[meteorite-list] Feldspar minerals in the inclusions in earthly/lunar basalts

From: mafer_at_domafer.com <mafer_at_meteoritecentral.com>
Date: Thu Apr 22 10:06:14 2004
Message-ID: <00ea01c28782$14fb31a0$6401a8c0_at_vs.shawcable.net>

Hi Bjorn

Minerals, regardless of where they are from, earth, moon or mars, are still
those minerals and as such have properties that will identify them as such.
I guess what I'm saying is that the elements of which the minerals are made
of are the same, no matter if from here or there, and so, the minerals which
are made of them will be made according to the same rules. Some form only
under high presure and temperature, others form onder other conditions of
temperature and pressure. And! some can only form in the presence of water.
So, from these knowns, researchers know that, from extensive evaluation of
earths lava fields and the plutonic outcroppings ( a pluton is magmatic
material which has never been extruded on the surface and is exposed after
millenia of weathering and erosion), the stoney irons cannot be from earth
for we see no occurances of olivine and metal together "on" earth.
Therefore, knowing how they formed individually (temps and pressures) they
summise that these meteorites come from a core mantle boundry. Something we
have not any first hand proof of. Inclusions, on the other hand, of
feldspars, are quite common in cooled magmas and the resulting stone is
called a porphory if the inclusions are large enough to be seen and are
relatively well formed. Other tests, such as fizzing in hcl only provides a
indication that a basic mineral (carbonate or such) is present. The fact
that you, if I'm understanding right, are seeing what appears to be
feldspars, most likely points to a magmatic origin. vesicle size is not a
determinate of being magmatic or not, andesites can often have extemely
small vesicles. And, if I'm not wrong, I believe in Sweden is quite a bit of
plutonic rock, so its probable to be able to find lavas since plutons are
but cooled magma chambers.
Hope this helps, long winded as it is.
Mark
----- Original Message -----
From: Bjørn Sørheim <bsoerhei_at_online.no>
To: <meteorite-list_at_meteoritecentral.com>
Sent: Friday, November 08, 2002 8:22 AM
Subject: [meteorite-list] Feldspar minerals in the inclusions in
earthly/lunar basalts


> Hello list,
>
> Finding an extrusive volcanic(e.g. basaltic) stone in a volcanic field on
> our planet, certainly gives no hint to think it came from the Moon or
> Mars or elsewhere in the solar system.
>
> A bit otherwise when you find such a stone say ~500 km from nearest
> volcanic field.
> In the northern part of Europe(where I live) there of course has been
> ice-ages which redistributed stones by the movement of glaciers, but
> still the possibillity that it could be a meteorite is not entirely out
> of the question.
> The specimen I am looking at is also peppered with tiny holes, about 2mm
and
> smaller.
>
> But the question I have is concerning the feldspar inclusions.
> I wonder what span in %-values there is of Albite(Na) vs. Anorthite(Ca)
> in the plagioclase of these inclusions in the lunar basalts compared to
earthly
> basalts?
> On the practical side (testing) - would a lunar basaltic feldspar
> inclusion fizzle in (cold) hydrocloric acid (HCl)?
> Would a (Vesta) eucrite inclusion have the same values as its lunar
> counterpart?
>
> Regards,
> Bjørn Sørheim
>
>
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Received on Fri 08 Nov 2002 06:53:46 PM PST