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The laterite Ni ore smelting operations at Vozarci, North Macedonia, which produces ferronickel since 1982, have produced large amounts of smelting wastes dumped at the smelter. In May 2022 we have sampled three different types of slags occurring in these slag dumps. Slag 1 was produced using predominantly ore imported from Indonesia, slag 2 was formed using the ore from the nearby Ržanovo mine and slag 3 was produced using predominantly ore imported from the Ivory Coast. X-ray fluorescence (XRF) spectroscopy analyses showed that slags 1 and 3 contain between 43–47 wt.% SiO2 and slag 2 35 wt.% SiO2. Relative to slags 1 and 3, slag 2 is enriched in iron (40 wt.% Fe2O3). Furthermore, slag 2 is characterized by a large Cr content (ca. 17400 ppm of Cr2O3). A combination of powder X-ray diffraction, Raman spectroscopy and SEM-EDS analyses (of polished aliquots) showed that the slags consist of silicate glass, synthetic equivalents of orthopyroxenes (enstatite), clinopyroxenes (clinopyroxene, diopside, pigeonite, augite), olivines (forsterite, fayalite) and subordinate spinel-group phases (chromite, magnesiochromite, magnetite, trevorite), sulphides (pyrrhotite and FeS-NiS phases) and intermetallic compounds (metallic Fe with up to 10 at.% Ni and remnants of ferronickel). All three slags contain significant amounts of the following potentially toxic elements: Co (20-87 ppm), Cr (9600-17400 ppm), Ni (500-730 ppm) and Zn (150-380 ppm). The phase assemblages and textures in the Vozarci slags are similar to those in other pyrometallurgical slags produced during reworking of silicate and sulphide ores. Although the slags 1 and 2 have been exposed to atmospheric conditions for about 40 years, those occurring in the dumps are not much affected by weathering. At present, we have identified the following alteration products: (i) abundant iron oxy-hydroxides (including lepidocrocite) (slag 1), (ii) minor nesquehonite, MgCO3·3H2O (slag 2) and (iii) syngenite, K2Ca(SO4)2·H2O (slag 1). Since slag 3 is newly deposited slag, it is not weathered at all.Financial support of the Federal Ministry of Education, Science and Research (BMBWF) and Austria´s Agency for Education and Internationalisation (OeAD), (WTZ Grant MK 06/2022) is gratefully acknowledged.

Saccoite, Ca2Mn3+2F(OH)8⋅0.5(SO4), is a new mineral found at the N'Chwaning III mine, Kalahari Manganese Field, Northern Cape Province, Republic of South Africa. It occurs as fillings of voids in hydrothermally altered manganese ore (comprising mostly of bixbyite and baryte). Further associated minor minerals are braunite, gypsum, chlorite, sturmanite and ettringite. Saccoite forms small needles, felted crystal masses or crusts. The new mineral is olive green, transparent, with white streak and vitreous lustre. No luminescence is observed. Saccoite is uniaxial (–) with refractive indices at 589(1) nm of ω = 1.705(5) and ɛ = 1.684(2). Pleochroism is distinct, i.e. bluish green (ω) and yellowish green (ɛ). The chemical composition was studied by means of an electron probe micro-analyser (EPMA) using wavelength-dispersive X-ray spectrometry (WDS). The empirical mineral formula is Ca2.06Mn3+1.78Cu0.10Mg0.07F0.97(OH)8.02(SO4)0.39. The unit-cell dimensions of saccoite (space group P4/ncc) are a = 12.834(3) Å, c = 5.622(2) Å, V = 926.0(4) Å3), and the calculated mass density is 2.73 g⋅cm–3. Saccoite exhibits a heteropolyhedral framework structure that is composed of edge- and corner sharing CaF2(OH)6 and M(OH)6 polyhedra (M = Mn3+ and Cu2+) with large channels along [001], which host disordered and only partially occupied groups, especially SO42–. The hydrogen atoms of the OH groups point into the channel to form hydrogen bonds with the channel anions. Ca–F distances are ~2.3 Å, the Ca–OH distances in the range of 2.44–2.58 Ǻ, and the M(OH)6 octahedron is strongly 4+2 Jahn-Teller distorted (4 × ~1.92 Å, 2 × 2.27 Å). The F atom is tetrahedrally coordinated to calcium atoms. The strongest lines in the powder X-ray diffraction pattern [d in Å (relative intensity) (hkl)] are: 9.0735 (35) (110), 4.5370 (95) (220), 4.0644 (20) (310), 3.0105 (100) (321), 2.8117 (20) (002), 2.7242 (75) (411), 1.9755 (35) (611), and 1.8142 (20) (550).

Philipsburgite has been redefined as the intermediate member of the goldhillite–philipsburgite–kipushite isomorphous series with the ideal formula Cu5Zn[(AsO4)(PO4)](OH)6⋅H2O due to the site-selective As–P substitution. The new mineral goldhillite, ideally Cu5Zn(AsO4)2(OH)6⋅H2O [or Cu5Zn(AsO4)(AsO4)(OH)6⋅H2O], is the arsenate end-member of this series. Goldhillite occurs on fracture surfaces in a rock comprised mostly of quartz with iron hydroxides in association with mixite, cornwallite and conichalcite. Goldhillite forms transparent, bright emerald-green, tabular crystals with vitreous lustre, flattened on {100}, up to 1 mm across and in rosettes up to 1.5 mm. The mineral is brittle with uneven fracture and perfect cleavage on {100}; the Mohs hardness is 3.5. The calculated density for the holotype is 4.199 g cm–3. The Raman spectrum is consistent with the presence of H2O-molecules, OH-groups, AsO4 tetrahedra and traces of PO4. Electron microprobe analyses of goldhillite (H2O content based on the crystal structure) provided: CuO 48.91, ZnO 13.18, As2O5 26.06, P2O5 3.25, H2O 8.97, total 100.37 wt.%. The empirical formula for goldhillite based on O = 15 apfu is (Cu4.69Zn1.23)Σ5.92(As0.86P0.18O4)2(OH)5.61⋅H2O. The crystal structures of goldhillite and philipsburgite were determined using single-crystal X-ray diffraction data and refined to R1 = 0.054 (for 2365 I > 2σI reflections) and 0.052 (for 2308 I > 2σI reflections), respectively. Goldhillite is monoclinic, P21/c, a = 12.3573(5), b = 9.2325(3), c = 10.7163(4) Å, β = 97.346(4)°, V = 1212.59(8) Å3 and Z = 4. Philipsburgite is monoclinic, P21/c, a = 12.3095(9), b = 9.2276(3), c = 10.7195(3) Å, β = 97.137(7)°, V = 1208.16(10) Å3 and Z = 4. The strongest lines of the powder X-ray diffraction pattern of goldhillite [d, Å (I, %)(hkl)] are: 4.09 (28)(300), 3.41 (23)(12$\bar{2}$, 221, 311), 2.57 (100)(132, 11$\bar{4}$, 20$\bar{4}$), 2.17 (18)(42$\bar{3}$, 332), 1.95 (22)(432) and 1.54 (20)(13$\bar{6}$, 060). Goldhillite is named after its type locality, the Gold Hill mine, Tooele County, Utah, USA.

Alumino-oxy-rossmanite, ideally ☐Al3Al6(Si5AlO18)(BO3)3(OH)3O, is here described as a new member of the tourmaline supergroup. It is an early magmatic Al-rich oxy-tourmaline from a small pegmatitic body embedded in amphibolite and biotite-rich paragneiss. This new pink tourmaline was found in a Moldanubian pegmatite (of the Drosendorf Unit) that occurs in a large quarry near the village of Eibenstein an der Thaya, Waidhofen an der Thaya district, Lower Austria, Austria. The empirical formula of the holotype was determined on the basis of electron microprobe analysis (EMPA), secondary ion mass spectrometry (SIMS), spectroscopical methods (optical absorption and infrared spectroscopy), and crystal-structure refinement (SREF) as X(☐0.53Na0.46Ca0.01) Y(Al2.37Mn0.213+Li0.16☐0.14Mn0.072+Fe0.033+Fe0.012+Ti0.014+) ZAl6(Si5.37Al0.41B0.22O18)(BO3)3V[(OH)2.77O0.23] W[O0.80(OH)0.15F0.05]. Chemical composition (wt%) is: SiO2 33.96, TiO2 0.10, Al2O3 47.08, B2O3 11.77, FeO 0.08, Fe2O3 0.23, MnO 0.52, Mn2O3 1.70, CaO 0.04, Li2O 0.25, ZnO 0.03, Na2O 1.51, H2O 2.79, F 0.09, total 100.11. The presence of relatively high amounts of trivalent Mn in alumino-oxy-rossmanite is in agreement with the observation that the OH groups are present at a lower concentration than commonly found in other Al-rich and Li-bearing tourmalines. The crystal structure of alumino-oxy-rossmanite [space group R3m; a = 15.803(1), c = 7.088(1) Å; V = 1532.9(3) Å3] was refined to an R1(F) value of 1.68%. The eight strongest X-ray diffraction lines in the (calculated) powder pattern [d in Å (I) hkl] are: 2.5534 (100) 051, 3.9508 (85) 220, 2.9236 (78) 122, 4.1783 (61) 211, 2.4307 (55) 012, 2.0198 (39) 152, 1.8995 (30) 342, 6.294 (28) 101. The most common associated minerals are quartz, albite, microcline, and apatite. Beryl and, in places, schorl are also found as primary pegmatitic phases. Because of the low mode of associated mica (muscovite), we assume that the silica melt, which formed this pegmatite, crystallized under relatively dry conditions, in agreement with the observation that alumino-oxy-rossmanite contains a lower amount of OH than most other tourmalines. This new member of the tourmaline supergroup exhibits the most Al-rich end-member composition of the tourmaline supergroup (theoretical content: ~54 wt% Al2O3). The significant content of tetrahedrally coordinated Al could reflect the relatively high-temperature conditions (~700 °C) inferred for crystallization of the pegmatite. Alumino-oxy-rossmanite was named for its chemical relationship to rossmanite, ☐(LiAl2)Al6(Si6O18) (BO3)3(OH)3(OH), which in turn was named after George R. Rossman, Professor of Mineralogy at the California Institute of Technology (Pasadena, California, U.S.A.).

