[meteorite-list] What does fresh Sikhote Alin fusion crust look like?

From: Rob Lenssen <rlenssen_at_meteoritecentral.com>
Date: Sun, 14 Jan 2007 17:35:13 +0100
Message-ID: <008a01c737f9$f76bf3e0$9600000a_at_EIGENAARNJEQJY>

Dear List,

Inspired by resent discussions about fusion crust on iron meteorites, I'd
like to share some information (and thoughts), I collected since I bought my
first Sikhote Alin in 1993. (I hope this will not evolve in discussions
about how to call something.) Ever since I bought my first "crusted" Sikhote
Alin, I have been wondering what it would have looked like, when it fell in
February 1947, into the snow of the Russian Taiga.

>From Krinov's book "Giant meteorites" (English edition 1966), Krinov's
article "Neue Untersuchungen des Niedergangs und Sammlung von Teilen des
Eisenmeteoritenregens von Sichote-Alin" (Chemie de Erde; 1970) and Buchwald's
"Handbook of Iron Meteorites" (1975) I learned the following:

>From 1947 until 1950 four Russian Academy of Sciences expeditions explored
this meteorite fall. Only in the first of these expeditions, crusted
individuals were found (several months after the fall). Krinov mentions that
these individual were collected from the forest surface soil, and were
"completely or almost completely free of soil pollution and rust". Krinov
described the color of the crust as "grey colored with blue-ish tinge" and
"ash grey".

After an intermission of 17 years, in 1967 the expeditions were resumed.
Also 1968 and 1969 had expeditions. Krinov writes of a planned expedition
for 1970. Don't know if this last one actually took place, and if there were
more in the following years. Many more fusion crusted individuals were found
during these 1967 and later expeditions. Krinov writes: "the collected whole
individuals have - during their twenty year stay in the soil - been covered
by a thin oxidation layer and are colored brownish" and "yet many have areas
that have not been covered by oxidation and kept their original dark grey
color". (I translated this from German in English. My native language is
Dutch. Sorry for the grammar...)

When I bought a nice fusion crusted individual (
http://home.planet.nl/~rlenssen/50procent/Sikhote%20Alin-5.jpg ) from Walter
Zeitschel in 1995, he kindly wrote me about it's history. Walter knew Prof.
Krinov personally, and wrote me this specimen originated from a cellar in a
building belonging to a Moscow university. It was found during one of the
later (1967 and later) expeditions and stored in the cellar for tens of
years. At first the individuals were registered and numbered, but when they
became too many, they were just stored in the cellar, where they were found
after 1991. Russian and American dealers bought the specimens and took them
to "the west". The specimen didn't look as in the picture when he got hold
of it. It was still covered with soil. The piece was carefully cleaned by
the use of a little (electrical) steel brush. I expect following link must
also show typical individuals from the later expeditions (please correct me
when I am wrong): http://home.planet.nl/~rlenssen/SA1.jpg . Don't know
anymore where I found this picture, so sorry for not mentioning the source.

There are many qualities of "fusion crusted" individuals going around
nowadays. I think the ones in the previous paragraph belong to the better
quality available. There are also tumbled or heavily wire brushed (resently
found?) specimens like this one:
http://home.planet.nl/~rlenssen/50procent/Sikhote%20Alin-6.jpg .
And then there is my best one: http://home.planet.nl/~rlenssen/SA.htm . I
learned this one was bought in Moscow by an American collector, and that it
originated from the Russian Academy of Sciences. It really differs from the
one I got from Walter. It is lighter grey and doesn't look "sanded". I don't
think it has been wire brushed. Could it be from the earlier expeditions? Or
many a better one from the sixties-expeditions? I'm afraid I will never know
:-(

What I would like to see though, and maybe someone can help me here, is a
good quality color photograph of one of the original (1947) found fusion
crusted specimens. Has anybody on this List been to the Fersman
Mineralogical Museum in Moscow where they are stored? Are there pictures
available? Would appreciate it very much if I could see one.

This epistle has become longer than I planned..., but I hope you will
appreciate the information and maybe help me in my search for an answer to
the question: "What does fresh Sikhote Alin crust look like?"

Kind regards,
Rob Lenssen
 
Received on Sun 14 Jan 2007 11:35:13 AM PST