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 <[email protected]> wrote:
From: Suzanne and Jim <[email protected]>
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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