The article presents a crystal-chemical description of the second occurrence of the P21/n modification of sampleite, NaCaCu5(PO4)4Cl·5H2O, discovered at the Kester tin deposit. The formation of this mineral is genetically associated with low-temperature oxidation processes of primary copper, zinc, and tin sulfides, as well as with the formation of later Cu- and Zn-phosphates such as batagayite, epifanovite, and sergeysmirnovite. The positions of hydrogen atoms in the structure of sampleite were calculated using the density functional theory method. To assess the reliability of the theoretical calculations, a comparison between the actual and theoretical IR spectra was conducted. Sampleite formed during the hydrothermal alteration stage of Sn, Cu, and Zn sulfide minerals and coexisted with epifanovite, NaCaCu5(PO4)4[AsO2(OH)2]·7H2O. Epifanovite is undoubtedly a later mineral but has a lower structural complexity (IG, total) of 474.24 bits/cell, compared to sampleite, which has a complexity of 933.32 bits/cell.

An entry from the Inorganic Crystal Structure Database, the world’s repository for inorganic crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the joint CCDC and FIZ Karlsruhe Access Structures service and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Inorganic Crystal Structure Database, the world’s repository for inorganic crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the joint CCDC and FIZ Karlsruhe Access Structures service and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Flexible crystal() structures, which exhibit() single-crystal()-to-single-crystal() (SCSC) transformations(), are attracting attention() in many applied aspects: magnetic() switches, catalysis, ferroelectrics and sorption. Acid treatment() for titanosilicate material() AM-4 and natural() compounds with the same structures led to SCSC transformation() by loss() Na+, Li+ and Zn2+ cations with large structural() changes (20% of the unit()-cell() volume()). The conservation() of crystallinity through complex() transformation() is possible due() to the formation() of a strong hydrogen bonding() system(). The mechanism() of transformation() has been characterized using single-crystal() X-ray() diffraction analysis(), powder() diffraction, Rietvield refinement, Raman spectroscopy and electron microscopy. The low migration() energy() of cations in the considered materials() is confirmed using bond()-valence and density() functional() theory() calculations, and the ion conductivity of the AM-4 family's materials() has been experimentally verified.

The article provides a crystal chemical description of the second find of the P21/n modification of NaCaCu5(PO4)4Cl∙5H2O sampleite found at the Kester tin ore deposit. The mineral formation is genetically related to low-temperature oxidation processes of primary copper, zinc, and tin sulfides as well as to the formation of later Cu-, Zn-phosphates such as batagayite, epifanovite and sergeysmirnovite. The positions of hydrogen atoms in the structure of sampleite have been calculated with the DFT-method. The comparison of the real and theoretical IR spectra was carried out as an assessment of the reliability of the theoretical calculations. Sampleite was formed at the stage of hydrothermal alteration of Sn, Cu and Zn sulfide minerals and co-exists with epifanovite NaCaCu5(PO4)4[AsO2(OH)2]∙7H2O, which is undoubtedly a later one, but has a lower complexity (IG,total), 474.24 than sampleite 933.32 (bit/cel).

