[meteorite-list] Meteorite Hunters Find Rare Booty in African Desert (NWA 998 & NWA 1195)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:04:49 2004
Message-ID: <200205171756.KAA15223_at_zagami.jpl.nasa.gov>

http://www.space.com/scienceastronomy/solarsystem/mars_meteorite_020517.html

Meteorite Hunters Find Rare Booty in African Desert
By Heather Sparks
space.com
17 May 2002

The Western Sahara, a fertile hunting ground for enthusiasts seeking
meteorites, offered up two rare Martian rocks in the past few months.

The discoveries bring the total of all known Martian meteorites to
twenty-six. (Meteorites are smallish rocks from space that fall to Earth. If
they don't impact, they are meteors.)

Of the two, one is a rock that is unique to Mars, called nakhlite. Nakhlite
is composed of pyroxene, a mineral common to Earth rocks, but a nakhlite's
ratio of calcium, magnesium and iron in its pyroxene is what makes it
unique.

Of all the known Martian meteorites, only five other nakhlites were
discovered. The age of this nakhlite, named NWA 998, is still unknown but
all the others like it are more than one billion years old.

The other new meteorite has been named NWA 1195, and is a volcanic rock
called shergottite of which there are now 12. They are all thought to be
closer to 200 million years old.

Scientists hope that by studying Martian meteorites our understanding of the
Red Planet's geological history will broaden. Yet, this is no simple task,
said Anthony Irving the project's geologist.

"When you try to describe a planet from twenty-six samples, it's like trying
to learn about the geology of the Peekskill Mountains by looking at the
pebbles in a river 50 miles away," he said.

Still, to Irving and fellow geologist Scott Kuehner of the Earth and Space
Science Department at the University of Washington who collaborated with
brothers Adam and Greg Hupe of Seattle, and two separate Saharan nomadic
groups, recovering and studying these recent specimens is worth the
struggle.

What they're going on, is the theory that two separate catastrophic
collisions from a comet or asteroid must have occurred on Mars to send these
masses to Earth. The characteristics that these rocks share, and those they
do not, are studied in depth to glean a better understanding of the events
and Mars, Irving said.

So far, the scientists know that both of the meteorites are igneous rocks,
meaning they formed on Mars from molten magma that eventually cooled and
solidified. The nakhlite must have formed underground, while the shergottite
was probably extruded in a lava flow.

Knowing the path these meteorites took to get here is another variable that
begs to be answered. However, it is unclear where nakhlite NWA 998 landed.

The Hupe brothers purchased that stone at the Tucson Gem and Mineral Show in
Feb 2002 from dealers who bought it from Western Saharan nomads. The
meteorite most likely came from Western Algeria, but the Berber people who
originally found it will not reveal the location of its discovery, and
despite a secondary search no more nakhlite has been recovered.

The shergottite NWA 1195 was recovered with much more accuracy because the
Hupe brothers actually taught their rock dealers in Morocco how to look for
Martian stones among the batches of Earth rocks found in the desert. The
difference between the two is often slight. Meteorites are usually magnetic,
but Martian rocks are not, or only slightly magnetic. This March, Adam Hupe
picked out NWA 1195 among a pile of Earth rocks in a shipment that arrived
in Seattle.

When Irving and Keuhner's scientific inspection verified the rock was indeed
a Martian shergottite, they realized it had broken off a larger piece after
it had landed on Earth.

A search for the other piece ensued. The dealers in Morocco had recorded
where the rock came from and soon a much larger stone was found 15 meters
away from the original finding in the Safsaf region of Eastern Morocco. The
original piece fit perfectly.

Still, the findings are just two of 26 stones from Mars. And if Irving and
enthusiasts like the Hupe brothers have anything to say about it, the search
for more clues to the Red Planet's catastrophic history will continue right
here on Earth for a long, long time.

"The power for me, is the knowledge you can gain from studying them," Irving
said. "And it certainly is neat to touch these things from other places. "
Received on Fri 17 May 2002 01:56:49 PM PDT