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

[Göran Axelsson]

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!

/Göran


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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