[meteorite-list] Re: petrological grade....(H3.0--H3.9)

From: E.L. Jones <jonee_at_meteoritecentral.com>
Date: Thu Apr 22 09:46:25 2004
Message-ID: <3B0C6105.35CBB1BE_at_epix.net>

Frank Cressy answered this recently, presented here from his message.
Elton

Petrographic grades 3.0 through 3.9 are obtained by measuring changes of
thermoluminescence (TL) of chondrules. TL measures the luminesence of the
sample after it is irradiated.

During mild metamorphism, tiny grains of feldspar start to grow in a glassy
chondrule. The higher the metamorphism, the more feldspar is present and
feldspar causes a marked increase in thermoluminence. This allows one to
subdivide the petrographic grade 3 meteorites.
Hope this helps.
Regards,
Frank

entropydave wrote:

> hello,
> I wonder if someone can explain the decimal pet grades such as H3.4 or H3.7?
> yours curiously...
Received on Wed 23 May 2001 09:17:06 PM PDT