[meteorite-list] Finding fossil Meteorites

[MEM]

Hello Bernd,
I believe those numbers are from a specific incident and may have been those 
found in the tiles on the floor where they were first identified by an astute 
geologist attending a function there.  They were subsequently traced back to one 
quarry ( Brunflo?)  Subsequently many more were found at several quarries in 
Sweden.

I agree regarding the mineralogy of fossil meteorites and probably depletion of 
expected elements. Knowing what I think I know about typical meteorite fabric, 
deep weathering, taphonomy , and secondary mineral formation(wink wink) any 
fossil meteorite will likely be depleted of the normal, hallmark, 
minerals/elements via normal leaching.  For example, I think nickel is more 
mobile than we ordinarily believe and  it will probably be carried away to form 
the microscopic  hair-like crystals ( aka accular) of the mineral "millerite" or 
even a nickel carbonate gaspetite(?) which might be missed on casual 
observation. Another example might be the pyroxines. They weather into a very 
"non-mineral looking" flexible sheet of the mineral palygorskite also know as 
mountain cork/leather, and so on.  Fossil meteorites may retain meteorite 
character in composition or in  form with no original mineralization or easily 
recognizable meteoric  shale ( e.g. Sardis Iron, Georgia, USA). I'd be curious 
as to the nickle content of that shale, or Lake Murry shale compared to Lake 
Murry iron proper.  That should give a glimpse into migration tendencies of 
siderophile elements out of the matrix over a span of 115 million years anyway.

I have not attempted to compile a list of secondary mineralization for the 
minerals found in meteorites but, thinking into what the associated minerals 
might be and, how they form is intriguing, as another diagnostic clue into 
bombardment rates in the past. 


 I recall a study into past bombardment rates, and the Ordovician was one marked 
by high impact rates.  In fact just this week was a report that a 120km 
crater/(cluster of craters) of Ordovician age was found in Australia.  I know 
there were several major impacts in the Cretaceous well before Chuxilub and I 
seem to recall a higher rate of bombardment in the Carboniferous as well.

I believe that there are relatively lots of fossil meteorites in situ only the 
people most closely connected with exposing them aren't looking for meteorites. 
They just hit "bad rock" and send it to the dregs/crushing pile and move on.  
The candidate specimens I've collected, were found because I spent a lot of time 
in the field and in the books and kept a look out for rocks that somehow didn't 
fit the normal for where they were found.  Pretty much how we hunt surface 
meteorites.

Back to the limestone quarry(s) where the Ordovician specimens were found in 
Sweden. There have been many found at different quarries in there and probably 
reflect sustained worldwide bombardment in my opinion owing to the successive 
depths they were found at. 
<http://epsc.wustl.edu/~visscher/research/fossil_files/frame.htm>

 I believe many were discarded prior to the recognition that they were 
meteorites.  The layer they were concentrated in made for poor polishing and 
hauled off to a remote section of the quarry for crushing.  I believe the report 
of 3-5-8 or whatever the number, was the number  originally found in the 
marble/limestone tiles on the floor of a  building where an astute visitor 
recognized them as such.  They were then tracked back to the quarry.  I thought 
about 60 or more were recovered , the article says 25 from a particular quarry.

 Here is a blurb from a web page.  
<http://www.science-frontiers.com/sf125/sf125p07.htm>

Fossil Meteorites
Over a century ago, astronomer H.W.M. Olbers (of Olbers Paradox fame) remarked 
that meteorites are extremely  rare in the fossil record. While meteorites are 
found in profusion in some specially favored surface deposits  (Antarctica and 
Australia's Nullarbor Plain), there are very few records  of any being found in 
the immense volumes of coal, gold ores, and other geological materials  that 
have been mined down the centuries. Of course, many meteorites  escaped the 
notice of miners who were looking for something else. Nevertheless, few  have 
been reported from strata more than a few thousand years old. (See ESI8 in 
Neglected Geo logical Anomalies.)  It is therefore surprising  that a veritable 
lode of fossil meteorites has been found in a limestone  quarry at Kinnekulle, 
in southern Sweden. 

"During the sawing  of a few thousand cubic meters of Ordovician limestone into 
2-3 cm  thick slices, 25 fossil meteorites have been found. All meteorites, 
except, four, have been found in a 60 cm thick bed called  the Archaeologist. 
This bed represents a few hundred thousand years and contains several hard 
ground surfaces...Many of the Archaeologist meteorites are prominently angular 
in shape whereas others are round. This seems difficult to reconcile with an 
atmospheric breakup of a single large meteorite." 

B. Schmitz and M. Tassinari, the  authors of this paper, suggest that this rare 
concentration of fossil  meteorites represents an unusual event in the solar 
system history, possibly a major collision in the asteroid belt. 

(Schmitz, Birger, and Tassinari, Mario; "Early Ordovician Meteorites: How Many 
Falls?" Eos, 79:F50, 1998.) 

Comment. It should be  added that tektites and microtektites (impact debris) are 
likewise  found mainly in recent, superficial deposits, even though many ancient 
impact craters are now recognized on earth. 


Finally, I note a site for catalogs of scientific anomalies which includes the 
Ordovician Meteorite Occurrences in Sweden. 
<http://www.science-frontiers.com/sourcebk.htm>

Regards
Elton

----- Original Message ----
> From: "bernd.pauli at paulinet.de" <bernd.pauli at paulinet.de>

> Considering the high degree of terrestrialization of  Ordovician/fossil 
>meteorites
> (usually the chromite content is the only hint  it once was meteoritic) and 
>also
> considering the extremely low number (5 or  6?) of fossil meteorites found so 
>far,
> it is highly unlikely a meteorite  collector will ever find a fossil meteorite 
>in situ.
> 
> Regards,
> 
> Bernd
> 
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