¹Chi Ma,²Oliver Tschauner,³John G. Spray,⁴Zhongxu Pan
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.70129]
¹Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA
²Department of Geoscience, University of Nevada, Las Vegas, Nevada, USA
³Planetary and Space Science Centre, University of New Brunswick, Fredericton, New Brunswick, Canada
⁴School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui, China
Published by arrangement with John Wiley & Sons

We report a previously unknown aluminosilicate mineral, (Si0.91□0.09)Σ1.00(Al1.46□0.54)Σ2.00O4 with a vacancy-stabilized spinel-type structure (henceforth “SiAl-spinel”). This novel aluminosilicate occurs with coesite, stishovite, and majoritic garnet in a shock melt vein in metaquartzite from the outer collar of the Vredefort Dome, the eroded central uplift of the Vredefort impact structure of South Africa. Formation conditions for this new high-pressure, high-temperature phase are around 10 GPa and 1400°C, upon release from peak shock conditions. Based on its composition and formation conditions, this new high-pressure, high-temperature phase is predicted to be a common occurrence in terrestrial impactites and in subducted slabs.