New minerals with a modular structure derived from hatrurite from the pyrometamorphic Hatrurim Complex. Part II. Zadovite, BaCa₆[(SiO₄)(PO₄)](PO₄)₂F and aradite, BaCa₆[(SiO₄)(VO₄)](VO₄)₂F, from paralavas of the Hatrurim Basin, Negev Desert, Israel

Abstract

Zadovite, BaCa6[(SiO4)(PO4)](PO4)2F (R3m, a = 7.0966(1) Å, c = 25.7284(3), V = 1122.13(3) Å3, Z = 3) and aradite, BaCa6[(SiO4)(VO4)] (VO4)2F (R3m, a = 7.1300(1), c = 26.2033(9) Å, V = 1153.63(6) Å3, Z = 3) are two new mineral species of a novel modular structure type related closely to the structure of nabimusaite, KCa12(SiO4)4(SO4)2O2F. Both minerals occur in paralavas enclosed in pyrometamorphic rocks of the Hatrurim Complex, Negev desert, Israel. Zadovite and aradite are colourless, transparent with a white streak, have a vitreous lustre and an uneven fracture. Both minerals are uniaxial (–) with refractive indices (589 nm) ω = 1.711(2), ε = 1.708(2) (zadovite) and ω = 1.784(3), ε = 1.780(3) (aradite). The zadovite structure type comprises two tetrahedral sites, which may host a broad compositional range of atoms such as Si, P, V and S. Results of electron microprobe analyses show a correlation between excess Si4+ and S6+ contents, suggesting the substitution scheme 2(P,V)5+ = Si4+ + S6+ at the tetrahedral sites. This points to the possibility of new minerals isostructural with zadovite with end-member formulae BaCa6(SiO4)2[(PO4)(SO4)]F, BaCa6(SiO4)2[(VO4)(SO4)]F, BaCa6[(SiO4)1.5(SO4)0.5](PO4)2F and BaCa6[(SiO4)1.5(SO4)0.5](VO4)2F. The Raman spectra of aradite and zadovite reflect the varying PO4 (e.g. change of band intensity at ∼1031 cm–1) and VO4 contents (e.g. change of band intensity at ∼835 cm–1). The presence of SO4 leads to an additional Raman band at ∼997 cm–1. The structure of zadovite-series minerals belonging to the nabimusaite group is characterized by a 1:1 alternation of antiperovskite-like {[FCa6](TO4)2}4+ modules and Ba(TO4)2–4 modules.

Mineralogical Diversity of Ca2SiO4-Bearing Combustion Metamorphic Rocks in the Hatrurim Basin: Implications for Storage and Partitioning of Elements in Oil Shale Clinkering

“…Rock-forming minerals of Ca-rich paralavas are gehlenite, Ca 3 Si 3 O 9 and Ca 2 SiO 4 modifications, rankinite, Ti-rich andradite, kalsilite, fluorapatite-fluorellestadite solid solutions. Their accessory assemblages are highly variable and a lot of rare and new minerals came from this rock type [1, 24,32,52,55,59].…”

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

“…Minerals of the zadovite group can also be described as intercalated antiperovskites. Their general formula is AB 6 (TO 4 [7,9]. In stracherite, about half of the (PO 4 ) 3− tetrahedra are replaced by (CO 3 ) 2− groups [10].…”

Se–Cl Interactions in Selenite Chlorides: A Theoretical Study

“…This approach was first proposed in 1968 [56] and recently developed into a coherent crystal chemical theory (see [57,58] for reviews and historical remarks). In general, description of certain crystal structures in terms of anion-centered coordination polyhedra became more popular over the years, in part due to the recent reports on interesting structural and physical properties and mineralogical importance of antiperovskites, i.e., materials with structures based upon anion-centered octahedra [59][60][61][62][63][64][65][66].…”

“…The complex 1-dimensional structural units with the composition {[O 2 Cu 5 ](SeO 3 ) 2 } 2+ shown in Figure 4b are the basic structural modules for both polymorphs and it is the mode of their combination that generates the structural difference. interesting structural and physical properties and mineralogical importance of antiperovskites, i.e., materials with structures based upon anion-centered octahedra [59][60][61][62][63][64][65][66].…”