Testing...uno.....dos.......tres
Sorry folks, just testing.
----- Original Message -----
Sent: Friday, January 17, 2003 4:52
AM
Subject: Re: [meteorite-list] New Iron
Meteorite Finds
There are a number of factors that cause the proportion of
irons to vary from place to place. Four important ones are frequency of
pairing of finds, human cultural effects, differential weathering rates, and
recognizability.
Places like NWA produce many, many separately numbered
meteorites that are undoubtedly paired. The same thing happens in
Antarctica. See Marilyn Lindstrom's analysis of this at: http://www-curator.jsc.nasa.gov/curator/antmet/ppr/ppr.htm
By
number, only 1% of Antarctic meteorite finds are irons. When corrected
for extensive pairing among stony meteorites, this percentage rises to near
the 5% value observed among new meteorite falls.
I have also read (I
forget who made this claim) that in areas like the Sahara, iron meteorites are
likely to have been picked up and used as tools by nonindustrial or
preindustrial cultures, whereas stony meteorites were ignored. Maybe one
of you can come up with a reference. This further lowers the percentage
of irons among collections of meteorite finds. It did not, obviously,
affect the Antarctic meteorite population.
The other two effects,
differential weathering and the ease with which finders have recognized irons
compared to stones, probably aren't that important in northwest Africa, Libya,
and Oman. Weathering rates are low, and people know what to look
for. Other places have been greatly affected by these factors, e.g., the
southeast US, where almost all meteorite finds are
irons.
jeff
At 05:34 PM 1/16/2003, ROCKS ON FIRE wrote:
Hello, List,
does anyone know
about how many new irons have been found recently compared to
stony meteorites? It occurs to me that the market gets flooded with
new chondrites every day but hardly any new iron, nut to mention stony
irons. There are more than a thousand L's and H's just from NWA, I
guess. It seems to me that apart from Campo and Nantan (yes, Sikhote and
Brahin too) that stuff is getting rare. And it shows such nice etching
pattern! --
Best regards from DOWN-UNDER,
Norbert &
Heike Kammel ROCKS ON
FIRE IMCA #3420 www.rocksonfire.com
Dr. Jeffrey N. Grossman
phone: (703) 648-6184 US Geological
Survey fax:
(703) 648-6383 954 National Center Reston, VA 20192,
USA
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