Abstract The crystal structure of nikmelnikovite, Ca12Fe2+Fe3+3Al3(SiO4)6(OH)20, a new member of the garnet supergroup from Kovdor massif, Kola Peninsula, Russia (R$\bar{3}$, a = 17.2072(6), c = 10.5689(4) Å, V = 2710.1(2) Å3 and Z = 3) has been refined to R1 = 0.046 on the basis of 1184 unique observed reflections. Nikmelnikovite is the first mineral species in the garnet supergroup that has a trigonal (rhombohedral) symmetry. The relationship between its unit cell and the pseudocubic (ideal garnet) unit cell can be described by the transformation matrix [1$\bar{1}$0 | 01$\bar{1}$ | ½½½]. The crystal-chemical relations between the ideal Ia$\bar{3}$d garnet and the nikmelnikovite structure type can be described by the following series of imaginary modifications: (1) the symmetry is lowered according to the Ia$\bar{3}$d → R$\bar{3}$ group–subgroup relationship; (2) the cation sites are split according to the following sequences: X → {X1, X2}; Y → {Y1, Y2, Y3, Y4}; Z → {Z1, Z2}; (3) the X sites remain fully occupied by Ca; (4) each Y site is occupied predominantly by a distinct chemical species: Y1 → Al (Al site), Y2 → Fe2+ (Fe1 site), Y3 → Fe3+ (Fe2 site), Y4 → vacancy (Mn site); (5) one of the Z sites (Z1) is occupied by Si, whereas the other site (Z2) is predominantly vacant. The crystal-chemical formula that takes into account the transition between the archetype and the nikmelnikovite structure type can be described as X{Ca12}Y[Fe2+Al4Fe3+2□]Z(Si6□6)O24(OH)20□4. The structural complexity of nikmelnikovite (4.529 bit/atom and 434.431 bit/cell, after H-correction) is higher than those for andradite, grossular and katoite, which is typical for low-temperature minerals formed after primary minerals with simpler structures.

Layered microporous titanosilicate AM-4 (Aveiro-Manchester-4) is a synthetic analog of microporous lintisite-type minerals. We applied the hydrothermal method to synthesize AM-4 compound from different titanium sources, i.e. titanium (III) chloride solution, titanyl-sulfate (titanite ore treatment product) and sodium metasilicate by stepwise cooling of an initial titanium-silicate mixture. In acid solution the crystal structure of AM-4 transformed into a novel layered titanosilicate SL3 (synthetic decationated lintisite) with a unique topology that consists of Ti2Si4O10(OH)4 nano-blocks. It was found that SL3 compound had a tendency for uptake of Ag from the standard test copper-nickel electrolyte. A possibility of repeated use of SL3 as a renewable sorbent was shown on the example of sorption Ca2+ cations. Both AM-4 and SL3 compounds can be considered as new functional materials of renewable and thermally stable nature with potential application for sorption and immobilization of the radioactive iodine isotopes.

The Kovdor massif is a part of the Paleozoic Kola alkaline province and located in the eastern part of the Baltic Shield. Kovdor carbonatites host a unique complex baddeleyite-apatite-magnetite deposit from which iron ores and zirconium have been mined. New data on melt inclusions in olivine crystals from phoscorites and olivinites of the ore complex are presented in this contribution. Daughter minerals in crystallized melt inclusions were identified by Raman spectroscopy and scanning electron microscopy. The trace element composition of inclusions was determined using LA-ICP-MS. Melt inclusions in olivine from Kovdor phoscorites are negative crystal or round in shape, with sizes ranging from 5 to 50 microns. They form groups or line up. According to the mineral composition, two types of melt inclusions can be distinguished: carbonate and silicate-carbonate. In the first type, Ca-Na-Mg- (Sr?) - REE carbonates are dominant among daughter phases. In the second one, silicate phases (phlogopite, monticellite, diopside), Ca-Na-Mg carbonates and magnetite are found together. Melt inclusions in olivine from olivinites are isometric or elongated, 5–25 μm in size. They form groups or occur as isolated inclusions. Benstoneite, geylussit, ankerite, calcite and hydroxyl-bastnesite along with phyllosilicates (phlogopite, paragonite?) were identified among daughter minerals. The rare earth elements composition of melt inclusions from both types of rocks is characterized by the predominance of light REE. The content of REE, especially light ones, in inclusions from phoscorites is higher. Strontium and barium contents in most melt inclusions have negative correlations with niobium and zirconium concentrations. Melt inclusions from phoscorites and olivinites contain carbonate and silicate mineral phases in various proportions, which may imply heterogeneous trapping of crystalline phases and two immiscible melts, silicate and carbonatite. Inclusions from phoscorite represent a more evolved magma with higher concentrations of rare metals. This work was supported by the Russian Science Foundation, grant No 19-17-00013.

