[meteorite-list] Nobel Prizewinning Quasicrystal Fell From Space

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue, 3 Jan 2012 10:56:33 -0800 (PST)
Message-ID: <201201031856.q03IuXbj006916_at_zagami.jpl.nasa.gov>

http://www.newscientist.com/article/dn21325-nobel-prizewinning-quasicrystal-fell-from-space.html

Nobel prizewinning quasicrystal fell from space
by David Shiga
New Scientist
January 3, 2012

A Nobel prizewinning crystal has just got alien status. It now seems
that the only known sample of a naturally occurring quasicrystal fell
from space, changing our understanding of the conditions needed for
these curious structures to form.

Quasicrystals are orderly, like conventional crystals, but have a more
complex form of symmetry. Patterns echoing this symmetry have been used
in art for centuries, but materials with this kind of order on the atomic
scale were not discovered until the 1980s.

Their discovery, in a lab-made material composed of metallic elements
including aluminium and manganese, garnered Daniel Shechtman of
the Technion Israel Institute of Technology in Haifa last year's Nobel
prize in chemistry.

Now Paul Steinhardt of Princeton University and colleagues have evidence
that the only known naturally occurring quasicrystal sample, found in a
rock from the Koryak mountains in eastern Russia, is part of a meteorite.

Nutty conditions

Steinhardt suspected the rock might be a meteorite when a team that he
led discovered the natural quasicrystal sample <http://dx.doi.org/10.1126/science.1170827>
in 2009. But other researchers, including meteorite expert Glenn MacPherson
of the Smithsonian Institution of Washington DC, were sceptical.

Now Steinhardt and members of the 2009 team have joined forces with
MacPherson to perform a new analysis of the rock, uncovering evidence
that has finally convinced MacPherson.

In a paper that the pair and their teams wrote together, the researchers
say the rock has experienced the extreme pressures and temperatures
typical of the high-speed collisions that produce meteoroids in the
asteroid belt. In addition, the relative abundances of different oxygen
isotopes in the rock matched those of other meteorites rather than the
isotope levels of rocks from Earth.

It is still not clear exactly how quasicrystals form in nature.
Laboratory specimens are made by depositing metallic vapour of a
carefully controlled composition in a vacuum chamber. The new discovery
that that they can form in space too, where the environment is more
variable, suggests the crystals can be produced in a wider variety of
conditions. "Nature managed to do it under conditions we would have
thought completely nuts," says Steinhardt.

Journal reference: /Proceedings of the National Academy of Sciences/,
DOI: 10.1073/pnas.1111115109 <http://www.pnas.org/>
Received on Tue 03 Jan 2012 01:56:33 PM PST