[meteorite-list] shock help?

From: mafer_at_domafer.com <mafer_at_meteoritecentral.com>
Date: Thu Apr 22 10:06:18 2004
Message-ID: <002c01c295cf$a1cf9520$6401a8c0_at_vs.shawcable.net>

Hi Tom

Well, I did learn a little in school (and am looking for work) and try to
pass it on as I can. There are the other more fundamental checks you can do
like magnetism and metal detector testing (of course, these will only work
with some metal present). If you have a rock saw (you can almost always find
a rock or mineral club in any town larger than one stop light and they are
always willing to help determine a rocks identity), you can slice it and
look for more tell-tale signs like chondrules and metal flecks and
breciation.

Mark


----- Original Message -----
From: Tom / james Knudson <peregrineflier_at_hotmail.com>
To: <mafer_at_domafer.com>
Sent: Tuesday, November 26, 2002 8:36 PM
Subject: Re: [meteorite-list] shock help?


> Wow, That was quite an explaination! I am going to keep that one. I don't
> know if it will help me figure out if this rock is a meteorite or not, it
is
> so confusing to try to know if it is a meteorite or not!
>
>
> Thanks, Tom
> The proudest member of the I.M.C.A. #6168
>
>
>
>
> From: <mafer_at_domafer.com>
> To: "Tom / james Knudson" <peregrineflier_at_hotmail.com>
> CC: <meteorite-list_at_meteoritecentral.com>
> Subject: Re: [meteorite-list] shock help?
> Date: Tue, 26 Nov 2002 19:21:50 -0800
>
> Hi Tom and list
>
> Well, your sure digging correctly. Actually, terrestrial rock can show
> minute "fractures" and crack from a variety of things such as, but not
> limited to: earthquake, volcanic eruption and weathering. Now whats
> interesting about weathering is that it take a wide variety of forms.
Quite
> often, "shocked" quartz grains are found in volcanicly derived "green"
sand
> layers and are a result of the eruption itself. The simplest forms we see
> are the wind scoured rocks like sandstone or water worn pebbles (which is
> actually a tumbling grinding effect and not so much to do with water doing
> the grinding away, but the tumbling on rocks against themselves). Less
> realized are the freeze-thaw effects which can most easily be seen on
> exposed plutonic rock such as seen in Yosemite in Ca. or Stone Mountain in
> Ga. which causes the rock to break apart and almost looks like orange
peels
> till it slides down into a talus slope of rubble. Freeze-thaw also causes
> most of the falling rock around the continent for which the dot puts up
the
> "watch for falling rock" signs. And basicly, what happens here is that
> moisture gets into minute crevices of the rock and when it freezes, it
> expands, then it thaws in the spring and is repeted till the chunk of rock
> gives way to gravity and heads toward the road. Now, about these minute
> crevices. They can be from a few things, one of which is acid rain. Not
> something only invented by 20th century man, it has been around as long as
> rain has and happens every time there is any volcanic activity which
places
> acids into the atmosphere. This acid rain accounts for a lot of long term
> weathering and will attack the carbonates first which is often the
cementing
> agent in sedimentary rock. It also attacks the silica cements in many
types
> of rock, just not seds, but metamorphic and volcanic rock too. Water too
can
> disolve as its a polar solvent. So, to finally answer your initial
question,
> fractures are found in terrestrial rock all the time and in order to
> determine if its from shock or weathering, one needs to look at the frains
> of the rock itself, not the cracks, for a shock fracture of any kind, be
it
> terrestrial or extra-terrestrial, will not just go around the grains
> (crystals ), but will go through them if thats the easiest path to
relieving
> the stress of shock.
>
> Mark
>
>
>
> ----- Original Message -----
> From: Tom / james Knudson <peregrineflier_at_hotmail.com>
> To: <meteorite-list_at_meteoritecentral.com>
> Sent: Tuesday, November 26, 2002 6:55 PM
> Subject: [meteorite-list] shock help?
>
>
> > Hello List, pardon me for picking your brains! I have a meteorite
> hopefull
> > that if you look at it with a loop at an angle in good light you can
see
> > that the stuff that makes up the mass of the rock has small cracks
 only
> > visible with a loop) all through it. Every thing looks like it has been
> > shattered. Now then, Is this shock? Do or can terrestrial rocks have
> these
> > tiny cracks all through them?
> >
> >
> > Thanks, Tom
> > The proudest member of the I.M.C.A. #6168
> >
> >
> >
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Received on Tue 26 Nov 2002 11:44:10 PM PST