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Crystals of karwowskiite, Ca9Mg(Fe2+0.5□0.5)(PO4)7, a new mineral of the merrillite group, were found on an amygdule wall in the central part of an anorthite–tridymite–diopside paralava of the Hatrurim Complex, Daba-Siwaqa, Jordan. The amygdule was filled with a sulfide melt, which after crystallization gave a differentiated nodule, consisting of troilite and pentlandite parts and containing tetrataenite and nickelphosphide inclusions. Karwowskiite crystals are colorless, although sometimes a greenish tint is observed. The mineral has a vitreous luster. The microhardness VHN25 is 365 (12), corresponding to 4 on the Mohs hardness scale. Cleavage is not observed, and fracture is conchoidal. The calculated density is 3.085 g/cm3. Karwowskiite is uniaxial (−): ω = 1.638 (3), ε = 1.622 (3) (λ = 589 nm), and pleochroism is not observed. The composition of karwowskiite is described by the empirical formula: Ca9.00(□0.54Fe2+0.23Mg0.12Na0.04 Sr0.03 Ni0.03K0.01) Σ1.00Mg1.00(PO4)7.02. Karwowskiite is distinct from the known minerals of the merrillite subgroup with the general formula A9XM[TO3(Ø)]7, where A = Ca, Na, Sr, and Y; X = Na, Ca, and □; M = Mg, Fe2+, Fe3+, and Mn; T = P; and Ø = O, in that the X site in it is occupied by Fe2+0.5□0.5. Karwowskiite is trigonal, space group R-3c with a = 10.3375 (2) Å, c = 37.1443 (9) Å, and V = 3437.60 (17) Å3. Karwowskiite crystallizes at temperatures lower than 1100 °C in a thin layer of secondary melt forming on the walls of amygdules and gaseous channels in paralava as a result of contact with heated gases which are by-products of the combustion process. [ABSTRACT FROM AUTHOR]

Yakubovichite, CaNi2Fe3+(PO4)3, a new mineral containing up to 20 wt% NiO, represents a novel type of terrestrial phosphate mineralization featuring an extreme enrichment in Ni. The mineral was discovered in the Hatrurim Formation (Mottled Zone)—pyrometamorphic complex whose outcrops are exposed in Israel and Jordan in the area coincident with the Dead Sea Transform fault system. Nickel-rich minerals in these assemblages also include Ni phosphides: halamishite Ni5P4, negevite NiP2, transjordanite and orishchinite—two polymorphs of Ni2P, nazarovite Ni12P5, polekhovskyite MoNiP2; Ni-spinel trevorite NiFe2O4, bunsenite NiO, and nickeliferous members of the hematite-eskolaite series, Fe2O3-Cr2O3 containing up to 2 wt% NiO. Yakubovichite forms polycrystalline segregations up to 0.2 mm in size composed of equant crystal grains, in association with crocobelonite, hematite, other phosphates, and phosphides. It has a deep yellow to lemon-yellow color, is transparent to translucent with vitreous luster, and has no cleavage. Mohs hardness = 4. Yakubovichite is orthorhombic, Imma, unit-cell parameters of the holotype material: a = 10.3878(10), b = 13.0884(10), c = 6.4794(6) Å, V = 880.94(2) Å3, Z = 4. Chemical composition of holotype material (electron microprobe, wt%): Na2O 1.82, K2O 1.76, CaO 6.37, SrO 0.49, BaO 1.37, MgO 2.13, NiO 21.39, CuO 0.16, Fe2O3 18.80, Al2O3 1.06, V2O3 0.44, Cr2O3 0.15, P2O5 44.15, total 100.09. The empirical formula calculated on the basis of 12 O atoms per formula unit is (Ca0.55Na0.29K0.18Ba0.04Sr0.02)1.08(Ni1.39Mg0.26Fe30.24+ V30.03+ Cu0.01Cr0.01)Σ1.94 (Fe30.90+ Al0.10)Σ1P3.02O12. Dcalc = 3.657 g cm–3. The strongest lines of powder XRD pattern [d(Å)(I)(hkl)]: 5.82(44)(011), 5.51(73)(101), 5.21(32)(200), 4.214(34)(121), 2.772(97)(240), 2.748(100)(202), 2.599(38)(400). Yakubovichite is the first mineral that crystallizes in the α-CrPO4 structure type. It has a direct synthetic analog, CaNi2Fe3+(PO4)3. Since yakubovichite is the first natural Ni-phosphate of non-meteoritic origin, the possible sources of Ni in the reported mineral assemblages are discussed. Pyrometamorphic rocks of the Hatrurim Formation were formed at the expense of the sediments belonging to a Cretaceous-Paleogene (Cretaceous-Tertiary) boundary (~66 Ma age). This geological frame marks the event of mass extinction of biological species on Earth that was likely caused by the Chicxulub impact event. The anomalous enrichment of pyrometamorphic assemblages in Ni may be related to metamorphic assimilation of Ni-rich minerals accumulated in the Cretaceous-Paleogene layer, which was formed due to a Chicxulub collision. [ABSTRACT FROM AUTHOR]

