[meteorite-list] Gebel Kamil webpage

From: info at niger-meteorite-recon.de <info_at_meteoritecentral.com>
Date: Thu, 29 Jul 2010 16:56:07 +0200 (CEST)
Message-ID: <517995254.270530.1280415367862.JavaMail.open-xchange_at_oxltgw02.schlund.de>

?
I happily acknowledge your experience Jason, but that is not the point. I can
only speak for myself, and I?do not base such statement on a photo without any
chance to study the evidence in situ.?
?
By the way, the original source of both pictures you quote is the Museo
Nazionale Antartide, although the source you quote does not give credits and has
obviously changed the aspect ratio of the second photo to make it fit the
website template.
?
In the supplement to the Science-express article of Folco et al. on the Kamil
crater, the left photo has the original caption:

"An 83 kg meteorite specimen found 230 m due north of the crater showing
regmaglypts"
?
The photo on the right, which is?from the Museo Nazionale
Antartide Kamil crater website, has the original caption:

"largest recoveredmass ca. 80 kg".
?
Luigo Folco from the Museo Nazionale, the head of the Kamil expedition, wrote in
the express version of his article in Science, that the finds of his team
consisted of shrapnel "except one individual fragment of 83 kg?.?I see no reason
to doubt his words.

Regards,
Svend



Jason Utas <meteoritekid at gmail.com> hat am 29. Juli 2010 um 15:42 geschrieben:

> Hello Svend, All,
>
> I probably have as much experience as you do with desert irons; I
> agree, but look at the photos.? The first shows an xxkg half-buried
> individual (the 83 kg?) that clearly protrudes more than 5cm above the
> ground.? Furthermore, you can tell very clearly that it is
> well-embedded in the ground.
>
> The second photo shows a meteorite that exhibits obviously different
> features.? But both irons are "right-side-up."
>
> Compare to other Gebel Kamil irons that have been found.? They all
> show painfully clear differences in colour and texture:
>
>
> http://shop.ebay.com/?_from=R40&_trksid=p3984.m570.l1313&_nkw=gebel&_sacat=See-All-Categories
>
>
> - Or are you telling me that you can't tell which side was facing down
> in all of those photos?
>
> ...And both are sitting in undisturbed soil.? It takes one hell of a
> strong guy to pick an 83 kg iron up and toss/drop it so that it lands
> without disturbing the dirt around it.? In fact, if you look at the
> soil in each photo, it is *completely* undisturbed.? Neither one of
> those irons was moved before the photos were taken.
>
> Regards,
> Jason
>
>
>
> On Thu, Jul 29, 2010 at 6:26 AM, info at niger-meteorite-recon.de
> <info at niger-meteorite-recon.de> wrote:
> >
> > The effects of sand abrasion (corrasion) and chemical weathering (corrosion)
> > of
> > objects on a desert surface, apart from other factors, depend considerably
> > on
> > the texture and composition of the original surface, but also on the
> > dimensions
> > and the depth to which an object is buried in the soil.
> >
> > It does make a difference whether the surface to be attacked is coated by a
> > smooth layer of magnetite and other iron oxides (fusion crust), or whether
> > the
> > surface is a shear surface without any protective coating (and with?large
> > micro
> > surfaces inviting contaminants to adhere).
> >
> > Also the forming of caliche or calcrete due to evaporation and condensation
> > processes in hyper arid regions is usually limited to a very narrow zone
> > close
> > to the surface. Parts of objects buried beyond this zone or protruding above
> > it,
> > are affected in a much lesser degree. This effect can be observed quite well
> > on
> > Kamil shrapnel. These conditions allow to interpret caliche deposits on
> > desert
> > meteorites in certain cases as markers, indicating previous ground levels of
> > deflation zones. The strongest activity of chemical weathering in hyper arid
> > environments is limited to this very zone as well.
> >
> > If we look at the majority of the corrasion activity, which is one of the
> > factors responsible for the characteristic sub-milimeter pitting on the
> > Kamil-shrapnel, it is limited to a specific zone as well. At normal
> > prevailing
> > wind velocities the leaping motion of quartz sand grains (called saltation),
> > which abrades the surface of an obstacle, is usually limited to 0 ? 5
> > centimeters above the ground. But most of the damage occurs in the lower
> > region
> > of the saltation zone.
> >
> >
> > Thus, conclusions drawn from weathering patterns of iron objects of
> > different
> > sizes, surface qualities?and burying levels should be considered with
> > caution.
> >
> >
> > Regards,
> > Svend
> >
> >
> > Jason Utas <meteoritekid at gmail.com> wrote at 29. July 2010, 13:31:
> >
> >> I had this post as a draft earlier - seems a perfect time to post it:
> >>
> >> Hello All,
> >> The initial expedition did in fact find more than one *complete
> >> individual* from the fall.
> >> If you take a look at the following website, you'll see links to two
> >> photos:
> >>
> >> http://www.b14643.de/Sahara/Kamil_Patatrac_Crater/index.htm
> >>
> >> Photo links:
> >>
> >> http://www.b14643.de/Sahara/Kamil_Patatrac_Crater/Kamil_1big.jpg
> >>
> >> http://www.b14643.de/Sahara/Kamil_Patatrac_Crater/Kamil_3big.jpg
> >>
> >> Take a look at the first and second photos.? Those are both in-situ
> >> photos; the meteorites have yet to be moved, or the dirt around them
> >> disturbed.
> >> Also note the differing shapes and the surface patina of each iron.? I
> >> initially thought that the iron might simply have been rolled over -
> >> but take a look at the patina visible in each photo.
> >> The surface of Gebel Kamil irons varies greatly: especially the
> >> contrast between exhumed and buried surfaces.? Exposed surfaces
> >> typically exhibit a dark patina and sometimes corrosion pitting.
> >> Buried surfaces are often better-preserved, but look entirely
> >> different; they're rusty.
> >>
> >> Both of the photos above are of the upper, sandblasted surfaces of
> >> meteorites that have yet to be moved from where they were found.
> >>
> >> So, two or more individuals.
> >>
> >> Regards,
> >> Jason
> >>
> >>
> >> On Thu, Jul 29, 2010 at 3:59 AM,? <bernd.pauli at paulinet.de> wrote:
> >> > http://www.b14643.de/Sahara/Kamil_Patatrac_Crater/index.htm
> >> >
> >> > Gary wrote: "...some of (what I believe are) Mirko's slices..."
> >> >
> >> >
> >> > Yep, and the 17.5-gram endcut pictured on the right
> >> > now resides in the Bernd Pauli meteorite collection :-)
> >> >
> >> > Note that "cometary" inclusion of schreibersite rimmed
> >> > by swathing kamacite and displaying shear deformation.
> >> >
> >> >
> >> > Best regards,
> >> >
> >> > Bernd
> >> >
> >> >
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Received on Thu 29 Jul 2010 10:56:07 AM PDT