Katsarosite, ideally Zn(C2O4)·2H2O, named for Īraklīs Katsaros, is a new mineral found at the Esperanza Mine in the Kaminiza area of the Lavrion Mining District, Greece. Katsarosite usually occurs directly on sphalerite or embedded in jarosite and/or hydrozincite, often intimately intergrown with gypsum and overgrown by goslarite and/or epsomite. Crystal aggregates are mostly fine granular to earthy, with individual crystals being usually rounded with an average diameter of 30 µm, sometimes prismatic along [001] or platy, exhibiting the indistinct forms {100}, {001}, {110}, and {101}. Katsarosite is malleable with a Mohs hardness of 1½ – 2 and exhibits a perfect cleavage on {110}; the fracture is uneven in all other directions. The colour depends on the iron (Fe2+) content, ranging from pure white in almost Fe-free samples to yellow in Fe-rich specimens. It has a resinous luster and a white streak; no luminescence has been observed under either short- or long-wave ultraviolet radiation. Katsarosite is optically biaxial (+). Refractive indices measured at a wavelength of 589 nm are nα = 1.488(2), nβ = 1.550(2), nγ = 1.684(2), with 2Vobs = 71(3)°. Chemical analysis gave on average C2O3 38.32 wt%, ZnO 38.99 wt%, FeO 1.92 wt%, and H2O 19.04 wt% (the latter was deduced based on the crystal-structure refinement), with traces of MgO and MnO. The new mineral is readily soluble in dilute acids. Katsarosite is monoclinic, space group C2/c, with unit-cell parameters a = 11.768(3), b = 5.3882(12), c = 9.804(2) Å, β = 127.045(8)°, V = 496.2(2) Å3 (Z = 4). The strongest lines in the Gandolfi X-ray powder pattern [dobs in Å, Iobs/I100, (hkl)] are: 4.6745, 100, (200); 4.7678, 94, (20$$\overline{2 }$$ 2 ¯ ); 2.9533, 51, (40$$\overline{2 }$$ 2 ¯ ); 4.7030, 37, (1 $$\overline{1 }\,\overline{1 }$$ 1 ¯ 1 ¯ ); 3.9266, 33, (002); 3.5686, 27, (111); 2.6574, 22, (1 $$\overline{1 }\,\overline{3 }$$ 1 ¯ 3 ¯ ); 3.5992, 8, (1 $$\overline{1 }\,\overline{2 }$$ 1 ¯ 2 ¯ ); 2.7032, 4, (020). The crystal structure was refined based on single-crystal X-ray diffraction data to R(F) = 0.08. The observed mass density of 2.50(2) g cm−3 compares well with the calculated value (2.508 g cm−3). Katsarosite belongs to the humboldtine group, whose crystal-structure type is well described for both isotypic minerals and synthetic compounds in the literature. The atomic arrangement in Zn(C2O4)·2H2O is characterized by chains consisting of isolated ZnO6 octahedra which are alternately linked along [010] via oxalate anions. These chains are interconnected through hydrogen bonds only, with Ow···O (with Ow denoting the O atom of the H2O molecule) donor–acceptor distances of ~ 2.8 Å.

The investigation of the presence and role of sulfates in our solar system receives growing attention because these compounds play a crucial role in the water budget of planets such as Mars and significantly influence melting equilibria on the icy moons of Saturn and Jupiter, leading to the formation of subsurface oceans and even cryovolcanism. Despite the dominant presence of higher sulfate hydrates such as epsomite, MgSO4·7H2O, and mirabilite, Na2SO4·10H2O, on these moons' surfaces, it is not excluded that lower-hydrated sulfates, such as kieserite, MgSO4·H2O, are also present, forming from higher hydrates under pressures relevant to the mantle of the icy moons. Given the composition of the soluble fraction in C1 and C2 chondritic meteorites, which are high in Ni content and also considered to represent the composition of the rocky cores of the Jovian icy moons, the actual compositions of potentially present monohydrate sulfates likely lie at intermediate values along the solid-solution series between kieserite and transition-metal kieserite-group end-members, incorporating Ni in particular. Moderate Ni contents are also probable in kieserite on Mars due to the planet's long-term accumulation of meteoritic nickel, although likely to a much lesser extent than Fe. Structural and spectroscopic differences between the pure Mg- and Ni-end-members have been previously documented in the literature, but no detailed crystal chemical and spectroscopic investigation along the Mg-Ni solid solution has been done yet. The present work proves the existence of a continuous (Mg,Ni)SO4·H2O solid-solution series for the first time. It provides a detailed insight into the changes in lattice parameters, structural details, and positions of prominent bands in infrared (transmission, attenuated total reflectance, diffuse reflectance) and Raman spectra in synthetic samples as the Ni/Mg ratio progresses, at both ambient as well as low temperatures relevant for the icy moons and Mars. UV-Vis-NIR crystal field spectra of the Ni end-member also help to elucidate the influence of Ni2+-related bands on the overtone- and combination modes. The (Mg,Ni)SO4·H2O solid-solution series shows Vegard-type behavior, i.e., lattice parameters as well as spectral band positions, change along linear trends with increasing Ni content. Infrared spectra reveal significant changes in the wavenumber positions of prominent bands, depending on the Ni/Mg ratio. We show that the temperature during measurement also has an influence on band position, mainly in the case of H2O-related bands. The changes observed for several absorption features in the IR spectra enable rough estimation of the Ni/Mg ratio in the monohydrate sulfate, which is applicable to present and future remote sensing data, as well as in situ measurements on Mars or the icy moons. The spectral features most diagnostic of composition are the vibrational stretching modes of the H2O molecule and a band unique to kieserite-group compounds at around 900 cm–1 in the IR spectra, as well as the pronounced ν3 and ν1 sulfate stretching modes visible in Raman spectra.

Stergiouite is a new mineral from the Plaka area in the northern part of the Lavrion Mining District, Greece. The mineral occurs as clusters of stacked, platy crystals, associated with galena, sphalerite, native arsenic and sulfur. The crystals are white to colorless, with a pearly luster and white streak. No luminescence under ultraviolet (UV) radiation is observed. Stergiouite is brittle and has a Mohs hardness of ~3. Chemical analysis gave As2O5 42.93 wt%; Sb2O5 2.45 wt%; CaO 10.90 wt%; ZnO 29.79 wt%; and H2Ocalc 13.93 wt%, which corresponds to an empirical formula Ca1.02Zn1.91((As0.95Sb0.08)O4)Σ2.03 · 4H2O. The ideal formula is CaZn2(AsO4)2 · 4H2O. Stergiouite is monoclinic, space group Pc, with unit-cell parameters a 9.416(2) A; b 5.300(1) A; c 10.893(2) A; β 91.767(10)°; V 543.36(3) A3; Z = 2. The strongest lines in the Gandolfi X-ray powder pattern [d in A, I/I100, (hkl)] are: 9.406, 100, (100); 4.619, 80, (102), (110); 3.612, 35, (20 $$ \overline{2} $$ ); 3.494, 35, (112); 2.984, 60, (21 $$ \overline{2} $$ ); 2.922, 50, (212); 2.720, 20, (004); and 2.647, 25, (020). The crystal structure was refined based on single-crystal X-ray diffraction data to R1 = 0.046, wR2 = 0.093. The observed mass density of 3.1(2) g cm−3 compares well with the calculated value (3.183 g cm−3). The framework structure of stergiouite is built up by one type of CaO2(H2O)4 octahedron and each two ZnO4 and AsO4 tetrahedra. These polyhedra share common corners to form three- and four-membered rings. A system of hydrogen bonds (O–O range: 2.70–3.02 A) further stabilizes the structure. The crystal structure of stergiouite is closely related to that of phosphophyllite [Fe[6]Zn2[4](PO4)2 · 4H2O] as well as with members of the hopeite [Zn[6]Zn2[4](PO4)2 · 4H2O] group. Stergiouite is named in honour of Vasilis Stergiou (born 1958) in recognition of his contributions to the mineralogy of the Lavrion deposits.

Hematite nanoparticles possess unique properties which have motivated substantial attention for numerous applications, including environmental remediation and wastewater treatment as a promising novel technology. The magnetite-silicate raw material of Kiruna-type ore has been introduced as an innovative precursor, decreasing the attrition balance limit for large-scale production of the ball-mill-derived hematite nanoparticles below the critical size. In this study, the hypothesis and the postulated role of quartz in the effective size reduction process were further investigated. The prepared samples were characterized in detail via X-ray fluorescence (XRF) and powder X-ray diffractometry (pXRD) to be compared with the previous results. Furthermore, the catalytic and photocatalytic activities of the obtained nanoparticles were evaluated in the oxidation reaction of a common persistent sulfo-organic contaminant. The results exposed outstanding reactivity, particularly in their photocatalytic performance, suggesting them as a strong oxidizing agent and active photocatalyst, which greatly promises many possible applications including water and environmental remediation.

The influence of temperature on the early hydration of belite-calcium sulfoaluminate cements with two different calcium sulfate to calcium sulfoaluminate molar ratios was investigated. The phase composition and phase assemblage development of cements prepared using molar ratios of 1 and 2.5 were studied at 25, 40 and 60 °C by in situ X-ray powder diffraction. The Rietveld refinement method was used for quantification. The degree of hydration after 24 h was highest at ambient temperatures, but early hydration was significantly accelerated at elevated temperatures. These differences were more noticeable when we increased the temperature from 25 °C to 40 °C, than it was increased from 40 °C to 60 °C. The amount of calcium sulfate added controls the amount of the precipitated ettringite, namely, the amount of ettringite increased in the cement with a higher molar ratio. The results showed that temperature also affects full width at half maximum of ettringite peaks, which indicates a decrease in crystallite size of ettringite at elevated temperatures due to faster precipitation of ettringite. When using a calcium sulfate to calcium sulfoaluminate molar ratio of 1, higher d-values of ettringite peaks were observed at elevated temperatures, suggesting that more ions were released from the cement clinker at elevated temperatures, allowing a higher ion uptake in the ettringite structure. At a molar ratio of 2.5, less clinker is available in the cement, therefore these differences were not observed.

The abstract is available here: https://uscholar.univie.ac.at/o:1504470

The wide range of actual and potential applications of nanoparticles, highlight the necessity of a reliable production method for both quality and quantity of the products. Mechanical attrition is one of the first well-known techniques used to produce nanoparticles. However, these approaches have been restricted to produce uniform particles below the critical size of 15 nm because of the attrition balance limit. This paper introduces the magnetite–silicate raw material of a Kiruna-type ore deposit as a novel precursor, which enables the production of small iron oxide nanoparticles below the critical size by mechanical attrition. X-ray fluorescence (XRF), powder X-ray diffractometry (pXRD), dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used for characterization of the precursor and obtained nanoparticles. The results indicate that the particles with a mean diameter of 10.7(2.7) nm consist of mainly less than one crystallite. The significant size reduction below the attrition balance limit can be attributed to the quartz content of the raw material, which operated as supporting micro-balls for transferring the energy during the milling process.

