[meteorite-list] Fusion Crust on Irons - Krinov quoted

From: Rob Lenssen <rlenssen_at_meteoritecentral.com>
Date: Thu, 19 Nov 2009 21:35:50 +0100
Message-ID: <6938324E55014D7D8EBEBB38E706073E_at_EIGENAARNJEQJY>

Let's see what Russian Scientist, and 1947 Sikhote Alin expedition member,
Dr. Krinov wrote about SA's crust:

>From Krinov's book "Giant meteorites" (English edition 1966) page 346:
"The collection of small specimens lying strewn on the surface of the
ground, mainly in the rear part of the distribution ellipse, was carried out
during the First expedition of 1947, immediately after the snow had melted.
The meteorites picked up under these conditions had preserved the most
varied, extremely delicate patterns on the fusion crust (Fig. 238, 239). On
many small specimens picked up from the surface of the ground covered with
old leaves, dry grass, etc., quite well-marked bluish violet tints were
preserved in the ash-grey fusion crust. The meteorites stood out sharply
against the yellowish-brown background of the forest carpet because of their
colour and even the very small ones, a few centimeters across or less (Fig.
193), were easily visible from a distance of several yards."
(Note: The first expedition arrived two and a half months after the fall.)

>From Krinov's article "Neue Untersuchungen des Niedergangs und Sammlung von
Teilen des Eisenmeteoritenregens von Sichote-Alin" (Chemie de Erde; 1970)
page 250, reporting about the 1967 and later expeditions. (Note: I
translated this from German):
"During their twenty year stay in the soil, the collected whole individuals
have been covered by a thin oxidation layer and are colored brownish. Yet
many have areas that have not been covered by oxidation and have kept their
original dark grey color of the fusion crust."
I think this was ment here:
http://home.planet.nl/~rlenssen/SA_216g/216g_Sikhote_Alin.html

All the best,
Rob Lenssen


----- Original Message -----
From: "Martin Altmann" <altmann at meteorite-martin.de>
To: <Meteorite-list at meteoritecentral.com>
Sent: Thursday, November 19, 2009 1:21 PM
Subject: Re: [meteorite-list] Fusion Crust on Irons--Not


Unlike in politics and public opinion (and sometimes in science),
in meteoritics
it sometimes can be more difficult to adhere to theories/legends,
if one gets samples in ones very hands, which exhibit the opposite of that,
the theory postulates.

If you ever had an early picked Sikhote at hand,
or if you had taken from Andi Gren's Boguslavka slices
(a fall, who simply hadn't enough time in field, to develop a magnetite,
wuestite, limonite or whatever -ite weathering crust),
you would be very surprised.

Cause they don't display that ominous blue-ish flimsy luster, which is often
reported as fusion crust,

but a thick and fat layer of a discernibly different matter than the
material beneath, of a dark colour and rough to silky surface.

I never believed in iron fusion crusts neither, but when I got in these
freshly picked up observed falls, I was disabused.

Main problem in that question is, as it was correctly mentioned here,
that we simply have so few pristine samples of fresh iron falls and that
most irons we get in our collections arrive with weathered or artificially
cleaned surfaces.

Now you may argue about the word "crust" as a (pseudo-)scientific term...
well for me scientific terms are best, when they keep most of their meaning
they have in their common use in the language.
And there crust - meanst for me a layer on the outside of an object.

.....and we have the problem, that there exist these freshly fallen lumps
with that strange crust. Shall we hide them in the deepest corner of our
drawers, cause they don't fit in the axiom, that fusion crusts are fusion
crusts only, when silicates are melting?

Sometimes, if the results don't fit into a theory, one has to think about
modifying the theory,

Else there wouldn't be no meteorites in our sense at all,
Nada, Niente, Nix, Nimic,
cause we all would know that they are products of our Aristotelian
atmosphere, solified accumulations of terrestrial vapours and probably
created by lightning strokes,
wouldn't we?

Best!
Martin








-----Urspr?ngliche Nachricht-----
Von: meteorite-list-bounces at meteoritecentral.com
[mailto:meteorite-list-bounces at meteoritecentral.com] Im Auftrag von MEM
Gesendet: Donnerstag, 19. November 2009 04:31
An: Meteorites USA; metlist
Betreff: Re: [meteorite-list] Fusion Crust on Irons--Not

Stopping in a few minutes to state again that all this discussion about
fusion crust on irons is right next to unicorns postulations. Everyone says
that fusion crust on irons exists but no one can come up with the proof.
Non-silicate bearing irons DO NOT/CANNOT have FUSION crust: they have a very
fragile magentite micro-crystal "film" and they have an ablation surface
but, they can't by definition have a "fusion crust" and no matter whom the
expert quoted they still do not have a fusion crust. A fusion crust has to
have a silicate source to for the glass component of the crust-- Nada, Nix,
No How.

Both silicate and non-silicate meteorites have an ablated/ablation surface,
and they can show flight features--but not all meteorites have a fusion
crust. I have some OCs which have flow lines UNDER the fusion crust
remnants.

If anyone still defends the presence of fusion crust on (non-silicate
bearing) irons then show me the "crust"...can't?..ok show me the glass? ....
right then-- no photos, no thin sections, no micro graphs???......And while
there was one close up of an ablated surface showing soft wavy lines of
briefly melted metal that was aligned to aerodynamic vectors--This does not
fusion crust make.

Unlike in politics and public opinion, in science, no matter how often an
untruth is repeated it doesn't become "truth" by majority belief. But
science, being a human endeavor, sometimes can find itself "off track" and
when it does it accepts the error and gets back on track.

Elton
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Received on Thu 19 Nov 2009 03:35:50 PM PST