New Mineral with Modular Structure Derived from Hatrurite from the Pyrometamorphic Rocks of the Hatrurim Complex: Ariegilatite, BaCa12(SiO4)4(PO4)2F2O, from Negev Desert, Israel

Evgeny Galuskin,Mikhail Murashko,Justyna Wojdyla,Hannes Krüger,Biljana Krüger,Yevgeny Vapnik,Irina Galuskina

doi:10.3390/min8030109

Abstract

Ariegilatite, BaCa12(SiO4)4(PO4)2F2O (R 3 ¯ m, a = 7.1551(6) Å, c = 41.303(3) Å, V = 1831.2(3) Å3, 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, (Ba0.98K0.01Na0.01)Σ1(Ca11.77Na0.08Fe2+0.06Mn2+0.05Mg0.04)Σ12(Si3.95Al0.03Ti0.02)Σ4(P1.70C0.16Si0.10S6+0.03V0.01)Σ2F2.04O0.96, 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.

Highlights

Ariegilatite, BaCa12 (SiO4 )4 (PO4 )2 F2 O (R3m, a = 7.1551(6) Å, c = 41.303(3) Å, V = 1831.2(3) Å3,Z = 3), is the first P-bearing mineral in the nabimusaite group, which combines nabimusaite, KCa12 (SiO4 )4 (SO4 )2 O2 F (R3m, a = 7.1905(4), c = 41.251(3) Å, V = 1847.1(2) Å3, Z = 3) and dargaite, BaCa12 (SiO4 )4 (SO4 )2 O3 (R3m, a = 7.1874(4); c = 41.292(3) Å; V = 1847.32(19) Å3, Z = 3) [1,2]
Minerals 2018, 8, 19 was found in altered spurrite marble belonging to the pyrometamorphic Hatrurim Complex in the
Oxygen resides in the center (Figure 3A, blue) and fluorine on the two outer octahedral sites (Figure 3A, green) of the antiperovskite module

Summary

Introduction

Minerals 2018, 8, 19 was found in altered spurrite marble belonging to the pyrometamorphic Hatrurim Complex in the. Rocks of the Hatrurim Complex mainly consist of spurrite marbles, larnite pseudoconglomerates and gehlenite hornfelses. Pyrometamorphic rocks and by-products of their low-temperature alterations commonly occur along the Dead Sea Rift in the territories of Israel, Palestine and Jordan (the “Mottled zone”) [3,4,5]. Minerals of the nabimusaite group are silicates with additional anions and are isostructural with arctite, a phosphate with an ideal crystal chemical formula of Ba(Ca7 Na5 )(PO4 ) F3 [6]. Minerals of the nabimusaite group and arctite can be described as hexagonal intercalated antiperovskites with the general crystal chemical formula AB12 (TO4 ) (TO4 ) W 3 , A = Ba, K, .

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