Voudourisite, Cd(SO4)·H2O, and lazaridisite, Cd3(SO4)3·8H2O, are two new minerals from the Esperanza Mine, Kaminiza Area, Lavrion Mining District, Greece. This small ancient mine is also the type locality of niedermayrite and katerinopoulosite. Further associated minerals are sphalerite, galena, edwardsite, chalcanthite, gypsum and greenockite. Both secondary minerals form tiny clusters or crusts and are among the latest to form in this paragenetic sequence. They are colourless or white, transparent to translucent, with a white streak and vitreous lustre. No fluorescence is observed. The minerals exhibit conchoidal fracture, no cleavage or preferred parting. The Mohs hardness is ~3 and both have brittle tenacity. Voudourisite is biaxial (–) with refractive indices at 589(1) nm of α = 1.580(2), β = 1.624(2), γ = 1.640(2), 2Vmeas.= 70(5)°, 2Vcalc.= 61° and β ~ || [010]. Lazaridisite is biaxial neutral with refractive indices at 589(1) nm of α = 1.552(2), β = 1.561(2), γ = 1.570(2), 2Vmeas.= 90(5)° and 2Vcalc.= 90°. The chemical compositions of voudourisite and lazaridisite are close to ideal with only minor amounts of copper detectable. The atomic arrangement in voudourisite (space groupP21/cwitha= 7.633(2),b= 7.458(2),c= 8.151(2) Å, β = 122.35(1)° andV= 392.0(2) Å3) is related to that of kieserite while lazaridisite (space groupC2/cwitha= 14.813(3),b= 11.902(2),c= 9.466(2) Å, β = 97.38(1)° andV= 1655.2(6) Å3) is a distinct structure-type. Calculated densities are 3.838 and 3.088 g/cm3, respectively.The strongest lines in the powder X-ray pattern [din Å (I) (hkl)] are: 4.890 (66) (110); 3.741 (25) (020); 3.578 (100) (11$\bar 2$); 3.230 (43) (200); 2.525 (33) (022); 2.395 (29) (112) for voudourisite and 6.860 (100) (200); 6.317 (72) (111); 5.965 (84) (020); 4.512 (58) (310); 3.727 (78) (202); 3.608(82)(13$\bar 1$); 3.109 (83) (40$\bar 2$); 3.020 (50) (33$\bar 1$) for lazaridisite, respectively.

Biochar is a promising immobilization tool for various contaminants in liquid wastes, aqueous solutions and soils. To further improve the sorption characteristics, a biochar/montmorillonite composite was produced and synthesized in an experimental pyrolysis reactor, using bamboo as biomass feedstock. The composite was characterized by physico-chemical and structural methods (FTIR, SEM, SEM/EDX, SSA, Low temperature nitrogen adsorption method). Based on these methods, the successful preparation of a bamboo based biochar/montmorillonite composite preparation has been demonstrated. The particles of montmorillonite were distributed across the biochar surface. The adsorption studies for removal nitrates from aqueous solutions were investigated by a batch method at laboratory temperatures. The experimental data were fitted by three adsorption models (Langmuir, Freundlich and DR; R2 > 0.93). The maximum adsorption capacity achieved by biochar at pH 4, was about 5 mg g−1 and by biochar/montmorillonite composite 9 mg g−1. The results suggest that the bamboo-based biochar/montmorillonite composite can be used effectively in the treatment of industrial effluents or waste water containing anionic pollutants such as nitrates.

Bosiite, NaFe3+3(Al4Mg2)(Si6O18)(BO3)3(OH)3O, is a new mineral species of the tourmaline supergroup from the Darasun gold deposit (Darasun mine), Vershino-Darasunskiy, Transbaikal Krai, Eastern-Siberian Region, Russia (52°20′24″N, 115°29′23″E). Bosiite formed as a hydrothermal phase in a gold-bearing quartz-vein spatially related to the Amudzhikan–Sretensky subvolcanic K-rich granodiorite-porphyry intrusion. Ores of this deposit are enriched in sulfides (up to 60%). Bosiite is intimately associated with other tourmalines. The first tourmaline generation is bosiite, which is followed by a second generation of oxy-dravite and a third generation of dravite. Bosiite also coexists with quartz and pyrite; further associated minerals in the vein are gangue minerals (quartz, calcite, and dolomite), sulfides (pyrite, arsenopyrite, chalcopyrite, pyrrhotite, tetrahedrite, sphalerite, and galena) and native gold. Crystals of bosiite are dark brown to black with a pale-brown streak. Bosiite is brittle and has a Mohs hardness of 7; it is non-fluorescent, has no observable parting and cleavage. It has a measured density of 3.23(3) g/cm3 (by pycnometry) and a calculated density of 3.26(1) g/cm3. In plane-polarized light, it is pleochroic, O = yellow-brown, E = red-brown. Bosiite is uniaxial negative, ω = 1.760(5), ϵ = 1.687(5). The mineral is trigonal, space group R 3 m , a = 16.101(3), c = 7.327(2) A, V = 1645.0(6) A3. The eight strongest X-ray diffraction lines in the (calculated) powder pattern [ d in A( I ) hkl ] are: 2.606(100)(50-1), 8.051(58)(100), 3.008(58)(3-1-2), 4.025(57)(4-20), 3.543(50)(10-2), 4.279(46) (3-11), 2.068(45)(6-1-2), 4.648(28)(300). Analysis by a combination of electron microprobe (EMPA), inductively coupled plasma mass spectrometry (ICP-MS), Mossbauer spectroscopic data and crystal-structure refinement results in the empirical structural formula: ![Formula][1] According to the IMA-CNMNC guidelines, the dominant valence at the Y site is 3+ and the dominant cation is Fe3+. To accommodate the disorder and allocating cations to the Z and Y sites, the recommended procedure leads to the optimized empirical formula (based on 31 O): X (Na0.73Ca0.23□0.04) Y (Fe3+2.40Fe2+0.59Ti4+0.01) Z (Al3.36Mg1.69Fe3+0.95) T (Si5.92Al0.08O18) (BO3)3 V (OH)3 W [O0.85(OH)0.15]. Bosiite, ideally NaFe3+3(Al4Mg2)(Si6O18)(BO3)3(OH)3O, is related to end-member povondraite, ideally NaFe3+3(Fe3+4Mg2)(Si6O18)(BO3)3(OH)3O, by the substitution Z Al4 → Z Fe3+4. Further, bosiite is related to oxy-dravite, ideally Na(Al2Mg)(Al5Mg)(Si6O18)(BO3)3(OH)3O, by the substitutions [6]Fe3+3 → [6]Al3. Bosiite is named after Dr. Ferdinando Bosi, researcher at the University of Rome La Sapienza, Italy, and an expert on the crystallography and mineralogy of the tourmaline-supergroup minerals and the spinels. [1]: /embed/mml-math-1.gif

Cairncrossite is a new phyllosilicate species found in manganese ore on dumps of the Wessels Mine, Kalahari Manganese Field, South Africa. Associated minerals are richterite, sugilite, lizardite and fibrous pectolite. It occurs as radiating platy micaceous aggregates of up to 1 cm in size. Cairncrossite is colourless, appearing white, and the crystals are translucent to transparent with a white streak and vitreous to pearly lustre. The crystals are sectile before brittle fracture, with a Mohs hardness of 3. A perfect cleavage parallel (001) is observed. The calculated density is 2.486 g cm −3 . The mineral is biaxial positive with n α = 1.518(2), n β = 1.522(2), n γ = 1.546(2), 2 V obs = 33.9(6)° (2 V calc = 44.97°) at 589.3 nm and 24°C. The orientation of the indicatrix is Z ^ c * = 10°. The dispersion is weak ( r v ) and no pleochroism is observed. An intense light-blue fluorescence is emitted under shortwave UV radiation. Cairncrossite is triclinic, space group P 1 ¯ , a = 9.6265(5), b = 9.6391(5), c = 15.6534(10) A, α = 100.89(1), β = 91.27(1)°, γ = 119.73(1)°, V = 1227.08(13) A 3 , Z = 1. The strongest lines in the Gandolfi X-ray powder-diffraction pattern [ d in A( I )( hkl )] are 15.230 (100)(001), 8.290 (15)(1–10), 5.080(25)(003), 3.807(30)(004), and 3.045(20)(005). The chemical composition obtained by electron-microprobe analysis is Na 2 O 3.06, K 2 O 0.11, CaO 18.61, SiO 2 54.91, SrO 11.75, total 88.44 wt%. The relevant empirical formula, based on 16 Si atoms per formula unit ( apfu ) and TGA data is: Sr 1.99 K 0.02 Ca 5.81 Na 1.73 Si 16 O 55.84 H 30.33 . Taking variable sodium contents into account, the idealized structural formula is Sr 2 Ca 7–x Na 2x (Si 4 O 10 ) 4 (OH) 2 (H 2 O) 15–x with 0 ≤ x ≤ 1, and the simplified formula for sodium-rich crystals is SrCa 3 Na(Si 4 O 10 ) 2 (OH)(H 2 O) 7 with Z = 2. The structure of cairncrossite was refined on single-crystal X-ray data (Mo K a radiation) to R 1 = 0.047. Cairncrossite belongs to the gyrolite and reyerite mineral groups, it is characterized by sheets consisting of edge-sharing CaO 6 octahedra, which are corner-linked on both sides to silicate layers. These units are intercalated by layers formed by SrO 8 polyhedra, which are arranged in pairs via a common edge, and further bound to disordered NaO 6 polyhedra. A complex system of hydrogen bonds strengthens the linkage to adjacent silicate layers. Cairncrossite exhibits a two-phase endothermic weight loss of the H 2 O molecules in the range 25–400°C; however, the mineral shows a nearly complete rehydration capability up to 400°C. The new mineral is named in honour of Bruce Cairncross, Professor and Head of the Department of Geology, University of Johannesburg.

Pb-lawsonite, PbAl2[(OH)2|Si2O7]·H2O, space group Pbnm, was synthesized as crystals up to 15 μm × 5 μm × 5 μm in size by a piston cylinder technique at a pressure of ∼4 GPa and a temperature of 873 ± 10 K. Temperature-dependent powder and single-crystal X-ray diffraction (XRD) analyses partly using synchrotron radiation as well as Raman spectroscopic investigations reveal a phase transition around 445 K resulting in the Cmcm high-temperature structure. The transformation temperature is considerably higher than that of lawsonite around 273 K, which is characterized predominantly by proton order/disorder. The transition is confirmed using principal component analysis and subsequent hierarchical cluster analysis on both the powder XRD patterns and the Raman spectra. Furthermore, a non-uniform change is observed around 355 K, which is not as pronounced as the 445 K transition and apparently comes from enhanced hydrogen bonding, which stops the atom shifts in Pb-lawsonite. These are the same bonds that mainly characterize the phase transition in lawsonite around 273 K. In contrast, the structural transition of Pblawsonite at 445 K seems to originate from the interaction of the SiO4tetrahedra and AlO6octahedra framework with the Pb2+cation. The structural environment of Pb2+can be described by a 12-fold coordination above 445 K, which changes towards irregular ten-fold coordination below this temperature. An assignment of the O–H stretching Raman bands confirms moderately strong H bonds in Pb-lawsonite, whereas both strong and weak H bonds exist in lawsonite. Therefore, a further phase transition of Pblawsonite, similar to that of lawsonite around 273 K, is not expected.

