Pavel,
I would say Fe oxides, Fe hydroxides, Fe oxyhydroxides are
likely. You may have more than one phase.
cheers,
eric
On Dec 30, 2009, at 11:55 AM, Pavel Pitra wrote:
> Hello,
>
> studying glaucophane + cpx + grt-bearing rocks from Syros (Greece)
> and Ile de Groix (France), I recently came across a tiny but
> outstanding mineral that I am ashamed to admit not to be able to
> identify. It occurs in several samples from both localities, but I
> never saw it so clearly in other rock types (at least I don't
> remember). I'm attaching three photographs of it and would be very
> grateful for a suggestion.
>
> It is brownish-red to orange, slightly pleochroic with relatively
> high relief and occurs typically as very thin lamellae (inclusions?)
> in white micas, apparently parallel to the cleavage. Locally it also
> ocurs in garnet. It is so thin that the optical properties interfere
> strongly with the mineral hosts. I'm afraid that for the same reason
> microprobe analyses wouldn't be conclusive either. Normally I would
> neglect it as a "iron hydroxyde", but its attractive appearance in
> these sections (and the fact that it seems enjoy such mineral
> assemblages) prevents me from doing so.
>
> Thanks a lot for any suggestions!
>
> Have a nice end of the year, and a good new one!
>
> Cheers,
>
> Pavel
>
> --
> Pavel PITRA
> Geosciences Rennes email: [log in to unmask]
> Université Rennes 1 tel: (++33) 2.23.23.65.06
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