[meteorite-list] LOVINA REVISITED

From: Darryl Pitt <darryl_at_meteoritecentral.com>
Date: Wed, 9 Dec 2009 03:15:49 -0500
Message-ID: <0B95F6D1-9CC8-4C67-A877-3082AA835FE6_at_dof3.com>

Well, I had an interesting day today....

This morning I met with Roy Clarke, Linda Welzenbach, Cari Corrigan,
Glen MacPherson, and Tim McCoy at the Smithsonian. During our get-
together Tim made several observations as to why Lovina could very
well not be what it has been made out to be---which is to say, a
meteorite---and why more work must be done.

In Tim's words....

1) The sulfides are not simply troilite and appear optically to be
multiple phases, including one that looks like the Ni-rich sulfide
pentlandite.

2) Although the presence of the octahedrons has been attributed to
weathering, the structure of the remainder of the meteorite shows fine
stringers of sulfide, not large areas that would easily weather out
leaving such octahedron.

3) On one polished slice, the sulfides clearly wrap around one of the
indentations, rather than the cross-cutting relationship one might
expect from a significantly weathered iron meteorite.

4) The composition given - high Ni coupled with moderately high Ga
and Ge - is difficult to reconcile with a meteorite composition.
Iron meteorites acquire high Ni concentrations through 1 of 3
mechanisms. Oxidation simply changes iron to FeO, leaving Ni behind.
This can produce high-Ni irons with modest Ga and Ge. Nebular
condensation can also produce high-Ni iron which then melts to form
cores in which high-Ni iron meteorites form. This process, however,
occurs at high temperature where the volatile elements Ga and Ge are
depleted. Finally, you can produce high Ni through fractional
crystallization. Ni prefers the solid phase when a core crystallizes,
so early irons are low in Ni and later crystallizing ones are high in
Ni. However, Ga and Ge behave opposite of Ni, so low Ni irons are
high in Ga and Ge and high Ni irons are low and Ga and Ge. The
published Ga and Ge values are at least a factor of 15 higher than
reported for similar iron meteorites.

5) The holes exposed in the center of the specimen are not the shape
one would expect of weathering, but seem circular. Circular vugs are
commonly produced in slags when gases try to escape.

There was more...including the fact that Indonesia is a nickel-rich
locality as well as Tim's conclusion that Lovina was most likely a
highly weathered example of a smelted Ni-rich sulfide.

Sales have been suspended and monies are in the process of being
returned. Further testing will be done to confirm Lovina's place of
origin and the results will be posted to the list by mid-January.

I think I'll go see the new Clooney film "Up In The Air." Ohhh---and
might anyone want an inexpensive 13 kg specimen of Willamette for
Christmas?!


And how was your day? ;-)
Received on Wed 09 Dec 2009 03:15:49 AM PST