The crystal structures of the secondary ferric iron minerals kamarizaite, Fe 3 3+ (AsO 4 ) 2 (OH) 3 · 3H 2 O, and tinticite, Fe 3 3+ (PO 4 ) 2 (OH) 3 · 3H 2 O, for which highly contradictory data on crystal symmetry were reported, were studied by a combination of single-crystal X-ray diffraction and Rietveld refinement (supplemented by chemical analyses and thermogravimetry), using type material of both species and additional samples from several other localities, including the type localities. The previously unknown crystal structure of kamarizaite was determined from single-crystal intensity data (Mo K α, 293 K, R ( F ) = 2.91 %; all H atoms detected) using a sample from the Le Mazet vein, Echassieres, Auvergne, France. The mineral is triclinic, space group P 1 ¯ (no. 2), with a = 7.671(2), b = 8.040(2), c = 10.180(2) A, α = 68.31(3), β = 75.35(3), γ = 63.52(3)°, V = 519.3(2) A 3 , Z = 2. Rietveld analyses of fine-grained kamarizaite collected underground at two different spots in Lavrion, Greece (Hilarion and Jean Baptiste areas) confirmed the structure model. Rietveld analyses of fine-grained tinticite from Tintic, Utah (USA), Bruguers (Spain) and Weckersdorf (Germany) demonstrate that kamarizaite and tinticite are triclinic and isotypic. A previously published structure model for tinticite, as well as the originally reported orthorhombic symmetry for kamarizaite, are shown to be incorrect. Refined unit-cell parameters of a cotype tinticite specimen from Tintic are: a = 7.647(1), b = 7.958(1), c = 9.987(1) A, α = 67.90(1), β = 76.10(1), γ = 64.10(1)°, V = 504.4(2) A 3 . Bruguers and Weckersdorf tinticite have very similar parameters. The common atomic arrangement is characterised by three unique, octahedrally coordinated Fe sites (on which Fe may be partially replaced by minor Al), two unique tetrahedrally coordinated T (As or P) sites, eight O, three O h , three O w and nine H sites. The topology features zig-zag chains along [ 1 ¯ 10 ] of dimers built of two edge-sharing FeO 6 octahedra corner-linked by a third FeO 6 octahedron. The chains are corner-linked by the T O 4 tetrahedra thus establishing a mixed octahedral-tetrahedral framework with a T :Fe ratio of 0.67, a pronounced layered arrangement parallel to (001) and narrow channels along [010]. Medium-strong to weak hydrogen-bonds provide additional strengthening of the structure. The topology is closely related to that of the recently described, triclinic aluminium phosphate afmite.

In the present work, Cu2+ substituted Co ferrite (CuxCo1-xFe2O4, x = 0.00, 0.25, 0.50, 0.75 and 1.00) nanoparticles embedded in SiO2 matrix were synthesized via a modified sol-gel method followed by high temperature annealing. The reaction progress was investigated by thermal analysis coupled with mass spectrometry and Fourier transformed infrared spectroscopy (FT-IR), while the formation of CuxCo1-xFe2O4/SiO2 nanocomposites (NCs) and of secondary phases as a result of the variation of Cu/Co molar ratios were investigated by powder X-ray diffraction analysis (PXRD) and FT-IR. The particle size and shape were studied by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). By varying the Cu/Co molar ratios, the dependence of phase specific parameters (crystallite size, cell parameter, density, porosity) and the evolution of particle shape and size at 1000 °C were investigated by TEM. The photocatalytic activity of the NCs by increasing the Cu content was evaluated through the degradation of Rhodamine B under UV-Vis light irradiation.

The possibility of producing polymer-bonded magnets with the aid of additive processes, such as 3D printing, opens up a multitude of new areas of application. Almost any structures and prototypes can be produced cost-effectively in small quantities. Extending the 3D printing process allows the manufacturing of anisotropic magnetic structures by aligning the magnetic easy axis of ferromagnetic particles inside a paste-like compound material along an external magnetic field. This is achieved by two different approaches: First, the magnetic field for aligning the particles is provided by a permanent magnet. Secondly, the 3D printing process itselfs generates an anisotropic behavior of the structures. An inexpensive and customizable end-user fused filament fabrication 3D printer is used to print the magnetic samples. The magnetical properties of different magnetic anisotropic Sr ferrite and SmFeN materials are investigated and discussed.

The crystal structure of synthetic BaMg(CO3)2whose mineral name is norsethite was re-investigated by single-crystal X-ray diffraction. Complementaryin situhigh- and low-temperature studies by means of vibrational spectroscopy (Raman, IR), powder X-ray diffraction techniques and thermal analyses were performed. Diffraction images (298 K) revealed weak superstructure reflections caused by the displacement of the O atoms in the earlier consideredRmstructure model (a = 5.0212(9), cnew= 2 cold= 33.581(6) Å ,Rc, Z = 6, R1 = 0.011, sinθ/λ < 0.99 Å–1). Thermal analyses reveal decarbonatization in two decomposition steps above 750 K, and the heat-flow curves (difference scanning calorimetry) give clear evidence of a weak and reversible endothermal change at 343±1 K. This agrees with a discontinuity in the IR and single-crystal Raman spectra. The changing trend of thec/aratio supports this discontinuity indicating a temperature-induced structural transition in the range between 343 and 373 K. As the change of the unit-cell volume is almost linear, the character of the transition is apparently second order and matches the mechanism of a subtle displacement of the oxygen atom position. The apparent instability of theRcstructure is also evidenced by the remarkably larger anisotropic displacement of the oxygen atom.

Fe^(2+)- and Mn^(2+)-rich tourmalines were used to test whether Fe^(2+) and Mn^(2+) substitute on the Z site of tourmaline to a detectable degree. Fe-rich tourmaline from a pegmatite from Lower Austria was characterized by crystal-structure refinement, chemical analyses, and Mössbauer and optical spectroscopy. The sample has large amounts of Fe^(2+) (~2.3 apfu), and substantial amounts of Fe^(3+) (~1.0 apfu). On basis of the collected data, the structural refinement and the spectroscopic data, an initial formula was determined by assigning the entire amount of Fe^(3+) (no delocalized electrons) and Ti^(4+) to the Z site and the amount of Fe^(2+) and Fe^(3+) from delocalized electrons to the Y-Z ED doublet (delocalized electrons between Y-Z and Y-Y): X(Na_(0.9)Ca_(0.1)) ^Y(Fe^(2+)_(2.0)Al_(0.4)Mn^(2+)_(0.3)Fe^(3+)_(0.2)) ^Z(Al_(4.8)Fe^(3+)_(0.8)Fe^(2+)_(0.2)Ti^(4+)_(0.1)) ^T(Si_(5.9)Al_(0.1))O_(18) (BO_3)_3^V(OH)_3 ^W[O_(0.5)F_(0.3)(OH)_(0.2)] with α = 16.039(1) and c = 7.254(1) Å. This formula is consistent with lack of Fe^(2+) at the Z site, apart from that occupancy connected with delocalization of a hopping electron. The formula was further modified by considering two ED doublets to yield: ^X(Na_(0.9)Ca_(0.1)) ^Y(Fe^(2+)_(1.8)Al_(0.5)Mn^(2+)_(0.3)Fe^(3+)_(0.3)) ^Z(Al_(4.8)Fe^(3+)_(0.7)Fe^(2+)_(0.4)Ti^(4+)_(0.1)) ^T(Si_(5.9_Al_(0.1))O_(18) (BO_3)_3 ^V(OH)_3 ^W[O_(0.5)F_(0.3)(OH)_(0.2)]. This formula requires some Fe^(2+) (~0.3 apfu) at the Z site, apart from that connected with delocalization of a hopping electron. Optical spectra were recorded from this sample as well as from two other Fe^(2+)-rich tourmalines to determine if there is any evidence for Fe^(2+) at Y and Z sites. If Fe^(2+) were to occupy two different 6-coordinated sites in significant amounts and if these polyhedra have different geometries or metal-oxygen distances, bands from each site should be observed. However, even in high-quality spectra we see no evidence for such a doubling of the bands. We conclude that there is no ultimate proof for Fe^(2+) at the Z site, apart from that occupancy connected with delocalization of hopping electrons involving Fe cations at the Y and Z sites. A very Mn-rich tourmaline from a pegmatite on Elba Island, Italy, was characterized by crystal-structure determination, chemical analyses, and optical spectroscopy. The optimized structural formula is ^X(Na_(0.6)□_(0.4)) ^Y(Mn^(2+)_(1.3)Al_(1.2)Li_(0.5)) ^ZAl_6 ^TSi_6O_(18) (BO_3)_3 ^V(OH)_3 ^W[F_(0.5)O_(0.5)], with α = 15.951(2) and c = 7.138(1) Å. Within a 3σ error there is no evidence for Mn occupancy at the Z site by refinement of Al ↔ Mn, and, thus, no final proof for Mn^(2+) at the Z site, either. Oxidation of these tourmalines at 700–750 °C and 1 bar for 10–72 h converted Fe^(2+) to Fe^(3+) and Mn^(2+) to Mn^(3+) with concomitant exchange with Al of the Z site. The refined ^ZFe content in the Fe-rich tourmaline increased by ~40% relative to its initial occupancy. The refined YFe content was smaller and the distance was significantly reduced relative to the unoxidized sample. A similar effect was observed for the oxidized Mn^(2+)-rich tourmaline. Simultaneously, H and F were expelled from both samples as indicated by structural refinements, and H expulsion was indicated by infrared spectroscopy. The final species after oxidizing the Fe^(2+)-rich tourmaline is buergerite. Its color had changed from blackish to brown-red. After oxidizing the Mn^(2+)-rich tourmaline, the previously dark yellow sample was very dark brown-red, as expected for the oxidation of Mn^(2+) to Mn^(3+). The unit-cell parameter α decreased during oxidation whereas the c parameter showed a slight increase.

