from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A high-pressure polymorph of silica found in extreme conditions such as the impact craters of meteorites, with the chemical composition of silicon dioxide, SiO2.


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  • These other forms of silica include opal, chalcedony, flint and chert (non-crystalline), and cristobalite, tridymite, coesite, and stichovite.


  • Shoemaker, who wrote his doctoral thesis on the crater, was renowned for his work on extraterrestrial impacts and the mechanics of meteorite impacts, and for his co-discovery of coesite, a shocked form of quartz rarely found naturally on Earth.

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