Midbarite, Ca ₃ Mg ₂ (V ₂ Si)O ₁₂ , a new member of the garnet supergroup from the Hatrurim Comp

A new garnet named midbarite, Ca3Mg2(V2Si)O12, has been discovered in a paralava of the pyrometamorphic Hatrurim Complex in the Hatrurim Basin near Mount Ye’elim in the Negev Desert, Israel. This paralava also contains esseneite, minerals of the levantite-latiumite series, garnet of the andradite-schorlomite series, and wollastonite as well as subordinate gehlenite, rankinite and fluorapatite. Midbarite forms overgrowths on Ti-bearing andradite or occurs as xenomotphic grains, occurring in aggregates in association with the OH-analogue of pliniusite, Ca5(VO4)3F. The size of the midbarite grains does not exceed 40 m. It is crimson red in colour, with a white streak and vitreous lustre. The Vickers hardness of 276 at a load of 10 g corresponds to a Mohs hardness of 4.5. The calculated density is 3.595 g·cm-3. Midbarite crystallises in the cubic system (Ia-3d space group), with a unit cell parameter of a = 12.3539(4) Å. The empirical formula of the holotype garnet grain is (Ca2.99Na0.05)Σ3.04(Mg0.79Mn2+ 0.65Mn3+ 0.24Fe3+ 0.17Ti4+ 0.10Nb5+ 0.02)Σ1.97 (V5+ 1.54 Si1.29Fe3+ 0.15 Al0.01)Σ2.99O12. There is only one strong band in the Raman spectrum of midbarite at 824 cm-1, which is related to (VO4)3- vibrations. Midbarite is an accessory mineral in the paralava, and its paragenesis indicates that it formed in the sanidinite facies under increased pressure. Midbarite, as well as the OH analogue of pliniusite, and the V-bearing latiumite and https://doi.org/10.1180/mgm.2026.10202 Published online by Cambridge University Press 2 fluorapatite crystallised from small portions of melt residue between early-forming rock- forming minerals, which became locally enriched in V. А synthetic phase with the composition Ca3Mg2SiV2O12 has been synthesised at a temperature of 1250C, confirming our hypothesis that midbarite has a high-temperature genesis. Midbarite is the first member of a new group with a Z-site charge of 14 in the garnet supergroup. Key words: new mineral ; midbarite; silicate-vanadate garnet; garnet supergroup; structure; Raman; paralava; Hatrurim Complex; Israel