[meteorite-list] What weather!

From: mafer <mafer_at_meteoritecentral.com>
Date: Thu Apr 22 10:23:42 2004
Message-ID: <006301c2dfbd$37856fe0$6501a8c0_at_vs.shawcable.net>

Hi David

Weathering is a rating on how bad the elements have been to a meteorite
after it has arrived on Earth. W-0 being no weathering and W-4 being the
worst. Its interesting how meteorites found in different parts of the world
can "weather" so well, while others only need a sniff of moisture and they
start to degrade. But its all relative to the localities climate. Nantans
are bad about rusting (they don't come from a nice dry climate like the
Sahara's do.
Weathering appears, from just what I have read about it, an adoption (and
major modification of), of an effect noted in the late early to mid 20th
century, in volcanic glass. Especially that used for tools by native
peoples. The glass would develope a "rind" which when "calibrated" for local
conditions, could be used to date the tools. The rind developed from
moisture around the glass, (and in extreme cases, devitrification occurs,
but I'm not 100% sure that UV radiation from the sun doesn't also play a
role). So, by noting the amounts of products (like oxides and sulfides, but
not limited to the metals) to parent materials (like nickel and iron), one
can impart a ranking based on the decomposition of the meteorite.
Although I have a few books right here (including Dodd's Meteorites from my
schools library) none go into weathering other than mentioning it.
And so, I hope I've given you a good answer and my information is sound. I'm
confident of the actual rating sequence (0 being least and 4 being worst).
And, since its not used as a dating tool, it can be expanded to be a general
rating world wide.
Mark
----- Original Message -----
From: David Freeman <dfreeman_at_fascination.com>
To: meteorite-list <meteorite-list_at_meteoritecentral.com>
Sent: Friday, February 28, 2003 9:47 PM
Subject: [meteorite-list] What weather!


> Dear List;
> Could or would anyone like to offer any short explanation of the
> different weathering grades. W1 to W 4, which is freshest, and any
> criteria for each? I am too tired and lazy to hunt up the information
> at the moment.
> Thank you in advance,
> Dave Freeman
>
>
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Received on Sat 01 Mar 2003 01:38:13 AM PST