[meteorite-list] Gebel Kamil webpage

From: Jason Utas <meteoritekid_at_meteoritecentral.com>
Date: Thu, 29 Jul 2010 06:42:42 -0700
Message-ID: <AANLkTimbbfk2s+2Xf2fRy4H9b_Jexp9emBiYkrVwiP-o_at_mail.gmail.com>

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 09:42:42 AM PDT