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Identity HelpGartrellite (?) from Mt. Bonnie mine, Grove Hill, AUS

18th Sep 2017 16:55 UTCJoan Rosell 🌟 Expert

Hi,

I bought an specimen from Mt. Bonnie mine, Grove Hill, Australia

labelled as Mimetite and Conichalcite, but I have analysed differend crystals.

Hexagonal beige prisms show to be mimetite, green crystals duftite,

but very small yellow crystals have shown results similar to gartrellite.

What is your opinion?

Best Regards

Joan Rosell

18th Sep 2017 17:23 UTCReiner Mielke Expert

Seems to be a reasonable assumption however since it is not reported from that locality why not thometzekite?

18th Sep 2017 18:53 UTCGuenter Blass

Hi Joan,

I would also accept Gartrellite.

Maybe a mixed crystal with Yancowinnaite?

18th Sep 2017 21:38 UTCRalph S Bottrill 🌟 Manager

Maybe an Fe-rich Gartrellite or the as-yet unnamed Fe-analogue of Yancowinnaite?

Thometzekite lacks significant Fe, but it needs a full probe analysis and XRD; it could contain S also.

19th Sep 2017 08:46 UTCUwe Kolitsch Manager

Seems to be an Al-bearing gartrellite; pure gartrellites always have Cu:Fe ~ 1:1 and no S; here we have Cu:(Fe,Al) ~ 1:1.

Possible overlap of Pb and S peaks should be checked.

19th Sep 2017 12:16 UTCJoan Rosell 🌟 Expert

Thank you to all for your appreciated opinions and comments.

I will recheck sample to determine if S is present, but Pb peak not show a visible "shoulder" for S... I will analyze some more samples from the same specimen and I will publish here results... XRD complicate, not enough sample.

19th Sep 2017 14:35 UTCJeff Weissman Expert

Both the appearance and composition suggests segnitite (PbFe3+3(AsO4)2(OH,H2O)6), with considerable substitution to philipsbornite (PbAl3(AsO4)2(OH)5 · H2O), copper is a common impurity in this minerals or could be a fine grained inclusion of something else.

19th Sep 2017 16:00 UTCJoan Rosell 🌟 Expert

Thanks a lot Jeff, I will inform about new analysis next weeks...

Salut

Joan

19th Sep 2017 16:05 UTCReiner Mielke Expert

"copper is a common impurity in this minerals" In what form? Are you suggesting it is a mixture and if so what proof have you? Maybe the iron is the impurity? Why not the Pb? The possibilities are endless using your impurity arguement.

19th Sep 2017 16:06 UTCUwe Kolitsch Manager

Jeff: segnitite can be ruled out - it never has Cu>(Fe,Al); the ratio Pb:Fe(+Al,Cu) is different (1:3).

The bright greenish yellow colour also fits gartrellite quite well.

19th Sep 2017 16:44 UTCJoan Rosell 🌟 Expert

Some more analysis... Al is not detected in one of the analysis.

I will perform new analysis next weeks.

Salut

Joan Rosell

19th Sep 2017 23:27 UTCFrank Keutsch Expert

Probably not a problem but watch out for S,K vs Pb,M interference and As,L vs Mg,K interference... I would say both gartrellilte and perhaps thometzekite look reasonable...

Frank

25th Sep 2017 11:14 UTCJoan Rosell 🌟 Expert

-- moved topic --

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