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Identity HelpAutunite?

4th Aug 2010 14:24 UTCDan Fountain

I was collecting at the Outback quarry in Maine when my friend noticed that some of the conglomerations of schorl were somewhat radioactive. We collected a few pieces of the "hotter" material. When I got home, I checked my specimen under UV, and found it to be speckled with something that fluoresced yellow-green under both LW & SW. Under the microscope, I saw a lot of undistinguished crusts, but also a few areas that had groups of square, platey, transparent yellowish-green crystals. A look through the Mindat autunite gallery showed numerous photos identical to what I was seeing. Here's a crummy photo of what I saw - FOV is about 0.5 mm.

How might I confirm that this is indeed autunite - or what else might it be? My ID was not deemed sufficient grounds to add autunite to the Outback quarry locality mineral list.

Thanks for any assistancet you might be able to offer.

-Dan

4th Aug 2010 14:45 UTCJolyon Ralph Founder

Although your identification is probably correct, there are other minerals - in particular other minerals of the autunite group, which could be mistaken for it. What I don't know, and I'm sure someone will be able to help here, is whether the UV response you have got is enough to categorically confirm it as Autunite (you didn't mention in your other post that you had checked it with UV).

If that is the case, then it's fine to add this information as confirmation of your identity. If not, it might be better to add the 'Autunite Group' instead to the list (http://www.mindat.org/min-29274.html)

Thanks!

Jolyon

4th Aug 2010 15:08 UTCLefteris Rantos Expert

As Jolyon said, Autunite-group members can be indistinguishable.. Fluorescence is a good clue for Autunite (which is indeed brightly fluorescent under both LW and SW UV), but e.g. Uranocircite is also strongly fluorescent and visually identical.

Although Autunite (or Meta-autunite) is by far the commonest species in the group and the most likely candidate for your sample, it would be safer to label it "Autunite group" until you can get a positive ID for it with analytical methods.

Lefteris.

4th Aug 2010 15:35 UTCDan Fountain

Jolyon, Lefteris,

Thank you for your assistance. I'll change it to "Autunite Group", and hope that I can find enough material to have it analyzed.

-Dan

4th Aug 2010 16:37 UTCLuiz Alberto Dias Menezes, Fo.

I have been finding saleeite more frequently than autunite on the specimens I have been collecting on the pegmatites of Northeast Minas Gerais, Brazil; a small single crystal is sufficient to get a qualitative analysis via SEM, and just a qualitative analysis has shown to be enough, I have not seen solid solutions between autunite and saleeite or other autunite-group minerals on those Brazilian pegmatites.

Luiz

5th Aug 2010 15:20 UTCMark Willoughby Expert

Saleeite would have also been my other guess, I know when we first found fluorescing flakes at Toms Quarry, Kapunda, Sth. Aust. we all thought it was autunite until it was tested. The colour of both under UV is almost identical, so I wouldn't rely on that for an id in this case.

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