Crocobelonite, CaFe23+(PO4)2O, is a new natural oxyphosphate discovered in the pyrometamorphic complexes of the Hatrurim Formation in Israel and Jordan. Crocobelonite-bearing assemblages contain a series of anhydrous Fe-Ni phosphates, hematite, diopside, anorthite, and phosphides—barringerite Fe2P, transjordanite Ni2P, murashkoite FeP, halamishite Ni5P4, and negevite NiP2. Crocobelonite forms submillimeter-sized aggregates of prismatic to acicular crystals of saffron-red to pinkish-red color. There are two polymorphic modifications of the mineral whose structures are interrelated by the unit-cell twinning. Crocobelonite-2O is orthorhombic, Pnma, a = 14.2757(1), b = 6.3832(1), c = 7.3169(1) Å, V 666.76(1) Å3, Z = 4. This polymorphic modification is isotypic with synthetic oxy-phosphates A V 2 3 + P O 4 2 O where A = Ca, Sr, Cd. The crystal structure has been refined to RB = 0.71% based on powder XRD data, using the Rietveld method and the input structural model obtained from the single-crystal study. Chemical composition (electron microprobe, wt%) is: CaO 16.03, MgO 0.56, Fe2O3 43.37, Al2O3 0.33, SiO2 0.32, P2O5 39.45, Total 100.06. The empirical formula based on O = 9 apfu is C a 1.02 F e 1.94 3 + M g 0.05 A l 0.02 2.01 P 1.98 S i 0.02 2.00 O 9.00 The strongest lines of powder XRD pattern [d(Å)(I)(hkl)] are: 6.54(16)(200), 5.12(26)(201), 3.549(100)(102), 3.200(50) (401), 2.912(19)(220), 2.869(40)(411), 2.662(21)(501). Crocobelonite- 1M is monoclinic, P21/m, a = 7.2447(2), b = 6.3832(1), c = 7.3993(2) Å, β = 106.401(2)°, V = 328.252(14) Å3, Z = 2. This polymorphic modification does not have direct structural analogs. Its crystal structure has been solved and refined based on the single-crystal data to R1 = 1.81%. Chemical composition is: CaO 15.56, MgO 0.16, NiO 0.78, Fe2O3 41.28, Al2O3 0.45, V2O3 0.42, Cr2O3 0.23, TiO2 0.79, P2O5 39.94, Total 99.61, corresponding to the empirical formula (O = 9 a p f u) C a 0.99 F e 1.85 3 + N i 0.04 T i 0.04 A l 0.03 V 0.02 3 + C r 0.01 M g 0.01 2.00 P 2.01 O 9.00 with Dcalc = 3.604 g/cm3. The strongest lines of powder XRD pattern [d(Å)(I)(hkl)] are 6.98(17)(100), 4.40(22)(101), 3.547(100)(201), 3.485(21)(200), 3.195(50)(020), 2.855(38)(102), 2.389(33)(122). Crocobelonite represents a novel type of phosphate mineral formed by oxidation of phosphide minerals at temperatures higher than 1000 °C and near-atmospheric pressure (pyrolytic oxidation). [ABSTRACT FROM AUTHOR]

Iron phosphides with significant variations of Cr (up to 18 wt%) and V (up to 8.6 wt%) contents were detected in gehlenite-bearing breccia at the Hatrurim Complex, Negev desert, Israel. Investigations of the composition and structure of the Fe2P phosphides showed that when the V+Cr content is higher than 0.26 apfu (atoms per formula unit), a transition from the hexagonal barringerite (P6̅2m) to orthorhombic allabogdanite (Pnma) takes place. According to the experimental data, allabogdanite is a high-pressure (>8 GPa) polymorph of barringerite. Pseudowollastonite associated with Cr-V-bearing allabogdanite is an indicator of phosphide crystallization at high temperature (>1200 °C) and low pressure. Thus, at the low pressure close to ambient, when more than 13 at% Fe in Fe2P is substituted by Cr and V, the orthorhombic polymorph is stable. The orthorhombic phosphide with the highest Cr and V contents belongs to the andreyivanovite species with the FeCrP end-member formula. This is the first finding on Earth of that very rare mineral described from the Kaidun meteorite. Some Cr-V-bearing phosphides have an unusual morphology, which cannot be explained by crystallization from a melt. More probably, these phosphides can form in the process of replacing fish bone remains. We believe that sedimentary protolith was not thermally altered and contained a significant amount of bituminous organic matter and phosphorite inclusions. Injecting paralava into the sedimentary rocks determines the conditions for phosphide formation on the boundary of these rocks as a result of the high-temperature carbothermal reduction process. [ABSTRACT FROM AUTHOR]

