[meteorite-list] Brown Crystals Orange Crystals...was advice needed

From: Göran Axelsson <axelsson_at_meteoritecentral.com>
Date: Sat, 21 Feb 2009 20:33:47 +0100
Message-ID: <49A0571B.6030402_at_acc.umu.se>

To me it doesn't look like titanite. The angles are totally wrong and
the flat sides. (looking at picture #17, Crystal shape 2 reflected light
x40) For me it looks more like a pyroxene crystal.
Anyhow, it's an easy test for a microprobe.

Good luck and thanks for the look!

/G?ran


Mr EMan wrote:
> Hello Jim,
>
> The brown opaque elongated lozenge-shaped crystal(s) which are in cross section in the thin section, very much resembles titanite CaTi[O|SiO4] formerly known as sphene. The cross-section shape is classic for sphene IMO. Sphene is something like 2.5 to 3 times longer on the width axis than on the height axis but this is just memory so please verify that yourself. Mindat.org is a place to do specific mineral searches, BTW.
>
> There is also a complicated Titanium bearing mineral called titanate with an"a":
> CaAl2Si2O8-Fe2TiO4-FeTi2O5 which I assume as some spinel form based on the description at mindat.org. My guess is that this forms upon interaction with Fe-vapor in subsequent metamorphoses by impact melting of the lunar soil??? I am not saying the crystal you have is titanate but just wanted to impress you with my Googling skills. Just kidding! I mentioned it in case you accidentally get sent to that page owing to similar spelling.
>
> Rutile, TiO2 forms blades, needles, and hexagonal prisms--Yet another titanium mineral common in lunar rocks. I caught a slide suggesting a hexagonal "orange structure was possibly a glass sphere" but given the rays within it, that might be rutile.
>
> All these minerals have been found in lunar rocks /meteorites AFAIK.
>
> For what it is worth, have you considered a cosmic ray track count as well? I don't know the cost but you may have enough left over from TS prep to or the TS itself.
>
> Congrats on the research and specimen prep so far: Impressive!
> Elton
>
> --- On Fri, 2/20/09, Suzanne and Jim <suzieandjim at yahoo.com> wrote:
>
>
>> From: Suzanne and Jim <suzieandjim at yahoo.com>
>> Subject: [meteorite-list] need some advice,
>>
>
>
>
>
>> I am trying to determine the nature of the
>> orthorhombic-like opaque red/brown crystals I have seen in a
>> slice I am considering having analyzed.
>>
>
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Received on Sat 21 Feb 2009 02:33:47 PM PST