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Ariegilatite, BaCa₁₂(SiO₄)₄(PO₄)₂F₂O (R $\overline{3}$ m, a = 7.1551(6) Å, c = 41.303(3) Å, V = 1831.2(3) ų, Z = 3), is a new member of the nabimusaite group exhibiting a modular intercalated antiperovskite structure derived from hatrurite. It was found in a few outcrops of pyrometamorphic rocks of the Hatrurim Complex located in the territories of Israel, Palestine and Jordan. The holotype specimen is an altered spurrite marble from the Negev Desert near Arad city, Israel. Ariegilatite is associated with spurrite, calcite, brownmillerite, shulamitite, CO₃-bearing fluorapatite, fluormayenite-fluorkyuygenite and a potentially new mineral, Ba₂Ca₁₈(SiO₄)₆(PO₄)₃(CO₃)F₃O. Ariegilatite is overgrown and partially replaced by stracherite, BaCa₆(SiO₄)₂[(PO₄)(CO₃)]F. The mineral forms flat disc-shaped crystals up to 0.5 mm in size. It is colorless, transparent, with white steaks and vitreous luster. Optically, ariegilatite is uniaxial, negative: ω = 1.650(2), ε = 1.647(2) (λ = 589 nm). The mean composition of the holotype ariegilatite, (Ba_0.98K_0.01Na_0.01)_Σ1(Ca_11.77Na_0.08Fe²⁺_0.06Mn²⁺_0.05Mg_0.04)_Σ12(Si_3.95Al_0.03Ti_0.02)_Σ4(P_1.70C_0.16Si_0.10S⁶⁺_0.03V_0.01)_Σ2F_2.04O_0.96, is close to the end-member formula. The structure of ariegilatite is described as a stacking of the two modules {F₂OCa₁₂(SiO₄)₄}⁴⁺ and {Ba(PO₄)₂}⁴⁻ along (001). Ariegilatite, as well as associated stracherite, are high-temperature alteration products of minerals of an early clinker-like association. These alterations took place under the influence of pyrometamorphism by-products, such as gases and fluids generated by closely-spaced combustion foci. Full article