The new mineral khurayyimite Ca7Zn4(Si2O7)2(OH)10·4H2O occurs in colorless spherulitic aggregates in small cavities of altered spurrite marbles located in the northern part of the Siwaqa pyrometamorphic rock area, Central Jordan. It is a low-temperature, hydrothermal mineral and is formed at a temperature lower than 100 °C. Synchrotron single-crystal X-ray diffraction experiments have revealed that khurayyimite crystallizes in space group P21/c, with unit cell parameters a = 11.2171(8), b = 9.0897(5), c = 14.0451(10) Å, β = 113.297(8)º, V = 1315.28(17) Å3 and Z = 2. The crystal structure of khurayyimite exhibits tetrahedral chains of periodicity 6. The sequence of SiO4 and ZnO2(OH)2-tetrahedra along the chain is Si–Si-Zn. The neighboring SiO4-tetrahedra of the corrugated chains are bridged by additional ZnO2(OH)2-tetrahedra to form 3-connected dreier rings. The chains can be addressed as loop-branched sechser single chains {lB, 11∞}[6Zn4Si4O21]. The chains are linked by clusters of five CaO6 and two CaO7 polyhedra with additional OH groups and H2O molecules in the coordination environment. Based on the connectedness and one-dimensional polymerisations of tetrahedra (TO4)n−, chains of khurayyimite belong to the same group as vlasovite Na2ZrSi4O11, since they can be described with geometrical repeat unit cTr = 2T43T4 and topological repeat unit cVr = 2V23V2. [ABSTRACT FROM AUTHOR]

For the first time, chromium disulphides, known from meteorites, such as caswellsilverite, NaCrS2; grokhovskyite, CuCrS2; and a potentially new mineral, AgCrS2, as well as the products of their alteration, such as schöllhornite, Na0.3CrS2∙H2O, and a potentially new mineral with the formula {Fe0.3(Ba,Ca)0.2} CrS2·0.5H2O, have been found in terrestrial rock. Layered chromium disulphides were found in unusual phosphide-bearing breccia of the pyrometamorphic Hatrurim Complex in the Negev Desert, Israel. The chromium disulphides belong to the central fragment of porous gehlenite paralava cementing altered host rock clasts. The empirical formula of caswellsilverite is (Na0.77Sr0.03Ca0.01)Σ0.81(Cr3+0.79Cr4+0.18V3+0.01 Fe3+0.01)Σ0.99S2·0.1H2O, and the end-member content of NaCrS2 is 76%. It forms single crystals in altered pyrrhotite aggregates. Grokhovskyite has the empirical formula {Cu+0.84Fe3+0.10Ca0.06 Na0.01 Sr0.01Ba0.01}Σ1.03(Cr3+0.94 Fe3+0.05 V3+0.05)Σ1.00S2·0.35H2O, and the CuCrS2 end-member content is 75–80%. A potentially new Ag-bearing chromium disulphide is characterised by the composition (Ag0.89Cu0.07)Σ0.96(Cr0.98 Fe0.03V0.01Ni0.01)Σ1.04S2. Caswellsilverite, grokhovskyite and AgCrS2 form in gehlenite paralava at high temperatures (near 1000 °C) and low pressure under reducing conditions. The structure of the layered chromium disulphides, MCrS2, is characterised by the presence of hexagonal octahedral layers (CrS2)1−, between which M-sites of the monovalent cations Ag, Cu and Na set. A low-temperature alteration of the layered chromium disulphides, when schöllhornite and {Fe0.3(Ba,Ca)0.2}CrS2·0.5H2O form, is reflected in the composition and structural modification of the layer with monovalent cations, whereas the octahedral layer (CrS2)1− remains unchanged. [ABSTRACT FROM AUTHOR]

