Qeltite-The first terrestrial high-Temperature mineral with a langasite-Type structure from pyrometamorphic rock of the Hatrurim Complex

Qeltite (IMA2021-032), ideally Ca3Ti(Fe₂Si)Si₂O₁₄, was found in gehlenite-rankinite-wollastonite paralava from a pyrometamorphic rock of the Hatrurim Complex at Nabi Musa locality, Judean Desert, West Bank, Palestine. It generally occurs as light-brown flattened crystals up to 40-50 μm in length and less than 5 μm in thickness. Its aggregates reach 100-200 μm in size. Its empirical crystal chemical formula based on 14 O is as follows: (Ca2.96Sr0.02Mn0.01)σ2.99Ti⁴⁺(Fe³⁺1.59Si0.60Al0.43Ti⁴⁺0.38Cr0.01)σ3.02(Si1.99P0.01)σ2O14. The strongest reflections in its calculated X-ray diffraction pattern are [d(A), I, hkl]: 3.12, 100, 111; 2.85, 61, 201; 2.85, 48, 021; 2.32, 45, 211; 6.93, 31, 100; 1.81, 30, 212. Qeltite is trigonal and it crystallizes in the noncentrosymmetric P321 space group, with a = 8.0077(5) A, c = 4.9956(4) A, V = 277.42(4) A³and Z = 1. Its microhardness VHN25 is 708(17) kg/mm², and its hardness on the Mohs scale is about 6. Its calculated density is 3.48 g/cm3. It was found in fine-grained mineral aggregates within coarse-grained main minerals of rankinite-gehlenite paralava with subordinate wollastonite, Ti-bearing andradite and kalsilite. In these aggregates, the mineral is associated with khesinite, paqueite and pseudowollastonite, indicating a high-Temperature genesis (about 1200°C). Its crystallization can be compared with the crystallization of minerals containing refractory inclusions in meteorites.