Natural Quasicrystals
Luca Bindi,1
Paul J. Steinhardt,2,*
Nan Yao,3
Peter J. Lu4
Quasicrystals are solids whose atomic arrangements have symmetries
that are forbidden for periodic crystals, including configurations
with fivefold symmetry. All examples identified to date have
been synthesized in the laboratory under controlled conditions.
Here we present evidence of a naturally occurring icosahedral
quasicrystal that includes six distinct fivefold symmetry axes.
The mineral, an alloy of aluminum, copper, and iron, occurs
as micrometer-sized grains associated with crystalline khatyrkite
and cupalite in samples reported to have come from the Koryak
Mountains in Russia. The results suggest that quasicrystals
can form and remain stable under geologic conditions, although
there remain open questions as to how this mineral formed naturally.
2 Princeton Center for Theoretical Science, and Joseph Henry Laboratories, Department of Physics, Princeton University, Princeton, NJ 08544, USA.
3 Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, NJ 08544, USA.
4 Department of Physics and School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
* To whom correspondence should be addressed. E-mail: steinh{at}princeton.edu