A new mineral, gismondine-Sr with ordered gismondine framework type [B2212 no. 20, Z = 1; a = 14.0256(2) Å, b = 10.45900(10) Å, c = 13.79360(10) Å, V = 2023.44(4) Å3] and the ideal chemical formula Sr4(Si8Al8O32)·9H2O was discovered in amygdaloidal voids of partly melted gehlenite hornfels at Halamish locality, Hatrurim Basin of the Hatrurim Complex, Negev Desert, Israel. Gehlenite hornfels is mainly composed of gehlenite, wollastonite, and garnet of the grossular-andradite-schorlomite series. In a low-temperature association occur minerals such as thomsonite-Ca, flörkeite, analcime and minerals of the tobermorite supergroup. Gismondine-Sr forms spherulitic aggregates up to 180 μm and, rarely, pseudotetragonal bipyramidal crystals up to 50 μm. Empirical crystal-chemical formula of gismondine-Sr is (Sr2.02Ca1.09Ba0.02K0.72Na0.62)Σ4.47Al7.91Si8.09O31.85·9H2O. It is the strontium analog of gismondine-Ca and the second orthorhombic zeolite with the GIS structure topology. Crystals are transparent to translucent and feature vitreous luster. The mineral exhibits a white color, imperfect cleavage in [101] direction, a brittle tenacity, and uneven fracture. The Mohs hardness was estimated at approximately 4. Gismondine-Sr is biaxial negative, α = 1.488(3), β = 1.492(3), γ = 1.495(3), 2Vobs = 70–80°. The Raman spectrum is characterized by a band at 465 cm−1, which is also the main band in gismondine-Ca. The structure refinement using SC-XRD (R1 = 0.0353) reveals the ordered distribution of framework cations and the disordered arrangement of extraframework cations. The aluminosilicate framework is built by crankshaft chains with 8-membered apertures channels parallel to [101] and [101]. In gismondine-Sr, the 8-membered rings are elliptically deformed and the T-O-T angle of the upward and downward tetrahedra in the double crankshaft chains is smaller compared to that for gismondine-Ca. Consequently, a slight rotation of the double crankshaft chains has been noticed. Similar observations have been made in partially dehydrated and the pressure-modified gismondine-Ca. The present study suggests that, in addition to high-pressure and dehydration, the elliptical deformation of the channels in GIS also arises as a consequence of the extraframework cations and H2O content. Thus, the extraframework content influences the aluminosilicate framework leading to the orthorhombic symmetry. [ABSTRACT FROM AUTHOR]

Polekhovskyite, MoNiP2, is the first terrestrial Mo phosphide, a phosphorus-rich homolog of meteoritic monipite, MoNiP. The mineral represents a novel phosphide type of terrestrial Mo speciation. It was discovered among phosphide assemblages in pyrometamorphic rocks of the Hatrurim Formation (the Mottled Zone) in Israel, the area confined to the Dead Sea Transform fault system. Polekhovskyite occurs in the altered diopside microbreccia, as micrometer-sized euhedral crystals intimately intergrown with murashkoite, FeP and transjordanite, Ni2P, in association with Si-rich fluorapatite, hematite, and magnetite. In reflected light, the mineral has a bluish-gray color with no observable bireflectance and anisotropy. Chemical composition (electron microprobe, wt%): Mo 44.10, Ni 22.73, Fe 4.60, P 29.02, total 100.45, which corresponds to the empirical formula Mo0.99(Ni0.83Fe0.18)1.01P2.01 and leads to the calculated density of 6.626 g/cm. Polekhovskyite is hexagonal, space group P63/mmc, a = 3.330(1), c = 11.227(4) Å, V = 107.82(8) Å3, and Z = 2. The crystal structure has been solved and refined to R1 = 0.0431 based on 50 unique observed reflections. The occurrence of Mo-bearing phosphides at the Dead Sea Transform area is a regional-scale phenomenon, with the localities tracked across both Israel and Jordan sides of the Dead Sea. The possible sources of Mo required for the formation of Mo-bearing phosphides are herein reviewed; they are likely related to the processes of formation of the Dead Sea Transform fault system. The problem of anthropogenic contamination of geological samples with Mo and Ni is also discussed in the paper in the context of the general aspects of discrimination between natural and technogenic ultra-reduced phases. [ABSTRACT FROM AUTHOR]

