[meteorite-list] Irons DON'T form Fusion Crust's - yes they DO

From: Mr EMan <mstreman53_at_meteoritecentral.com>
Date: Sun, 7 Jan 2007 12:15:34 -0800 (PST)
Message-ID: <747137.91330.qm_at_web51005.mail.yahoo.com>

Thanks for a cogent answer to my comments, Matthias.
We are in violent AGREEMENT. I fear now that I will
soon be the dead messenger beating the dead horse on
this simple issue.

I didn't select the term "glassy" for my argument. I
pointed out that it was quoted from the web site's
definition and that is my main beef. The definition
is not consistent with usage.

I spoke previously about glass in the strict
mineralogical sense. By definition, irons don't have
fusion crusts if fusion crust is limited to only that
material which has glass. Glass doesn't have to look
like a window pane nor does it have to look like
obsidian. Who here disagrees that trinitite,
LDG,tektites, or fulgurites aren't glasses in the
mineralogical sense?

I researched an extensive list of definitions both on
and off line where crust is defined. I also mentioned
a list of appearances that this glass could have and
most of them didn't make the term glass jump to mind
either, e.g. warty, ribbed, net, knobby, whatever. It
isn't the appearance that is at issue. It is the
composition.

Ok is there anyone here that will assert that common
iron meteorites have a crust which has a substantial
component of melted/vitrified/non-crystallized
silicate aka glass? If not then the commonly
published definition of fusion crust is in error OR
logically what is typically found on an iron meteorite
doesn't fit into definition of fusion crust. MY POINT
is we need to redefine FUSION CRUST.

  Now before everyone harumps back in and goes
gnashing their teeth and beating their breasts crying
sacrilege! and Blasphemer!... Please slow down and
reread the two posts. Then tell me where you find
published definition's that address the lack of glass
on an iron's surface. Buchwald didn't "define" fusion
crust in what Svend quoted, I am curious what his
glossary said.

Put another way, fusion crust in the literal root word
sense encompasses all types of meteorite ablation
surfaces. Add the qualifier of "glass" and it goes
contrary to all every glossary I have found.

Regards,
Elton


--- Matthias B?rmann <majbaermann at web.de> wrote:

> Thanks, Svend, Elton,
>
> for contributing interesting aspects to the
> discussion.
>
> For me it's quite surprising that several sources
> use the expression "glassy" (rind, coating,
exterior) for defining fusion crust. Okay, "glassy"
> is perfect for describing the character of many
> tektites such as moldavite or Libyan desert glass
(sic).
>
> But it doesn't hit the point regarding meteorites.
> "Glassy" evokes the impression of something shiny,
very smooth, mirror-like. But as we all now
> (and desire for) a fresh fusion crust creates a
> surface which is mat, like velvet, or untreated
leather, or skin of the shark.
> This is evident what concerns stones, but also in
the case of irons(their crust of course is
> smoother, but nevertheless mat - see relatively
> fresh found Sikhotes).
>
> A "glassy", or shiny, smooth stone meteorite always
> will be the result of
> wind and sand polish. And a shiny Sikhote always
> will need a little help of
> a friend to shine.
>
> Best regards,
>
> Matthias Baermann
Received on Sun 07 Jan 2007 03:15:34 PM PST