Crystal structures, chemical (including light elements) and spectral data (optical and Mossbauer spectroscopies) were used to characterize coloured (brown, pink, green) tourmalines from three granitic pegmatites from the Moldanubian nappes (Konigsalm, Maigen and Blocherleitengraben; Lower Austria). The tourmalines can be classified as fluor-schorl, schorl, foitite, magnesiofoitite, olenite and "fluor-elbaite" with varying Li contents, up to ~ 1.2 wt% Li_2O. Coexisting minerals are quartz, plagioclase (up to An_7), microcline, garnet (spessartine-almandine), muscovite, biotite (annite), very rare lepidolite, apatite, monazite-(Ce), xenotime-(Y), allanite-(Ce) and zircon. The chemical composition of the Fe^(2+)-rich tourmaline samples (up to ~ 1.0 wt% TiO_2) varies from fluorschorl, with α = 15.987(2), c = 7.163(2) A to ^X(_(0.63)Na_(0.37)) ^Y(Fe^(2+)_(1.12)Al_(1.09)Mg_(0.56)Mn^(2+)_(0.08)Fe^(3+) _(0.07)Li_(0.02)Ti^(4+)_(0.01)Zn_(0.01)_(0.04)) ^Z(Al_(5.74)Mg_(0.26)) (BO_3)_3 [Si_(5.96)Al_(0.04)O_(18)] ^V(OH)_3 ^W[(OH)_(0.95)F_(0.05)], strongly dichroic (pink and blue) foitite, with α 15.9537(2), c = 7.1448(4) A, to ^X(_(0.51)Na_(0.49)) ^Y(Fe^(2+)_(0.97)Al_(0.93)Mg_(0.75)Fe^(3+)_(0.23)Mn^(2+) _(0.04)Li_(0.01)Ti^(4+)_(0.01)_(0.06))^Z(Al_(5.72)Mg_(0.28)) (BO_3)_3 [Si_(5.95)Al_(0.05)O_(18)]^V(OH)_3^W[(OH)_(0.91)O_(0.06)F_(0.03)], magnesiofoitite, with α = 15.9476(4), c = 7.1578(4) A. The chemical composition of the Al- and Lirich and Mn^(2+)-bearing (up to ~ 5.7 wt% MnO) samples varies from ^X(Na_(0.84)Ca_(0.02)_(0.14))^Y(Al_(1.35)Li_(0.78)Mn^(2+) _(0.65)Ti^(4+)_(0.01)_(0.21))^ZAl_6(BO_3)_3[Si_(5.92)Al_(0.04)B_(0.04)O_(18)]^V(OH)_3^W[F_(0.81)(OH)_(0.19)], "fluor-elbaite" with α = 15.8887(3), c = 7.1202(3) A, to ^X(Na_(0.76)Ca_(0.12)_(0.12))^Y(Al_(1.52)Li_(0.69)Mn^(2+) _(0.43)Fe^(2+)_(0.09)_(0.27))^ZAl_6(BO_3)_3 [Si_(5.71)B_(0.29)O_(18)]^V(OH)_3^W[F_(0.69)(OH)_(0.31)], B-rich "fluorelbaite", with α = 15.8430(3), c = 7.1051(3)A. A positive correlation between the and bond lengths in tourmalines where the Z site is only occupied by Al (R^2 = 0.617) is useful to correct the bond length for the inductive effect of the varying bond length. This is important for producing accurate assignments for the different 6-coordinated sites in tourmaline. On the basis of Sm-Nd (garnet, monazite), U-Th-Pb, and U-Pb ages (monazite), the pegmatites crystallised during the Variscan tectonometamorphic event in the Visean (339 4 Ma Maigen, 332 3 Ma Konigsalm). These ages are in the range of the earliest intrusions of the South Bohemian pluton (Rastenberg type durbachites). However, on the basis of the spatial relationship of the pegmatites and the Rastenberg type intrusions, a linkage of the intrusive body and the pegmatites is unlikely. Alternatively, the pegmatites may have evolved as granitic pegmatitic melts during decompression from the surrounding country rocks in the frame of exhumation of the Moldanubian nappes after the peak of the Variscan metamorphism.

Arsenohopeite, ideally Zn3(AsO4)2·4H2O, is the arsenate analogue of hopeite, Zn3(PO4)2·4H2O (it is isostructural with α-hopeite). It was found as a single colourless to blue crystalline grain from the Tsumeb mine, Namibia. The holotype specimen is ∼1 × 1 × 1 mm in size. Arsenohopeite is associated with tiny white fibres of an unidentified Zn- and As-bearing phase. It is orthorhombic, space group Pnma, with a = 10.804(2), b = 19.003(4), c = 5.112(1) Å, V = 1049.5(4) Å3 and Z = 4. Electron microprobe analysis yielded: ZnO 44.92, Fe2O3 0.92, MnO 0.51, MgO 0.20, CuO 0.02, As2O5 45.84 (wt.%). The empirical formula is (Zn2.80Fe0.06Mn0.04Mg0.03)Σ2.93(As1.01O4)2·4H2O, based on 12 oxygen atoms. Optically, the mineral is biaxial negative, with α = 1.598(2), β = 1.606(2), γ = 1.613(2) (white light) and 2Vcalc = 86°. It is not pleochroic or fluorescent. Arsenohopeite is translucent with a vitreous lustre. It is brittle, has an uneven fracture and (by analogy with hopeite) a cleavage that is perfect on {010}, good on {100} and poor on {001}. The calculated density is 3.420 g cm–3. The five strongest calculated powder diffraction lines are [d in Å (I)(hkl)]: 9.502 (100)(020), 2.926 (95)(241), 4.937 (50)(011), 4.110 (48)(230) and 3.567 (31)(240). The crystal structure of arsenohopeite has been solved by direct methods and refined in space group Pnma to R1 = 0.0353. Raman spectroscopy confirms the crystal-structure data and indicates the presence of weak hydrogen bonds.

Crystals of Zn(NO3)2· H2O and Mn(NO3)2· 2 H2O were synthesized by heating melts of the respective penta- or hexahydrates. Single crystal X-ray diffraction of the two highly hygroscopic phases reveals new sheet-structure types: Zn(NO3)2· H2O [Pbca,a= 9.722(1),b= 5.865(1),c= 17.799(3) Å (120 K),Z= 8,R1= 0.025]; Mn(NO3)2· 2 H2O [P212121,a= 5.921(1),b= 8.835(1),c= 22.882(3) Å (120 K),Z= 8,R1= 0.020]. Zn(NO3)2· H2O is built of only one kind of complicated, corrugated sheets held together by hydrogen bonds, while Mn(NO3)2· 2 H2O is built of alternating sheets with Mn in 6- and 7-fold coordination, respectively, again interconnected by hydrogen bonds. While in Zn(NO3)2· H2O the hydrogen bond system is quite clear-cut, this is not the case in Mn(NO3)2· 2 H2O. Contrary to expectation, the thermal expansion is not clearly largest perpendicular to the sheets in both compounds.In the well known structures of the nitrate dihydrates of Mg, Co and Ni new refinements allowed to locate the hydrogen atoms.Together with Mn(II) nitrate monohydrate and the dihydrates of Mg, Co, Ni, Zn and Cd the two new nitrates form an interesting group of sheet structures.

A new version of the Ga–Ni phase diagram was established based on the investigation of ten samples in the Ga-rich part by DTA, powder X-ray diffraction and EPMA. Two significant differences compared to the last version of the phase diagram were discovered. The most Ga-rich compound Ga4Ni was not found as such. Instead the existence of Ga7Ni3, as already described earlier in literature, was confirmed. Furthermore, the peritectic reaction GaNi + L → Ga3Ni2 was found at a temperature of 950 °C, which is more than 50 °C higher than the indicated literature value. At 80 at.% Ga, additional lines in the X-ray powder patterns, which were also reported in literature, suggest the presence of a further, possibly metastable Ga-rich phase. Although no single-crystal X-ray diffraction measurements could be performed, the Ga-rich phase could be characterized using a Ga5Pd type crystal structure including a refinement of the atomic parameters. The partial and integral enthalpies of mixing of liquid Ga–Ni alloys were determined at various temperatures (1031, 1134, 1246, 1261, 1321, 1388 °C) using a drop calorimetric technique. No significant temperature dependence of ΔmixH could be observed. The minimum was found at 52 at.% Ni with a value of −35 kJ/mol.

The previously uninvestigated atomic arrangements of six strontium arsenate(V) phases in the systems Sr-As-O- X ( X = H, Cl) have been determined. Single crystals of Sr 3 (AsO 4 ) 2 and Sr 5 (AsO 4 ) 3 Cl were grown from a borate and NaCl melt, respectively, whereas single crystals of α - and β -SrAs 2 O 6 and of Sr 5 -(AsO 4 ) 3 OH were obtained under hydrothermal conditions. Microcrystalline samples of Sr 2 As 2 O 7 were prepared by solid-state reaction of As 2 O 5 with SrCO 3 and, alternatively, by thermolysis of SrHAsO 4 . Crystal structure determinations based on powder X-ray diffraction data using the Rietveld method (Sr 2 As 2 O 7 ), and from single-crystal X-ray diffraction data (all other phases) revealed isotypism with known structure types (except β -SrAs 2 O 6 which represents a new structure type). Sr 3 (AsO 4 ) 2 crystallizes in the K 2 Pb(SO 4 ) 2 structure type; Sr 2 As 2 O 7 is isotypic with the high-temperature polymorphs of Ca 2 P 2 O 7 and Sr 2 V 2 O 7 , but itself shows no polymorphism; Sr 5 (AsO 4 ) 3 OH and Sr 5 (AsO 4 ) 3 Cl crystallize with the hydroxylapatite and chloroapatite structure, respectively; SrAs 2 O 6 is dimorphic. Like all other known M II As 2 O 6 metaarsenates ( M = Mn, Co, Ni, Sr, Pd, Cd, Hg, Pb), the α -polymorph crystallizes in the PbSb 2 O 6 structure type, whereas the novel β -polymorph is the first example of a M II As 2 O 6 superstructure with a doubled c -axis. Additional analytical methods using Raman spectroscopy and thermal analyses support the results of the X-ray structure work.

