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Date: 25 Aug 2006 15:04:17
From: radiantbluelight
Subject: Sikhote-Alin meteorite mid-air impact craters? (pictures in links)
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I have a 40 gram oriented individual with two interesting impact
"pits". It looks like something struck this meteorite in mid-air.
Possibly shrapnel from the 5.6 km explosion during its descent. I
found it a recent gem/mineral show and paid considerably less than it's
worth.
I want to know if it's common to see these type of scars on other
Sikhote-Alin specimens.
I believe at least one of the two rips is from being hit by
smaller pieces while in mid-fall. I have examined the edges of the
rips under magnification and see that they are rounded off by heat. It
doesn't feel sharp on the edges as you would expect on a ground impact
with rocks. In fact, there are odd looking molten globs inside the
rip.
Pic1: This is a close-up of one of the rips. Notice the long scar
running along the leftmost side of this pit. Notice the molten
material on far right of rip. How much force would this take? It just
looks like something tore into this so hard that it liquified from the
force.
http://img89.imageshack.us/img89/2028/meteoritepic1kp7.jpg
Pic2: This shows how flat the top left edge is. Definitely oriented
with big roll over lip.
http://img155.imageshack.us/img155/2021/meteoritepic2ew9.jpg
Pic3: Top down view of all the thumb prints
http://img162.imageshack.us/img162/8509/meteoritepic6zi2.jpg
Pic4: Second possible rip is the indentation near bottom right. There
is molten material inside this rip, as well.
http://img178.imageshack.us/img178/6162/meteoritepic7ma0.jpg
Wiki quote:
"As the meteorite entered the atmosphere, traveling at a speed of about
14 km/s, it began to break apart, and the fragments fell together. At
an altitude of about 5.6 km, the largest mass apparently broke up in a
violent explosion.
The strewn field for this meteorite covered an elliptical area of about
1.3 km2. Some of the fragments made craters, the largest of which was
about 26 m across and 6 m deep. Fragments of the meteorite were also
driven into the surrounding trees."
RBL
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Date: 25 Aug 2006 22:29:39
From: Chris L Peterson
Subject: Re: Sikhote-Alin meteorite mid-air impact craters? (pictures in links)
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On 25 Aug 2006 15:04:17 -0700, "radiantbluelight"
<radiantbluelight@yahoo.com > wrote:
> I have a 40 gram oriented individual with two interesting impact
>"pits". It looks like something struck this meteorite in mid-air.
>Possibly shrapnel from the 5.6 km explosion during its descent. I
>found it a recent gem/mineral show and paid considerably less than it's
>worth.
>
>I want to know if it's common to see these type of scars on other
>Sikhote-Alin specimens.
I wouldn't say "common", but yes, there are examples of S-A meteorites
showing cratering from (presumably) mid-air collisions.
S-A was a unique event; it is the only example I am aware of where a
large meteor survived low enough to actually produce some meteorites
still traveling at cosmic speed right to the ground.
_________________________________________________
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
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