FW: [meteorite-list] Discovery of a Double Impact Crater in Libya

From: Charles Viau <cviau_at_meteoritecentral.com>
Date: Thu Apr 22 10:18:02 2004
Message-ID: <003701c3c6e1$e4bd2c50$1800a8c0_at_chupa>

Sterling, Norm and List..

That is really interesting. It follows that for a meteorite impact to
make glass, there has to be some rather special conditions.

I got some information on how people made the cheapest green glass, over
a hundred years ago. Look at the ingredience they used:

------------------------------------------------------------------------
------------------------------------------------
Common green bottle-glass is made from 200 lbs. of wood-ashes and 100
lbs. of sand, or 170 lbs. of ashes, 100 lbs. of sand, and 50 lbs. of the
slag of an iron furnace; these materials must be well mixed.

The materials for making glass must first be reduced to powder, which is
done in mortars or by horse mills. After sifting out the coarse parts,
the proper proportions of silex and flux are mixed together, and put
into the calcining furnace, where they are kept in a moderate heat for 5
or 6 hours, being frequently stirred about during the process. When
taken out the matter is called frit. Frit is easily converted into glass
by only pounding it, and vitrifying it in the melting pots of the glass
furnace;

Bottle-glass is the coarsest and cheapest kind, in this little or no
fixed alkali enters the composition. It consists of alkaline earth and
oxide of iron combined with alumina and silica. In this country it is
composed of sand and the refuse of the soap-boiler, which consists of
the lime employed in rendering this alkali caustic, and of the earthy
matters with which the alkali was contaminated. The most fusible is
flint-glass, and the least fusible is bottleglass
------------------------------------------------------------------------
-------------------------------------------------

So,
>From this info, it seems that for a large meteorite impact to make rough
glass, there needs to be the basic ingredience available to make this
stuff called 'frit'. In cheap glass, oddly enough, it is burnt wood
ashes, sand and iron slag ! Perhaps, in order for a meteorite impact
to produce glass, you need a forested area, high silica and/or lime
content (limestone, sandstone) and Melted Iron (the Iron from a
meteorite). It could be said that a swampy area with a
sandstone/limestone bedrock is an IDEAL place , if it was hit by an Iron
!!!!

I am sure the chemical processes are much more complicated that this,
but understanding how rough glass can be made with materials like this
was a fun exercise.

CharlyV

-----Original Message-----
From: Sterling K. Webb [mailto:kelly_at_bhil.com]
Sent: Saturday, December 20, 2003 1:14 AM
To: 'Meteorite Mailing List'
Cc: Charles Viau
Subject: Re: [meteorite-list] Discovery of a Double Impact Crater in
Libya

Hi, Charles,

    That was my question exactly!
    First, they are close enough for the LDG to come from them, no
further
than moldavites to the Ries.
    Second, they're big enough to be the source.
    The real question is "How old are they?" LDG is 28.x million years
old.
The article says the surface is Cretaceous sandstone covered with recent
soils, so the craters are more than a couple of million years old and
younger than 62 million years.
    The other funny thing is at that point in time (28-34 million years
ago)
this area was a swamp in the process of drying up. The high silica
content
of LDG suggests they were formed from sand.

Sterling K. Webb
------------------------------------------------------------------------

---
Charles Viau wrote:
> Fantastic!
> The somewhat obvious question is that could these structures possibly
be
> a source for Libyan Desert Glass, or is the source for that material
> already well known?
>
> CharlyV
>

Received on Sat 20 Dec 2003 05:13:15 AM PST