Florkeite is a new phillipsite-type zeolite. It was found in a Ca-rich xenolith from a quarry at the Bellerberg volcano near Ettringen, East Eifel volcanic area, Germany. The paragenesis includes tobermorite, thaumasite, willhendersonite, gismondine and ellestadite. It forms subparallel, short prismatic, pseudo-monoclinic crystals elongated along [100] and flattened on {010}, with a maximum length of 0.6 mm and a thickness of up to 0.1 mm. Additional forms are {100}, {001} and {201}. Florkeite is colourless, transparent, non-fluorescent and has a vitreous lustre and a white streak. It is brittle with irregular fracture, the calculated density is 2.266 gcm−3. Optically, it is biaxial negative with n α = 1.506(2), n β = 1.514(2), n γ = 1.518(2), 2 V = 71.0(5) ° at 589.3 nm and 297 K. No pleochroism is observed. Orientation of the indicatrix is X ∧ c = 43°, Y ∧ b = 40° and Z ∧ a = 8°. Electron microprobe analyses yielded (wt%): Na2O 2.32, K2O 10.29, MgO 0.04, CaO 8.43, Al2O3 30.20, SiO2 35.29, sum 86.57. A H2O content of 15.57 wt% was derived from the single-crystal structure refinement. The empirical formula calculated on the basis of Al + Si = 16 pfu is K2.96Ca2.04Na1.02 Mg0.01[Al8.03Si7.97O31.97] · 11.72H2O and the ideal formula can be given as K3Ca2Na[Al8Si8O32] · 12H2O. Florkeite is triclinic, space-group P 1 (no. 2), the unit-cell parameters in phillipsite-type setting are a = 19.965(1), b = 14.274(1), c = 8.704(1) A, α = 88.37(1), β = 125.08(1), γ = 89.57(1)°, V = 2028.2(3) A3, Z = 2 and the a : b : c ratio is 1.399 : 1 : 0.610. The five strongest lines in the powder X-ray diffraction pattern are ( d in A/ I obs): 3.235 / 100, 3.162 / 80, 3.135 / 80, 2.736 / 60, 4.956 / 45. The single-crystal structure refinement ( R 1 = 4.39 %) confirmed that the structure of florkeite is the triclinically distorted analogue of phillipsite with a complete (Al, Si) ordering at the T -sites of the framework (mean T (Al)–O: 1.731–1.743 A and T (Si)–O: 1.615–1.631 A), which reduces the topochemical symmetry to B 2/ b . The K+ cations are placed near the centre of 8-rings of the oto units, the Ca2+ and Na+ cations are located within the phi units. The doubling of the a -parameter and the reduction of the real symmetry to P 1 (is caused by an ordering of the extra-framework cations and H2O molecules within the 8-ring channel system along [100], basically Ca– □ –Ca, Na–Ca–Na and H2O–K–H2O. The (Al, Si) ordering is attributed to low-thermal genetic conditions within the Ca-rich xenolithic host, also indicated by the paragenesis with willhendersonite. Holotype material of florkeite has been deposited at the mineral collection of the Naturhistorisches Museum Wien, Austria. The mineral is named in honour of the German mineralogist and crystallographer Otto Wilhelm Florke (born 1926).

Friedrichbeckeite is a new milarite-type mineral. It was found in a single silicate-rich xenolith from a quarry at the Bellerberg volcano near Ettringen, eastern Eifel volcanic area, Germany. It forms thin tabular crystals flattened on {0001}, with a maximum diameter of 0.6 mm and a maximum thickness of 0.1 mm. It is associated with quartz, tridymite, augite, sanidine, magnesiohornblende, enstatite, pyrope, fluorapatite, hematite, braunite and roedderite. Friedrichbeckeite is light yellow, with white to light cream streak and vitreous lustre. It is brittle with irregular fracture and no cleavage, Mohs hardness of 6, calculated density is 2.686 gcm−3. Optically, it is uniaxial positive with nω = 1.552(2) and ne = 1.561(2) at 589.3 nm and a distinct pleochroism from yellow (//ω) to light blue (//e). Electron microprobe analyses yielded (wt.%): Na2O 2.73, K2O 4.16, BeO 4.67, MgO 11.24, MnO 2.05, FeO 1.76, Al2O3 0.15, SiO2 73.51, (Σ CaO, TiO2 = 0.06) sum 100.33 (BeO determined by LA-ICP-MS). The empirical formula based on Si = 12 is K0.87 Na0.86 (Mg1.57Mn0.28Fe0.24)Σ2.09 (Be1.83 Mg1.17)Σ3.00 [Si12O30], and the simplified formula can be given as K (□0.5Na0.5)2 (Mg0.8Mn0.1Fe0.1)2 (Be0.6 Mg0.4)3 [Si12O30]. Friedrichbeckeite is hexagonal, space-group P6/mcc, with a = 9.970(1), c = 14.130(3) A, V = 1216.4(3) A3, and Z = 2. The strongest lines in the X-ray powder diffraction pattern are (d in A / I obs / hkl): 3.180 / 100 / 121, 2.885 / 70 / 114, 4.993 / 30 / 110, 4.081 / 30 / 112, 3.690 / 30 / 022. A single-crystal structure refinement (R1 = 3.62 %) confirmed that the structure is isotypic with milarite and related [12] C [9] B 2 [6] A 2 [4] T23 [[4] T112O30] compounds. The C-site is dominated by potassium, the B-site is almost half occupied by sodium, and the A-site is dominated by Mg. The site-scattering at the T2-site can be refined to a Be/(Be + Mg) value close to 0.61; the T1-site is occupied by Si. Micro-Raman spectroscopy reveals an increasing splitting of scattering bands around 550 cm−1 for friedrichbeckeite. The mineral can be classified as an unbranched ring silicate or as a beryllo-magnesiosilicate. With respect to the end-member formula K (□0.5Na0.5)2 Mg2 Be3 [Si12O30] friedrichbeckeite represents the Mg-dominant analogue of almarudite, milarite or oftedalite. The mineral and its paragenesis were formed during pyrometamorphic modifications of the silicate-rich xenoliths enclosed in Quaternary leucite-tephritic lava of the Bellerberg volcano. Holotype material of friedrichbeckeite has been deposited at the mineral collection of the Naturhistorisches Museum Wien, Austria. The mineral is named friedrichbeckeite in honour of the Austrian mineralogist and petrographer Friedrich Johann Karl Becke (1855–1931).

The section Hf5Ge4–Zr5Ge4 shows the existence of extended ternary solid solutions based on the binary compounds Hf5Ge4 (Pearson symbol: oP36) and Zr5Ge4 (Pearson symbol: tP36). The corresponding homogeneity ranges have been determined experimentally at 1350 °C. Partial ordering of the metal atoms at the three crystallographically independent metal sites of the structures was investigated by means of powder X-ray diffraction (XRD) followed by Rietveld refinement as well as by single crystal XRD. The two metals Hf and Zr exhibit site preferences throughout their respective homogeneity ranges. Using a simple thermodynamic model (“compound energy model”) and employing ground state energies of hypothetical ordered compounds calculated from ab initio density functional theory, the experimentally observed site fraction data were reproduced with high accuracy. The obtained Gibbs energies were furthermore used to calculate the stability ranges of the two different phases at 1350 °C. The possible benefit of this approach for the prediction of phase stability and for the Calphad-type modeling of higher-order systems is discussed.

An Al-rich tourmaline from the Sahatany Pegmatite Field at Manjaka, Sahatany Valley, Madagascar, was structurally and chemically characterized. The combination of chemical and structural data yields an optimized formula of X (Na0.53Ca0.09□0.38) Y (Al2.00Li0.90Mn2+0.09Fe2+ 0.01) Z Al6 (BO3)3 T [Si5.61B0.39]O18 V (OH)3 W [(OH)0.6O0.4], with a = 15.777(1), c = 7.086(1) A ( R 1 = 0.017 for 3241 reflections). The 〈 T –O〉 distance of ~ 1.611 A is one of the smallest distances observed in natural tourmalines. The very short 〈 Y –O〉 distance of ~ 1.976 A reflects the relatively high amount of Al at the Y site. Together with other natural and synthetic Al-rich tourmalines, a very good inverse correlation ( r 2 = 0.996) between [4]B and the unit-cell volume was found. [4]B increases with the Al content at the Y site approximately as a power function with a linear term up until [4]B ≈ Si ≈ 3 apfu and Y Al ≈ 3 apfu, respectively, in natural and synthetic Al-rich tourmalines. Short-range order considerations would not allow for [4]B in solid solution between schorl and elbaite, but would in solid solutions between schorl, “oxy-schorl”, elbaite, liddicoatite, or rossmanite and hypothetical [4]B-rich tourmaline end-members with only Al3+ at the Y site. By plotting the [4]B content of synthetic and natural Al-rich tourmalines, which crystallized at elevated PT conditions, it is obvious that there are pronounced correlations between PT conditions and the [4]B content. Towards lower temperatures higher [4]B contents are found in tourmaline, which is consistent with previous investigations on the coordination of B in melts. Above a pressure of ~ 1000–1500 MPa (depending on the temperature) the highest observed [4]B content does not change significantly at a given temperature. The PT conditions of the formation of [4]B-rich olenite from Koralpe, Eastern Alps, Austria, can be estimated as 500–700 MPa/630 °C.

Single crystals of the chabazite-type zeolite mineral willhendersonite, KCaAl 3 Si 3 O 12 ·5H 2 O (from Bellerberg, eastern Eifel district, Germany), were studied by X-ray diffraction methods between 100 and 500 K. The zeolite shows a phase transition from triclinic to rhombohedral symmetry between 350 and 375 K under dry nitrogen and between 450 and 475 K under humid air. Under these conditions, the unit-cell parameters change from P 1 at 350 K [ a , b , c (A); α, β, γ (°); V (A 3 ) = 9.210, 9.210, 9.405; 92.75, 92.80, 90.80; 795.8] to R 3 at 375 K ( a = 9.380 A, α = 91.40°, V = 824.5 A 3 ), and from P 1 at 450 K [ a , b , c (A); α, β, γ (°); V (A 3 ) = 9.215, 9.215, 9.415; 92.65, 92.85, 90.75; 797.5] to R 3 at 475 K ( a = 9.375 A, α = 91.35°, V = 823.8 A 3 ), respectively. The crystal structures were refined based on X-ray diffraction data collected at room temperature [ P 1; a , b , c (A); α, β, γ (°); V (A 3 ) = 9.248(5), 9.259(5), 9.533(5); 92.313(5), 92.761(5), 89.981(5); 814.7(8)], at 373 K [ P 1; a , b , c (A); α, β, γ (°); V (A 3 ) = 9.205(5), 9.231(5), 9.442(5); 92.550(5), 93.086(5), 90.519(5); 800.3(8)], and at 423 K [ R 3, a = 9.411(4) A, α = 91.48(1)°, V = 832.7(6) A 3 ]. Upon heating, the elliptical 8-rings of willhendersonite expand to a triangular shape in the rhombohedral structure with upper and lower rings in the double 6-ring (D6R) twisted by 60° to each other corresponding to the center of symmetry in the center of the D6R. The changes in the framework are accompanied by migration of cations, partly assuming unfavorably low coordinations in the high temperature structure due to the loss of H 2 O molecules. Rehydration at room temperature yields the triclinic structure of willhendersonite, although the single crystals become polysynthetically twinned.

Mg(NO3)2, Co(NO3)2 and Ni(NO3)2 were obtained as tiny crystals by dehydration of melts of the respective hydrates in the range 410–450 K. Structure determinations and refinements are based on single crystal X-ray data (CCD area detector) measured at 120–370 K. Crystal parameters at 120 K: Mg(NO3)2: R−3, a = 10.474(1), c = 38.782(4) Å, Z = 36, R 1 = 0.028; Co(NO3)2: R−3, a = 10.445(1), c = 12.769(2) Å, Z = 12, R 1 = 0.019; Ni(NO3)2: R−3, a = 10.332(1), c = 12.658(2) Å, Z = 12, R 1 = 0.025. Co(NO3)2 and Ni(NO3)2 are isotypic; the structure of Mg(NO3)2 is closely related, although it is not simply a stacking variant – it forms a new structure type. In all three compounds the MO6 octahedra share all corners with the NO3 groups to form framework structures; any edge sharing is thereby avoided. The geometries of the structures are also discussed in relation to a simple theoretical cubic structure (space group Pa−3) with the same connection pattern of the MO6 and NO3 building units. Neither X-ray single crystal and powder work nor differential thermoanalytical investigations indicated polymorphism in the temperature range investigated.

