In search of natural quasicrystals

The concept of quasicrystals was first introduced twenty-eight years ago and, since then, over a hundred types have been discovered in the laboratory under precisely controlled physical conditions designed to avoid crystallization. Yet, the original theory suggested that quasicrystals can potentially be as robust and stable as crystals, perhaps even forming naturally. These considerations motivated a decade-long search for a natural quasicrystal culminating in the discovery of icosahedrite (Al63Cu24Fe13), an icosahedral quasicrystal found in a rock sample composed mainly of khatyrkite (crystalline (CuZn)Al¬2¬) labeled as coming from the Koryak Mountains of Far Eastern Russia. In this paper, we review the search and discovery; the analysis showing the sample to be of extra-terrestrial origin; and the initial results of an extraordinary geological expedition to the Koryak Mountains to seek further evidence.