Related Experiment Video
Updated: Feb 14, 2026

Calcium Carbonate Formation in the Presence of Biopolymeric Additives
Published on: May 14, 2019
Natural diamond formation by self-redox of ferromagnesian carbonate
Ming Chen1,2, Jinfu Shu3, Xiande Xie2,4
1State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640 Guangzhou, China; mchen@gig.ac.cn mao@gl.ciw.edu.
Abstract:
Formation of natural diamonds requires the reduction of carbon to its bare elemental form, and pressures (P) greater than 5 GPa to cross the graphite-diamond transition boundary. In a study of shocked ferromagnesian carbonate at the Xiuyan impact crater, we found that the impact pressure-temperature (P-T) of 25-45 GPa and 800-900 °C were sufficient to decompose ankerite Ca(Fe2+,Mg)(CO3)2 to form diamond in the absence of another reductant. The carbonate self-reduced to diamond by concurrent oxidation of Fe2+ to Fe3+ to form a high-P polymorph of magnesioferrite, MgFe3+2O4 Discovery of the subsolidus carbonate self-reduction mechanism indicates that diamonds could be ubiquitously present as a dominant host for carbon in the Earth's lower mantle.
More Related Videos
10:34Exploring the Radical Nature of a Carbon Surface by Electron Paramagnetic Resonance and a Calibrated Gas Flow
Published on: April 24, 2014
13:09Assessment of Boron Doped Diamond Electrode Quality and Application to In Situ Modification of Local pH by Water Electrolysis
Published on: January 6, 2016
Related Concept Videos
Balancing Redox Equations
Redox Reactions
Redox Reactions
Standard Enthalpy of Formation
The Carbon Cycle
Carbon Skeletons