Naturally formed quasicrystals--crystal-like solids with supposedly impossible symmetries--are among the rarest structures on Earth. Only two have ever been found.
A team led by Paul Asimow (MS '93, PhD '97), professor of geology and geochemistry at Caltech, may have uncovered one of the reasons for that scarcity, demonstrating in laboratory experiments that quasicrystals could arise from collisions between rocky bodies in the asteroid belt with unusual chemical compositions.