The Kola rare-earth metallogenic province is the biggest in Russia.The largest resources of rare earth elements (REE) are confined to the Khibiny apatite deposits and loparite and eudialyte deposits of the Lovozero massif.In order to compare the prospects of different Kola deposits and occurrences, we estimated the value of rare-earth oxides contained in ores pursuant to average market prices of certain rare-earth oxides.Heavy REE (Dy, Yb, Tm, Tb, Lu) and Nd make the largest contribution to the value of REE-bearing ores despite the fact that light REE (La and Ce) make up the majority of the REE resources of almost all deposits in the region.Given mineral processing technologies and infrastructure available, we have identified the most important objectives to advance the REE industry in the region: (1) REE recovery from the currently produced minerals, namely, apatite of the Khibiny deposits and baddeleyite of the Kovdor deposit-high-level processing of the Kovdor baddeleyite concentrate can make Russia a dominant player on scandium market; (2) launching mining operations in the multicomponent (Ti-Ta-Nb)-REE-Zr Lovozero eudialyte deposit (in the first place, the Alluaiv site); (3) revaluation of the Afrikanda deposit in the light of new technologies for processing perovskite-titanomagnetite ores, as well as due to the fact that Russia currently lacks domestic production of titanium raw materials; (4) prospecting and exploration of the Keivy occurrences in alkaline granites and pegmatites and the development of processing technologies for these complex ores.

Manaevite-(Ce), a new vesuvianite-group mineral has been investigated by means of electron microprobe, TGA and DSC and CHN analysis of H2O, powder X-ray diffraction, single-crystal X-ray structure analysis, 139La NMR, 57Fe Mössbauer spectroscopy, IR spectroscopy and optical measurements. Tetragonal unit-cell parameters are a = 15.9247(13) Å, c = 11.9661(10) Å, space group P4/nnc. The structure model was solved and refined to R1 = 3.35% for 1757 independent observed reflections with I > 4σ(I). Manaevite-(Ce) is the first vesuvianite-group mineral with the species-defining role of REE3+ at the X3 site. The mineral contains two different kinds of hydroxyl anions. The first type of hydroxyl groups is associated with the O10 and O11 sites as observed for other vesuvianite-group members. Another type of OH groups is due to the hydrogarnet substitution (H4O4)4‒ ↔ (SiO4) 4‒ associated with the Z1 and Z2 sites. The incorporation of REE3+ into the crystal structure of manaevite-(Ce) proceeds via the substitution schemes 2Ca2+  ↔ Th4+ + □ and 3Ca2+  ↔ 2REE3+ + □, which results in the formation of vacancies at the X3 site and the presence of H2O molecules.

The modal composition of (apatite)-nepheline-titanite ore and its geological setting within apatite deposits of the Khibiny Massif allow selective mining of titanite ore and its hydrochloric acidic processing. The reaction of titanite with concentrated hydrochloric acid produces hydrated titanosilicate precipitate (TSP) which, in turn, can be a precursor in titanosilicate synthesis. It is particularly noteworthy that a synthetic analogue of korobitsynite, Na5(Ti3Nb)[Si4O12]2O2(OH)2·7H2O, was synthesized by means of TSP alteration by alkaline hydrothermal solution at 200 °C within three days. The titanosilicate obtained this way has comparatively weak cation-exchange properties regarding Cs+ and Sr2+ cations and considerable photocatalytic activity occurring under visible light, which allows the use of a synthetic korobitsynite analogue (SKR) for production of self-cleaning, sterilizing, and anti-fouling building materials.

Nikmelnikovite, Ca12Fe2+Fe\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{3}^{{3 + }}$$\end{document}Al3(SiO4)6(OH)20, a new mineral from the Kovdor massif (Kola Peninsula, Russia), is described. It is the first trigonal representative of the garnet supergroup. The mineral is named in honor of Academician Nikolai Nikolaevich Melnikov (1938–2018), an outstanding Soviet and Russia mining engineer, long-time (1981–2015) director of the Mining Institute of the Kola Science Center, Russian Academy of Sciences.