Allanpringite is a new ferric iron phosphate with the ideal formula Fe3(PO4)2(OH)3·5H2O, and is closely related to wavellite, Al3(PO4)2(OH)3·5H2O. Type locality is the dump of the abandoned Grube Mark near Essershausen, ca. 5 km SE of Weilburg/Lahn, Taunus, Hesse, Germany. The mineral occurs as pale brown-yellow, 010] acicular, invariably twinned (by non-merohedry) crystals which are always intergrown to form bundles of subparallel individuals. The maximum length of crystals is ca. 1.5 mm (usually much smaller); bundles can reach up to about 2 mm. The mineral is associated with beraunite (reddish “oxiberaunite” variety), cacoxenite, strengite and cryptomelane. Allanpringite is translucent to transparent, its streak is white with a pale yellowish tint, and it has a vitreous lustre. It shows a perfect cleavage parallel to the morphological elongation and one good cleavage parallel to {010}. It is brittle and has an uneven fracture, a Mohs hardness of ~3, and D (meas.) = 2.54(2) g/cm3, D (calc.) = 2.583 g/cm3 (for empirical formula). Optically, it is biaxial positive, with α = 1.662(5), β = 1.675(5), γ = 1.747(5), 2 Vγ (calc.) = 48°; pleochroism is strong: X colourless, Y colourless, Z dark yellow; absorption Z>>X~Y; orientation XYZ = ** b (pseudo-orthorhombic); no visible dispersion. Electron microprobe analysis yielded (wt.%): Fe2O3 47.84, Al2O3 0.34, Mn2O3 0.04; CuO 0.08, P2O5 28.56, F 0.02, H2Ocalc 23.49, less O≡F 0.01, total 100.36. The empirical formula is (Fe2.98Al0.03)(PO4)2(OH3.02F0.01)·4.97H2O, based on 16 O atoms. Allanpringite is monoclinic, space group P 21/ n , with a = 9.777(3), b = 7.358(2), c = 17.830(5) A, β = 92.19(4)°, V = 1281.7(6) A3 (single-crystal data) and Z = 4. Strongest lines in the X-ray powder diffraction pattern are [ d (A), I , hkl ]: 8.90 (100) (002), 8.41 (60) (10-1, 101), 5.870 (50) (110), 3.600 (50) (021, 02-1), 3.231 (80) (204, 12-2). The crystal structure has been determined using single-crystal X-ray diffraction data (Mo K α radiation, CCD area detector) obtained from a twinned fragment ( R ( F ) = 13.3%). The structure of allanpringite is a monoclinically distorted, pseudo-orthorhombic variant of the orthorhombic structure of its Al-analogue wavellite, Al3(PO4)2(OH,F)3·5H2O. Chains of corner-sharing, distorted Fe(O,OH,H2O)6 octahedra parallel to [010] are corner-linked by PO4 tetrahedra. Channels, also parallel to [010], host a positionally split water molecule. Average Fe-O distances of the three non-equivalent Fe atoms range between 2.014 and 2.021 A. Single-crystal laser-Raman spectroscopy confirms an overall weak hydrogen bonding scheme. The structure of allanpringite is also related to those of kingite and mitryaevaite. The amorphous santabarbaraite has a chemical formula basically identical to that of allanpringite. The name honours Dr. Allan Pring, eminent Australian mineralogist.

Leogangite, ideally Cu10(AsO4)4(SO4)(OH)6·8H2O, was found on sample material from mine dumps of the Danielstollen and Inschlagalm in the Schwarzleo valley, both part of the polymetallic ore district of Leogang, Salzburg province, Austria. It is intergrown with olivenite and malachite, all together coating small voids within a tennantite-bearing dolomite breccia, and is assumed to have formed as an alteration product of arsenic-rich fahlore. Associated minerals are tyrolite, parnauite, strashimirite, euchroite, brochantite, langite, posnjakite, and devilline. The new mineral crystallizes with monoclinic symmetry, space group C2/c (no. 15), with a=21.770(7) A, b=12.327(4) A, c=10.720(3) A, β=92.85(1)°, V=2873(2) A3, Z=4, and a calculated density of 3.55 g·cm−3. Leogangite exhibits a thin tabular habit with aggregates of platelets flattened on {100} and elongated along [010], measuring up to 0.1 mm in length, 0.05 mm in width, 0.01 mm in thickness. A perfect cleavage parallel to (100) can be observed. It is transparent, green with a bluish tint, the streak is light green, and it is optically negative with 2V=18(2)°. The refractive indices nx, ny, and nz are 1.590(2), 1.740(2), and 1.744(2), the optical orientation is X=a*, Y=b, Z=c, and the pleochroism is blue-green (X) to pale green (Y, Z). Typical microprobe analyses give (wt%) CuO 49.6–52.9, As2O5 28.5–31.1, SO3 4.9–5.4, which is equivalent to Cu9.94(As0.99Si0.01O4)4(S0.99O4)(OH)6·8.89H2O as the average composition based on 20+3 oxygens. The strongest reflections of the X-ray powder diffraction pattern are (dobs, I/Iobs, hkl): 10.85, 100, (200); 2.630, 60, (\({\it 20}{\bar {\it 4}}\)); 5.44, 50, (400); 3.625, 50, (600); 3.090, 40, (023). The structure of the mineral was refined to R1=0.095 for 1768 unique reflections with \(F^2_{\rm o} > 4\sigma(F^2_{\rm o})\) and is a new representative of the rare [5]-coordinated Cu2+ compounds with edge-sharing CuO5 square pyramids. The main motif consists of [Cu4O14] tetramers. Together with the AsO4 tetrahedra and the remaining CuO5 polyhedron they build complex heteropolyhedral layers parallel to (100), which are linked by the SO4 tetrahedron and parts of the hydrogen bonds along the a-axis, thus forming a complex open framework structure. Chemical, optical and X-ray powder pattern characteristics are the distinguishing features to similar minerals like parnauite, tyrolite, or clinotyrolite.

Two new layered gallophosphate-oxalate materials have been prepared hydrothermally using ethylenediamine and oxalic acid as structure-directing agents. The compounds (C 2 N 2 H 1 0 ) 2 [Ga 2 (C 2 O 4 ) 2 (HPO 4 ) 3 ].H 2 O 1 and (C 2 N 2 H 1 0 ) 3 -[Ga 4 (C 2 O 4 ) 4 (HPO 4 ) 4 (H 2 PO 4 ) 2 ] 2 are closely related, consisting of anionic double chains built of alternating pairs of GaO 6 and HPO 4 polyhedra. These double chains are linked via bridging HPO 4 or H 2 PO 4 tetrahedra to form corrugated layers containing eight-membered rings. The oxalate group acts as a bidentate ligand to each of the GaO 6 octahedron. The corrugated layers are held together by strong to weak hydrogen-bonding interactions between oxalate groups, water and diprotonated ethylenediamine molecules, and the framework components. The compounds were characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and infrared and Raman spectroscopy. Crystal data for 1: monoclinic, space group P2 1 /c (No. 14), a = 6.355(1) A, b = 39.362(8) A, c = 9.249(2) A, β = 106.7(1)°, Z= 2. Crystal data for 2: triclinic, space group P1 (No. 2), a = 8.730(1) A, b = 11.575(1) A, c = 11.696(1) A, a = 115.12(1)°, β = 90.07(1)°, y = 111.23(1)°, Z = 2.

The crystal structure of synthetic carlinite, Tl 2 S, was re-determined by single crystal and powder X-ray diffraction methods. The cell parameters obtained from Rietveld refinement are a =12.150(2) A, c =18.190(4) A, V =2325.5(7) A 3 . A single crystal data refinement proved Tl 2 S crystallizing in the trigonal space group R 3 with M =440.8gmol −1 , Z =27, R =0.076, and w R =0.145. The atomic arrangement found is that of a strongly deformed anti -CdI 2 type, but the deformation is clearly different from that given by previous workers. In the five crystallographically different STl 6 octahedra the S–Tl distances vary between 2.82 and 3.09A, the Tl–Tl edges between 3.52 and 4.58A. The common features of these octahedra are (i) each one with a definitely smaller vs larger Tl 3 face in trans -position, both faces parallel or sub-parallel (00.1), and (ii) each three shorter and longer S–Tl distances to the atoms of the larger and smaller Tl 3 faces, respectively. The Tl–Tl contacts between different Tl 2 S sheets are on the average definitely shorter than the ones within the sheet and they can be smaller than the Tl–Tl contacts in the small Tl 3 faces of the STl 6 octahedra. The atomic arrangement indicates that the single electron pairs of the monovalent Tl atoms are not arranged all parallel to the z -axis, as one would expect for Tl 2 S with an ideal anti -CdI 2 structure. The surrounding of the S atoms resembles that of one-third of the Cl atoms in yellow InCl. The absorbance of Tl 2 S is very low at wave numbers approximately −1 .

A new band assignment of the IR spectrum of mullite is proposed on the basis of FTIR powder spec- troscopy of Al-Si, Al-Ge, and Ga-Ge compounds and polarised FTIR single-crystal spectroscopy of oriented ultrathin Czochralski-grown Al-Si 2:1-mullite slabs. The structural parameters of the mullite compounds were obtained from a single-crystal data refinement (Al-Si 2:1) and from Rietveld powder data refinements in space group Pbam. The refined chemical compositions varied from x = 0.31 (Ga-Ge), x = 0.34 (Al-Si) to x = 0.36 (Al-Ge) and x = 0.41 (Al-Si 2:1) with respect to the general mul- lite formula VI M3+ 2( IV T3+ 2+2x IV T4+ 2-2x)O10-x (M = Al, Ga; T = Al, Si, Ga, Ge). The FTIR powder spectra in the 1400-400 cm-1 range of Al-Si, Al-Ge, and Ga-Ge mullite compounds are char- acterised by three groups of bands designated as (a), (b) and (c). The deconvolution of the absorption features in the whole spectral range requires a minimum number of nine fitted bands. For Al-Si mullite, group (a) bands centre in the 1200-1100 cm-1 range, group (b) in the 1000-700 cm-1, and group (c) in the 650-400 cm-1 region. A strong shift of group (a), (b), and (c) bands towards lower wavenumbers exist in Al-Ge and Ga-Ge mullite with respect to Al-Si mullite. This is explained with the increasing size of the polyhedra in replacing Si by Ge and Al by Ga. The orientation-dependent bands in the spectra of the Al-Si 2:1-mullite single-crystal slabs can be clearly corre- lated with the fitted bands of the powder spectra. Due to the band shift and the polarisation behaviour, group (a) bands are assigned to high-energy Si-O and Ge-O stretching vibrations occurring along the extremely short bonds of the respective tetrahedral units within the (001) plane. Group (b) bands are essentially determined by stretching vibra- tions of Al and Ga on T-sites and T-O-T bending vibrations, while group (c) bands are due to stretching vibrations of Al and Ga in octahedral coordination and to O-T-O bending vibrations. On the basis of the present band assign- ment the lattice vibrational region of sillimanite is shortly discussed.

