On the discovery of meteoritic mineral Zolenskyite; The artificial origin should not be overlooked

Abstract

Recently a new meteoritic mineral, Zolenskyite (Fe0.99Mn0.04Ca0.01Cr1.99S3.98), was discovered from the Indarch meteorite. Zolenskyite was structurally indexed as the monoclinic C2/m CrNb2Se4 - Cr3S4 type structure of synthetic FeCr2S4, with unit cell parameters a = 12.84(1) {\AA}, b = 3.44(1) {\AA}, c = 5.94(1) {\AA} and \b{eta} = 117(1){\deg}. Zolenskyite was reported as high-pressure phase formed from Daubr\'eelite at high pressures and temperatures in highly shocked regions of the EH parent asteroid. Although this discovery provides valuable information about the origin of meteoritic mineral assemblages, the results and conclusions raise controversies with those reported in previous articles where the synthetic FeCr2S4 was described. In this review, an alternative analysis of the supplementary X-ray data from Zolenskyite was made and yields to the monoclinic I2/m Cr3S4 type structure of synthetic FeCr2S4, with unit cell parameters a = 5.940 {\AA}, b = 3.440 {\AA}, c = 11.441 {\AA} and \b{eta} = 90.55{\deg}, in agreement with previous results in the literature and differ from those reported above. Regarding the genesis of Zolenskyite and according to solid-state laboratory synthesis, the transformation of cubic FeCr2S4 phase (ideal composition of Daubr\'eelite) to monoclinic FeCr2S4 (ideal composition of Zolenskyite) requires a process whose replication in Shock metamorphism stages is not well established and remains an open issue to address, together with another open issue related to the real composition of meteoritic minerals, with minor and trace metals, which is often overlooked when compared with synthetic ideal compositions. Whatever the results to be obtained by addressing the above open issues, they will shed more light on the genesis of Zolenskyite. In this context, it is worth to promote an open debate about the hypothesis of artificial origin.