[meteorite-list] regmaglypts

From: Alexander Seidel <ase_at_meteoritecentral.com>
Date: Thu Apr 22 09:41:53 2004
Message-ID: <3A521987.759189EB_at_planet-interkom.de>

Donald Blakeslee wrote:
>
> I'm wondering about the two words used to name the depressions formed on
> the surfaces of meteorites during their passage through the atmosphere:
> regmaglypts and piezoglypts. Any difference in the exact meanings? And
> why piezo-, which also shows up in piezoelectric, referring to the kind of
> discharge one can produce in crystalline quartz.

There surely is much more explanation to this around in the literature,
but here is what I found in Buchwald´s "Handbook of Iron Meteorites" in
the description section of the Quesa iron:

"...It was, however, in describing this somewhat atypical meteorite that
Berwerth (1909) introduced the expression "regmaglypts" to cover any
cavity or depression present on the meteorite surface before it landed
on Earth. For a generation another expression "piezoglypt" (from Greek:
... to press of push, ... to cut or engrave) had been in general use. It
had been introduced by Daubree to indicate his experimentally supported
belief that the cavities were produced by the erosive action of
turbulent compression-heated air masses that passed the meteorite in its
fall....

Story-Maskelyne (1876) on the other hand, maintained that all specimens
were formed by spalling during the atmospheric flight. Counter to this
hypothesis, it may be said, among other things, that the majority of
iron meteorite falls do not produce a large number of small fragments in
addition to the major mass such as would be expected from the gradual
degradation of the surface.

Berwerth proposed that the large fracture faces which resulted when
parent meteoritic bodies disintegrated outside - or at an early stage in
the atmosphere - were not plane but were covered with numerous fracture
pits (..), and these pits became modified to regmaglypts during the
flight. In later publications (e.g. Berwerth, 1910), the case was
further examined. The hypothesis is, however, not well founded. The
decisive objection is that the diameter of the regmaglypts is
proportional to the diameter of the residual mass. This fact will be
quite clear from an examination of the descriptions in the present
handbook; the regmaglypts (on the front face) are usually one tenth the
size of the residual mass. Such consonance would not be easy to explain
on the basis of an early uneven fracture face.

Daubree´s view appears to be well-founded. The degradation of the
surface occurs by ablation-heating, melting, vaporization, and in the
last stages also by oxidative burning. Fragmentation and selective
melting of troilite do also occur but are not responsible for the usual
regmaglypts. Nevertheless, it is Berwerth´s word "regmaglypt", that has
won general acceptance in favor of piezoglypt."

Personal note added: have a look e.g. at your Sikhote-Alins individuals
of different sizes, and remember the phrase "The decisive objection is
that the diameter of the regmaglypts is proportional to the diameter of
the residual mass". It can be very well seen here.

Best wishes, and a Happy New Year all,
Alex

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Received on Tue 02 Jan 2001 01:10:15 PM PST