[meteorite-list] Dhofar 019 organettes- search for the invisible.

From: Matt Morgan <mmorgan_at_meteoritecentral.com>
Date: Thu Apr 22 10:31:24 2004
Message-ID: <403520E9.1070200_at_mhmeteorites.com>

Howard:
It was my undertsanding that these were only observed in thin section,
or using and SEM, in rare cases. You can see some of the caliche
(CaCO3) veins (terrestrial) in some of the large slices.

Here is a good summary paper of Dhofar 019
<http://www-curator.jsc.nasa.gov/curator/antmet/mmc/XVII-%20Dhofar.PDF>

This is a really nice and "cheap" martian meteorite. Several dealers on
this list have some.

Matt Morgan

Howard Wu wrote:

> I wish to thank the those who took time to look for orangettes in there
> large slices of Dhofar 019 and for whatever reason posted me privately.
> (Perhaps you don't wish to let others know what big slices you have.)
>
> For my part, my parttslice was only 0.19gm and I saw nothing (up to
> x60.) After doing further reading, I understand indiviulal organettes
> would be in the nanometter range. But I still hoped that collectively
> that an area of orangettes might be visible. Calcite veining at least
> should have been apparent on some larger slices.
>
> Two observers didn't see the anything that may have been organette
> related. Observation to 120x. However, one person did make the following
> observations:
>
> " I looked under my scope for the orangettes and can see several areas
> where tiny alteration specks are present. Look like they are 0.5 mm or
> less in size. Some are located along fractures (one at an intersection)
> but they don't seem common. Another fracture intersection has no
> evidence of any alteration. Other alteration areas are present but don't
> seem associated with fractures. A large areas one to two cm in diameter
> seems to have no evidence of anything that might be an orangette. In
> fact, most of the slice appears very fresh. However, in another
> portion, orangish alteration products appear to be fairly common."
>
> Comments, anyone?
>
> Interesting excercise in amateur scientific verification. I will follow
> up to any other contributions to this search among us
> collectors. (Unless you wish to post directly to the list.) And next
> time I get to Mono Lake I see what I can be seen on those tufas.
>
>
> Howard Wu
> Bishop, CA
>
>
>
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Received on Thu 19 Feb 2004 03:47:37 PM PST