Researchers report evidence of diamond formation from ankerite, a ferromagnesite carbonate, in the Xiuyuan Meteoritic Crater in China as a result of spontaneous reduction of carbonate to carbon by iron in the ankerite--without melting and at pressures of 25-45 GPa and temperatures of 800-900°C generated by meteoritic impact; the findings suggest that such a process could potentially form abundant diamond in Earth's lower mantle, where similar pressures and temperatures are found.
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Article #17-20619: "Natural diamond formation by self-redox of ferromagnesian carbonate," by Ming Chen, Jinfu Shu, Xiande Xie, Dayong Tan, and Ho-kwang Mao.
MEDIA CONTACT: Ming Chen, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, CHINA; tel: +86-20-8529-0255, +86-13640241194; e-mail: mchen@gig.ac.cn
Proceedings of the National Academy of Sciences