[meteorite-list] Stonirites and Fenirites and crust

From: MexicoDoug <MexicoDoug_at_meteoritecentral.com>
Date: Sun, 7 Jan 2007 15:00:48 -0600
Message-ID: <003801c7329e$eaeef960$b4c85ec8_at_0019110394>

Hello Elton and everyone,

Ah, Elton, then may I ask if the appropriate classes of tektites, have a
"fusion crust" just to make a little more interesting discussion?

After the huge discussion we just had on this very same subject of fusion
crusts for irons, I thought everyone was finally happy:-). Foolish me.

I can only add that while "glassy" certainly applies to silicates, it is not
fair jury either way to cite expert definition where the specific case under
discussion is not clearly (iron meteorites) contemplated for inclusion or
exclusion. There are all kinds of fusion in the literature.

As Buchwald is THE iron reference and addresses irons directly and notes
fusion crust, I don't see anyone ready to crusade against that. If he wants
to call it fusion crust .. well, that's good enough for me.

I will give my own weak, independent defense of why irons can be considered
to have fusion crust. I will not rely on semantics of secondary words used
in definitions by anyone, NASA educators, etc. who come up with lists for
general dissemination, etc.:

Because the words "fusion crust" AT FACE VALUE indicate a residual melt or
mixing of any sort, in the case of meteorites caused by chaotic frictional
heating during entry! Nothing further needed. Metals fuse and silicates
fuse. Solder fuses in joints, welding fuses metals, and even household
fuses are extruded metal filaments which melt ("fuse") upon overly stressing
them. Likewise, the crystalline structure of iron meteorites fuses and
looses its Widmanstatten structures analogous to a stony losing the
definition of chondrules/matrix, etc. Of course I am 100% right (I think),
if I don't put myself in the shoes of the counter augmenters, since I have
chosen what I consider the most logical interpretation that works for me.

But I won't disregard your valid point. It is quite evident you are right
when you say that the rinds are of different composition for Stonirites vs.
Fenirites, regarding the concept of being "glassy". And in order to
distinguish them we need to specify to what type of fusion crust we refer.
There is no confusion in the scientific community as far as I can tell. So
there is no need to standardize here to exclude one or the other. You can't
take a concept like blood, for example and say it doesn't apply to the red,
white or blue stuff, or even Michael's stuff, for example. Just because
when most anyone says the word "blood", we all think of the red stuff first,
unless we happen to be in Tucson during the high season.

Best wishes and good health,
Doug


----- Original Message -----
From: "Mr EMan" <mstreman53 at yahoo.com>
To: "Eric Twelker" <twelker at alaska.net>
Cc: "metlist" <meteorite-list at meteoritecentral.com>
Sent: Sunday, January 07, 2007 1:31 PM
Subject: Re: [meteorite-list] Irons DON'T form Fusion Crust's - yes they DO


I defined glass in a previous post specifically as
that which is formed from fuseing/melting silicates.
Which is closest to your thrid definition of "glassy".
This isn't a discussion of commercial applications of
glass or philosophical ones. You missed the point of
this whole arguement that technical literature defines
fusion crust as containing glass -- the amorphous
state of silicates. There is no manipulation of the
terms by me. I quoted directly from the published
definitions. I used your website in research btw.

Elton
Received on Sun 07 Jan 2007 04:00:48 PM PST