineral at Kutemajärvi. I think that it has been identified only once from Kutemajärvi. It was a small under 50µm grain with tellurobismutite.

Ilkka

18th Jul 2015 15:37 UTCFrank Keutsch Expert

I will add here what I already wrote in a PM.

Tellurantimony forms flexible, soft, aggregates with perfect cleavage in "plates". The larger pieces I have seen (one exceptional one with plates to about 2 inches) show a light grey color that may get a little dull on exposed surfaces.

This photograph (Tellurantimony) shows the stacked nature of plates a little bit.

However, I don't think it is distinguishable from more common tellurobismutite etc. without analysis, but EDS works well.

That being said, macroscopic tellurantimony is quite rare in my admittedly limited experience. Many pieces of supposed tellurantimony I have studied, also from Mattagami, Japna etc., turned out to have no tellurantimony that I could find.

Frank

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