Nazarovite, Ni12P5, is a new natural phosphide discovered on Earth and in meteorites. Terrestrial nazarovite originates from phosphide assemblages confined to pyrometamorphic suite of the Hatrurim Formation (the Mottled Zone), the Dead Sea basin, Negev desert, Israel. Meteoritic nazarovite was identified among Ni-rich phosphide precipitates extracted from the Marjalahti meteorite (main group pallasite). Terrestrial mineral occurs as micrometer-sized lamella intergrown with transjordanite (Ni2P). Meteoritic nazarovite forms chisel-like crystals up to 8 μm long. The mineral is tetragonal, space group I4/m. The unit-cell parameters of terrestrial and meteoritic material, respectively: a 8.640(1) and 8.6543(3), c 5.071(3), and 5.0665(2) Å, V 378.5(2), and 379.47(3) Å3, Z = 2. The crystal structure of terrestrial nazarovite was solved and refined on the basis of X‑ray single-crystal data (R1 = 0.0516), whereas the structure of meteoritic mineral was refined by the Rietveld method using an X‑ray powder diffraction profile (RB = 0.22%). The mineral is structurally similar to phosphides of schreibersite–nickelphosphide join, Fe3P-Ni3P. Chemical composition of nazarovite (terrestrial/meteoritic, electron microprobe, wt%): Ni 81.87/78.59, Fe <0.2/4.10; Co <0.2/0.07, P 18.16/17.91, total 100.03/100.67, leading to the empirical formula Ni11.97P5.03 and (Ni11.43Fe0.63Co0.01)12.07P4.94, based on 17 atoms per formula unit. Nazarovite formation in nature, both on Earth and in meteorites, is related to the processes of Fe/Ni fractionation in solid state, at temperatures below 1100 °C. [ABSTRACT FROM AUTHOR]

The new apatite-group mineral pliniusite, ideally Ca5(VO4)3F, was found in fumarole deposits at the Tolbachik volcano, Kamchatka, Russia, and in a pyrometamorphic rock of the Hatrurim Complex, Israel. Pliniusite, together with fluorapatite and svabite, forms a novel and almost continuous ternary solid-solution system characterized by wide variations of T5+ = P, As, and V. In paleo-fumarolic deposits at Mountain 1004 (Tolbachik), members of this system, including the holotype pliniusite, are associated with hematite, tenorite, diopside, andradite, kainotropite, baryte and supergene volborthite, brochantite, gypsum and opal. In sublimates of the active Arsenatnaya fumarole (Tolbachik), pliniusite–svabite–fluorapatite minerals coexist with anhydrite, diopside, hematite, berzeliite, schäferite, calciojohillerite, forsterite, enstatite, magnesioferrite, ludwigite, rhabdoborite-group fluoroborates, powellite, baryte, udinaite, arsenudinaite, paraberzeliite, and spinel. At Nahal Morag, Negev Desert, Israel, the pliniusite cotype and V-bearing fluorapatite occur in schorlomite-gehlenite paralava with rankinite, walstromite, zadovite-aradite series minerals, magnesioferrite, hematite, khesinite, barioferrite, perovskite, gurimite, baryte, tenorite, delafossite, wollastonite, and cuspidine. Pliniusite forms hexagonal prismatic crystals up to 0.3 × 0.1 mm and open-work aggregates up to 2 mm across (Mountain 1004) or grains up to 0.02 mm (Nahal Morag and Arsenatnaya fumarole). Pliniusite is transparent to semitransparent, colorless or whitish, with a vitreous luster. The calculated density is 3.402 g/cm−3. Pliniusite is optically uniaxial (–), ω = 1.763(5), ε = 1.738(5). The empirical formulas of pliniusite type specimens calculated based on 13 anions (O+F+Cl) per formula unit are (Ca4.87Na0.06Sr0.03Fe0.02)Σ4.98(V1.69As0.66P0.45S0.12Si0.09)Σ3.01 O11.97F1.03 (Mountain 1004) and (Ca4.81Sr0.12Ba0.08Na0.05)Σ5.06(V2.64P0.27S0.07Si0.03)Σ3.01O12.15F0.51Cl0.34 (Nahal Morag). Pliniusite has a hexagonal structure with space group P63/m, a = b = 9.5777(7), c = 6.9659(5) Å, V = 553.39(7) Å3, and Z = 2. The structure was solved using single-crystal (holotype) X‑ray difraction, R = 0.0254. The mineral was named in honor of the famous Roman naturalist Pliny the Elder, born Gaius Plinius Secundus (AD 23–79). It is suggested that the combination of high temperature, low pressure, and high oxygen fugacity favors the incorporation of V5+ into calcium apatite-type compounds, leading to the formation of fluorovanadates. [ABSTRACT FROM AUTHOR]