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Re: tektite / impactite
- To: Impactika@aol.com, meteorite-list@meteoritecentral.com
- Subject: Re: tektite / impactite
- From: FERNLEA4@aol.com
- Date: Thu, 4 Nov 1999 05:42:43 EST
- Old-X-Envelope-To: <meteorite-list@meteoritecentral.com>
- Resent-Date: Thu, 4 Nov 1999 05:43:48 -0500 (EST)
- Resent-From: meteorite-list@meteoritecentral.com
- Resent-Message-ID: <JGd5OD.A.8JF.GNWI4@mu.pair.com>
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In a message dated 04/11/99 03:52:56 GMT Standard Time, Impactika@aol.com
writes:
<< Since the list is (relatively) quiet and the last subject of discussion
was
Tektites, may I ask a question:
Could any of you give me a precise, clear-cut definition of "Tektite" and
"Impactite", and the exact difference between the 2. >>
Hi Anne & List,
I was reading Guy Heinen's book "tektites - witnesses of cosmic catastrophes"
late last night which gave a comparison between impact glasses and tektites
(not including the layered, Muong Nong types). I don't have the book with me
right now so I'm working on memory, but it goes something like this......
# Both impact glasses & tektites are products of a high energy impact event
but the two differ greatly in the following ways:
# Water content is ~10 times higher in impact glasses than that found in
tektites.
# The gas bubble pressure within tektites corresponds to an altitude of up to
70km, whereas the gas pressure of impact glass is at surface level.
# Tektites are formed from the upper rock layers and mineral inclusions are
rare - impact glasses are formed from much deeper rock layers and mineral
inclusions are common.
# The meteoritic content within impact glass is far higher than that found in
tektites.
# Tektites are found in distinct strewnfields away from the crater, whereas
impact glasses are found nearby, distributed around and within the crater.
# All (almost all?) impact craters produce impact glass - only 4 impact
craters have been shown to produced tektites.
# Impact glasses are irregular without aerodynamic shapes - tektites are more
regular and aerodynamic shapes are common, suggesting that tektites have
flown and ablated during high speed atmospheric passage.
That's about all I can remember....apologies for any errors! Maybe one of our
tektite buffs can expand/add/correct some of these points?
Cheers,
Rob Elliott.
Fernlea Meteorites
http://hometown.aol.com/fernlea4/forsale.html
Milton of Balgonie,
Fife. KY7 6PY
United Kingdom
Tel: +44-(0)1592-751563
Fax: +44-(0)1592-751060
Email: FERNLEA4@aol.com
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