[meteorite-list] newbie question

From: Graham Ensor <graham.ensor_at_meteoritecentral.com>
Date: Tue, 30 Jan 2018 17:36:15 +0000
Message-ID: <CAJkn+kYB9nFV4aTNsxQ5GEQF_MTh-B-Q0x_38iwpZPYR9GU4uQ_at_mail.gmail.com>

Hi Lloyd..."stable" refers to a meteorite which under normal circumstances
does not deteriorate rapidly due to mainly humidity and oxidation...usually
of the Nickel Iron contained within the sample. Some meteorites almost self
destruct in any conditions where moisture from the air can come in contact
with the matrix. Mostly controlled by keeping them dry using desiccant in
cabinets or boxes or dehumidifiers...coating sometimes help but can
sometimes trap moisture and make the situation. An example might be the
pallasites Brahin and Seymchan....Brahin tends to be very unstable and ends
up as a pile of rust and olivine in many collections if not strictly
comtrolled whereas Seymchan tends to be much more stable and can withstand
higher humidity....instability can vary in the same types/classification
depending on the types of ground they have been lying in for years before
being found...e.g. some Campos. When iron in meteorites starts to rust and
ooze out brown liquid it is called Lawrencite disease.

Thumbprints are the various shaped dimples often found in ablated surfaces
of meteorites due to the variations either of the matrix or plasma ball
around the meteorite in hot flight...the technical name is
"regmaglypts"....the patterns and size of these varies depending on the
size of meteorite and the orientation...they can be quite random or just
cover small parts of the fusion crusted areas....if the meteorite stays
oriented and does not tumble then these regmaglypts can form flowing
elongated dimples travelling away from the leading face of the meteorite.

https://commons.wikimedia.org/wiki/File:Meteorit_Cabin_Creek_nhm-Wien.jpg

http://www.culture24.org.uk/science-and-nature/art74972

https://en.wikipedia.org/wiki/Thumbprint_(disambiguation)#/media/File:Murnpeowie_meteorite.jpg

Hope that helps...

Graham





On Tue, Jan 30, 2018 at 1:51 PM, Lloyd Alexander via Meteorite-list <
meteorite-list at meteoritecentral.com> wrote:

> I have a couple questions that probably show my "newbie" stats but you
> can't learn without asking.
>
>
> What do "stable" and "thumbprints" mean?
>
>
> Lloyd W. Alexander
> Photographer, Painter, and Author
> _at_Lloyds_Journey
> http://lloydsjourney.com
>
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Received on Tue 30 Jan 2018 12:36:15 PM PST