Brilliant X-ray source assists in the discovery of a novel stable high-pressure form of silica with a pyrite-type structure

The mineral silica (SiO₂) is a common substance that is a constituent of all of the planets in our solar system. At SPring-8, Harima, Japan, Dr. K. Hirose (Tokyo Institute of Technology; Japan Agency for Marine-Earth Science and Technology) and his co-workers recently found that, above 268 GPa and 1800 K, silica exhibits a novel stable high-pressure form with a pyrite-type structure, which is much denser than other known silica phases. This form of silica could be one of the main constituents of the core of a gas-giant planet such as Uranus or Neptune. For more information, see the paper, "The Pyrite-Type High-Pressure Form of Silica", Y. Kuwayama et al., Science, 309, 923-925 (2005).