Hi Pavel,
Being bold beyond measure I'd suggest stilpnomelane. I have seen it
(though much bigger and probe-able) in similar parageneses from Catalina
Island, California. This looks like it is too small to get reliable results
though.
Kind Regards,
Martijn
On Wed, 30 Dec 2009 18:32:35 +0100, Christian Nicollet
<[log in to unmask]> wrote:
> Pavel Pitra a écrit :
>> 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.
> In a section really perpendicular to the cleavage of the mica or the
> cracks in the garnet , the “mineral” probably must be very thin ? I
> agree with Eric.
> It looks like the "inclusions of chiller" in pyroxenes.
> C......
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