Mark, Carl, List,
I've scoured the web looking for photographs of andesite and see "some"
resemblance but not something conclusive for identification of this
stone. Though it does looking similar. I'm not asking if this is a
metoerite, I'm asking if it's NOT a meteorite, what is it?
As we know fusion crust is one of the biggest identification factors
considered in the ID of meteorites. (I can see where this is going) and
there are literally hundreds of examples of different textures, and
thicknesses, and visual variances in fusion crust that it's not funny.
Which is why we have other tests we use to properly identify a rock as a
meteorite.
Now before all you guys jump on me for asking the dreaded "Is this a
meteorite?" question or yell at me about how to identify a meteorite,
I'd like to clarify a few things. This is a "ROCK" to me, nothing more.
I've examined literally thousands of meteorites and thrown away tens of
kilos of terrestrial stones that somehow got mixed into batches of
meteorites I've purchased. So the probability of this ROCK being a
meteorwrong is there.
When you consider the sheer numbers of meteorites that I've examined,
it's no wonder that from time to time I will come across a stone like
this that perplexes me and makes me say "What the heck is that?". I have
two good sized drawers FULL of meteorwrongs that I look through every
now and then just to see if I can pull out a few real meteorites as my
knowledge of meteorites grows.
Here's a NICE meteorite I recently found in my meteorwrong drawer:
EXTERIOR: http://www.meteoritesusa.com/images/odd/odd-1e.jpg
INTERIOR: http://www.meteoritesusa.com/images/odd/odd-1a.jpg
I get a whole bunch of odd rocks, and only post to the list when I can't
find an answer myself. Believe me I look for answers long before I post
any photos of meteorwrongs. Here's some examples of some that I've
either never posted and/or only asked privately for advice on.
SAMPLES OF ODD ROCKS: http://www.meteoritesusa.com/odd/meteorwrongs.htm
The point is this new ODD ROCK is just that. Odd. If anyone can tell me
what it is, or perhaps show me some comparable photos that would be great.
This stone http://www.meteoritesusa.com/odd/ was in a batch of
meteorites I purchased. I can guarantee that if you were to hold this
stone in your hand and look at the "crust" that seems to on this piece,
you'd say "Hmmm" too. The photos though good, do not do justice to it,
and I imagine that' why people don't go around identifying meteorites
from photos... ;)
Regards,
Eric Wichman
Meteorites USA
[email protected] wrote:
-Mark,
This is one of the things I miss most about David Kring being out of the Biz of
classifications. He was the one that was always willing to take the time to
show you and explain exactly what you were looking at. He is with NASA now But
he used to frequent the Tucson show when he lived here.
To your other points; It seems to me the question was "is this a meteorite"? IMHO I see a rock that could be one if it came from space. So, is that fusion crust or not? David showed me multiple examples of Desert varnish It actually looks very little like fusion crust. Desert varnish is very thin and being just a residue of manganese it is very dull or flat black and rarely shiny. Whereas fusion crust always has some heft to it. you can easily see real thickness on a cut section. It is always a measurable thickness where Desert varnish requires a microscope to see it's thickness. Another imposter is Magma stuck to the outside of the rock. Magma is usually too thick to be fusion crust but again fairly easy to recognize once a you have seen the difference in person. To this point I wish Science would recognize that some of us do know this and would never confront them unless we had considered these factors.
So, I ask is this fusion crust I see? Where was it found? Was it on the living room floor under a big hole in the roof or was it in a field with no other rocks around? Mars for example has plenty of basalt and andesite. IMy 2 cents.
Carl Esparza
IMCA 5829
--- Mark Bowling <[email protected]> wrote:
I was mostly going by color. Basalts tend to be darker, and granitic rocks are
very light in color. But it's really hard to look at photos... Having it in
hand would be much easier (a necessity really).
I would be interested in learning what a professional would consider when faced
with such a rock... It would be cool if someday the IMCA could host an ID
workshop, maybe one year at Tucson or one of the European shows (where you're
guaranteed a group of possible participants).
Mark
--- On Wed, 5/20/09, Michael Fowler <[email protected]> wrote:
From: Michael Fowler <[email protected]>
Subject: Re: [meteorite-list] Meteorite or Meteorwrong?
To: [email protected]
Cc: "Michael Fowler" <[email protected]>
Date: Wednesday, May 20, 2009, 7:20 AM
Most andesites have
phenocrysts. This one doesn't. Still could be
andesite, but maybe not.
Mike Fowler
Chicago
Mark B.>>I'd have to say andesite (definitely
not granite). <<
Well...after some page turning and googling etc, I
have to now agree with
Mark that this rock is probably some sort of
andesite...and definitely not
granite. I've never seen so many different rocks that
I formerly simply
referred to as granite. :O) I haven't found a totally
matching photo of
andesite to the photo eric referred to, but the
literature gave me the impression
that andesite is what he has or is at least a good
guess.
GeoZay
Looks like a fine grained basalt covered with
desert varnish.
I see no fusion crust (flow lines etc.) and no
regamaglypts. In the
cut surface, no metal, no chondrules, and no heat
affected zone.
Mike Fowler
Chicago
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--
Regards,
Eric Wichman
Meteorites USA
http://www.meteoritesusa.com
904-236-5394
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