Batiferrite, ideally Ba[Ti2Fe10]O19, was found in the Quaternary volcanic rocks near Udersdorf, Graulai, and Altburg, western Eifel area, Germany. The new mineral typically occurs as euhedral platy grains in cavities of melilite- and leucite-nephelinite basalts. Associated minerals are hematite, magnetite, titanite, gotzenite, clinopyroxene, nepheline, and biotite. It exhibits a hexagonal tabular habit flattened on {0001}, diameter 0.5–1 mm, thickness 20–125 μm, and {10&1macr;3}, {10&1macr;0} as observable forms. The mineral is opaque, of black color with submetallic lustre, and shows a ferrimagnetic behavior. VHN50 is 793 with a range of 710–841 from ten indentations. The quantitative reflectance measurements of Ro/Re on oriented grains in air and oil immersion, respectively, are [%]: for 470 nm 22.1/20.1 and 8.4/7.1, for 546 nm 21.0/19.4 and 7.8/6.6, for 589 nm 20.2/18.8 and 7.4/6.3, and for 650 nm 19.3/18.3 and 6.8/5.9. The bireflectance is distinct (air) to weak (oil), and parallel (0001) a moderate anisotropy with straight extinction can be observed. Typical microprobe analyses give [wt%] K2O 0.28–0.33, Na2O 0.17–0.20, SrO 0.46–0.55, BaO 11.80–12.17, MgO 1.27–1.47, Al2O3 0.31–0.33, TiO2 13.11–13.63, MnO 2.38–2.57, Fe2O3 61.36–63.12, FeO 5.49–5.86 (Fe3+/Fe2+ calculated for charge compensation), which is equivalent to (Ba0.84Na0.06K0.06Sr0.05)1.01(Fe8.48 3+Fe0.86 2+Ti1.82Mg0.37Mn0.37Al0.06)11.96O19 as the average composition based on 19 oxygen atoms. Batiferrite is a magnetoplumbite-type mineral with hexagonal symmetry, space group P6 3 /mmc (no. 194), a = 5.909(1) A, c = 23.369(4) A, V = 706.6(2) A3, Z = 2, and a calculated density of 5.016 gcm−3. The structure was refined to R1 = 0.031 for 278 unique reflections with Fo 2 > 4σ (Fo 2) and R1 = 0.079 for all 452 unique observations using single crystal X-ray data. The strongest reflections of the X-ray powder diffraction pattern are [d obs, I/Io, (hkl)]: 2.631, 100, (114); 2.799, 80, (107); 1.478, 70, (220); 2.429, 60, (203); 1.672, 50, (217). The new mineral is comparable to the other Ba containing magnetoplumbite-type minerals haggertyite and hawthorneite, the iron content, however, is much higher and in the range of magnetoplumbite. The large cation site (A) is dominated by Ba, and four of the five remaining crystallographic cation sites in the structure are dominated by Fe (M1, 2, 3, 5), the octahedrally coordinated M4-site is dominated by Ti. No oxygen vacancy on the O3-site like in plumboferrite can be observed. Batiferrite is named for its main chemical composition and the relationship to the M-type hexaferrites (polytype 5H).

Nesquehonite, MgCO3 · 3H2O, has been observed from Sounion, Lavrion mining district, Greece as a late alteration product in crystals up to 4 mm in size. The structure was refined in P21/n, Z = 4, to R = 0.032 using CCD X-ray single-crystal data of a twinned specimen showing orthorhombic pseudosymmetry. The precise cell parameters a = 7.701(1) A, b = 5.365(1) A, c = 12.126(2) A, β = 90.41(1)°, and V = 501.0(1) A3 were obtained from a Rietveld refinement of high resolution X-ray powder data with a calculated density of 1.835 gcm−3. The atomic coordinates of the Mg, C and O atoms are in accordance to published data, the hydrogen bond system, however, could now be established on the basis of experimentally determined H positions. The structure of nesquehonite is characterized by infinite chains along [010], formed by cornersharing MgO6 octahedra. Within the chains, CO3 groups link three MgO6 octahedra by two common corners and one edge, which causes strong distortions of the involved polyhedra. These chains are interconnected via hydrogen bonds only: each Mg atom is coordinated by two H2O ligands, and one free water molecule is situated between the chains. Mean bond lengths are 2.076 A for Mg-O and 1.283 A for C–O, the aplanarity of the carboate group is 0.025(3) A Of the six hydrogen bonds, five are usual ones with O–H⋯O from 2.738(2) A to 2.820(2) A the sixth one is found to be bifurcated.

The compounds Ca2(SeO3)(Se2O5), Ba(SeO3), and Ba(Se2O5) were obtained at low-hydrothermal conditions from aqueous solutions of SeO2 by reaction with the respective earth alkaline carbonate. The crystal structures were determined by direct methods from single crystal X-ray diffraction data. Ca2(SeO3)(Se2O5): space group P*, Z=2, a=5.517(1), b=8.210(2), c=8.716(2) A, α=92.47(2), β=95.92(2), γ=97.15(2)°, V=389.0(2) A3, R1=0.017; Ba(SeO3): space group P21/m, Z=2, a=4.677(2), b=5.645(2), c=6.851(3) A, β=107.16(2)°, V=172.8(1) A3, R1=0.022, Ba(Se2O5): space group P21/c, Z=4, a=4.553(1), b=11.724(3), c=9.758(2) A, β=92.66(2)°, V=520.3(2)A3, R1=0.027. All three compounds have framework structures; in the case of Ca2(SeO3)(Se2O5), subunits of edge-sharing CaOn polyhedra forming sheets parallel to (010) can be emphasized. Ba(SeO3) belongs to the structure type of KClO3. In Ba(Se2O5), chains of face-sharing BaO9 polyhedra along [100] are present. The calcium atoms are 7- and 8-coordinated with mean Ca–O bond lengths of 2.42 and 2.48 A, the barium atoms have nine oxygen ligands with mean Ba–O bond lengths of 2.87 A.

A sample of the zeolite paulingite from the locality Vinarická Hora was investigated by means of chemical, thermal, powder and single crystal X-ray methods. The fully transparent, colourless to pale yellow crystals exhibit the form {110} and occur together with phillipsite. The chemical composition is (Ca2.57K2.28Ba1.39Na0.38)(Al11.55Si30.59O84)·27H2O, Z = 16 with minor amounts of Mg (−3, and the observed refractive index is 1.482(2). The dehydration behaviour is characterized by a main weight loss from 24–190°C (−11.2 wt.%, ≅ 21H2O) and a minor weight loss from 190–390°C (−3.1 wt.%, ≅ 6H2O). The rehydration capability was proven up to 150°C. The dehydration process during the main weight loss is accompanied by a reduction of the cell volume of 11%. The refined lattice parameters of the X-ray powder data are a a = 35.1231 (5) Å and a = 33.7485(8) Å of an untreated and a dehydrated sample, respectively. A breakdown of the paulingite structure can be observed while the remaining water content decomposes. The single crystal X-ray refinement of this chemically different sample material derived three main cation positions, which are inside a so called paulingite or π-cage (Ca), between 8-rings of neighbouring π-cages (Ba), and in the centre of the non-planar 8-rings of the γ-cage (K). Further partially occupied cation positions (Ca,Na) were located in the planar 8-rings of the α- and γ-cages. No positions within the double 8-membered rings were detected. The water is localized around the main cation positions and in three clusters of partially occupied sites.

The structure of Al2GeO4(OH)2 [C2/c; a = 5.4197(3) Å, b = 8.2464(3) Å, c = 9.3187(3) Å, β = 110.933(3); Z = 4] was refined by X-ray Rietveld methods. It contains GeO4 tetrahedra having all four O atoms in common with an AlO2OH framework built from AlO4(OH)2 octahedra sharing three edges. The H atom could be located only approximately. The coordinations of the atoms are mostly as in topaz, Al2SiO4(F,OH)2, and its synthetic OH endmember, but the arrangement of the oxygen atoms is that of a distorted cubic close-packing, while in topaz it is based on a close-packing of the type ABAC.

Fur die Aufbewahrung des basischen Kalziumkarbonats (BCC) eignen sich am besten trockene Bedingungen. Unter hoherer Luftfeuchtigkeit findet eine Umwandlung des Materials in ein Vaterit-Typ Kalziumkarbonat statt. Wenn das BCC allerdings unter trockner Atmosphare erhitzt wird, dehydriert und dehydroxiliert dieses in ein Kalzit-Typ Kalziumkarbonat. Aus der dehydrierten Modifikation entsteht kein BCC, sondern es wandelt sich ebenfalls in das Vaterit-Typ Kalziumkarbonat um. Diese Informationen wurden mit Pulver-Rontgendiffraktometrie (pXRD) bestatigt. Eine Elektronenmikroskopie-Aufnahme von diesem Vaterit-Typ Kalziumkarbonat zeigt eine Pseudomorphose von Vaterit nach BCC. Aufgrund der erhaltenen und berechneten Gewichtsverluste des BCC und der Daten aus der Literatur, erhalt man eine Diskrepanz in der chemischen Formel. Der Gewichtsverlust fur (OH)2 + 1.5H2O sollte 14.9 wt% betragen. Der gemessene Gewichtsverlust von 12.3 wt% stimmt mit dem theoretischen Verlust des Monohydrats uberein, somit kann die Formel als Ca3(CO3)2(OH)2.H2O angegeben werden. Das Pulver wurde auch mit einer selbst filtrierten Probe aus einer Suspension verglichen. IR- und pXRD-Messungen zeigen keine Unterschiede der zwei Proben. Einzig Spuren von Kalzit, Vaterit und Portlandit sind in der Suspension enthalten. Auserdem wurden Versuche mit unterschiedlichen Waschlosungen nach der Filtration durchgefuhrt. Die Ergebnisse zeigen nur geringe Unterschiede. Die Strukturbestimmung aus Pulverdaten ergibt eine monokline Elementarzelle mit der Raumgruppe Pc und den Zellparametern a=8.661(1) A, b=6.557(1) A, c=7.078(1) A, s=90.08(1)° und V = 401.97(4) A3. Das Strukturmodell von BCC weist Ahnlichkeiten mit den Strukturen von Portlandit, Vaterit und Hydromagnesit auf.