The present work contributes to the essential questions on calcium oxalate formation under the influence of lithobiont community organisms. We have discovered calcium oxalates in lichen thalli on surfaces of apatite-nepheline rocks of southeastern and southwestern titanite-apatite ore fields of the Khibiny peralkaline massif (Kola Peninsula, NW Russia) for the first time; investigated biofilm calcium oxalates with different methods (X-ray powder diffraction, scanning electron microscopy, and EDX analysis) and discussed morphogenetic patterns of its formation using results of model experiments. The influence of inorganic and organic components of the crystallization medium on the phase composition and morphology of oxalates has been analyzed. It was shown that, among the complex of factors controlling the patterns of biogenic oxalate formation, one of the main roles belongs to the metabolic activity of the lithobiont community organisms, which differs significantly from the activity of its individuals.

Chirvinskyite, (Na,Ca)13(Fe,Mn,□)2(Ti,Nb)2(Zr,Ti)3(Si2O7)4(OH,O,F)12, is a new wöhlerite–related zirconotitano–sorosilicate. It is triclinic, P 1 ¯ , a = 7.0477(5), b = 9.8725(5), c = 12.2204(9) Å, α = 77.995(5), β = 82.057(6), γ = 89.988(5)°, V = 823.35(9) Å3, Z = 1. The mineral was found in albitized alkaline pegmatites in a foyaite of the Mt. Takhtarvumchorr (Khibiny alkaline massif, Kola Peninsula, Russia, N 67°40′, E 33°33′). Chirvinskyite forms sheaf–like and radiated aggregates (up to 6 mm in diameter) of split fibrous crystals hosted by saccharoidal fluorapatite and albite. The mineral is pale cream in color, with a silky luster and a white streak. The cleavage is not recognized. Mohs hardness is 5. Chirvinskyite is biaxial (–), α 1.670(2), β 1.690(2), γ 1.705(2) (589 nm), 2Vcalc = 80.9°. The calculated and measured densities are 3.41 and 3.07(2) g·cm−3, respectively. The empirical formula based on Si = 8 apfu is (Na9.81Ca3.28K0.01)∑13.10(Fe0.72Mn0.69□0.54Mg0.05)∑2.00 (Ti1.81Nb0.19)∑2.00(Zr2.27Ti0.63)∑2.90(Si2O7)4{(OH)5.94O3.09F2.97}∑12.00. Chirvinskyite belongs to a new structure type of minerals and inorganic compounds and is related to the wöhlerite-group minerals. Its modular “wallpaper” structure consists of disilicate groups Si2O7 and three types of “octahedral walls”. The mineral is named in honor of Petr Nikolaevich Chirvinsky (1880–1955), Russian geologist and petrographer, head of the Petrography Department of the Perm’ State University (1943–1953), for his contributions to mineralogy and petrology, including studies of the Khibiny alkaline massif.

The Lovozero Alkaline Massif intruded through the Archaean granite-gneiss and Devonian volcaniclastic rocks about 360 million years ago, and formed a large (20 × 30 km) laccolith-type body, rhythmically layered in its lower part (the Layered Complex) and indistinctly layered and enriched in eudialyte-group minerals in its upper part (the Eudialyte Complex). The Eudialyte Complex is composed of two groups of rocks. Among the hypersolvus meso-melanocratic alkaline rocks (mainly malignite, as well as shonkinite, melteigite, and ijolite enriched with the eudialyte-group minerals, EGM), there are lenses of subsolvus leucocratic rocks (foyaite, fine-grained nepheline syenite, urtite with phosphorus mineralization, and primary lovozerite-group minerals). Leucocratic rocks were formed in the process of the fractional crystallization of melanocratic melt enriched in Fe, high field strength elements (HFSE), and halogens. The fractionation of the melanocratic melt proceeded in the direction of an enrichment in nepheline and a decrease in the aegirine content. A similar fractionation path occurs in the Na2O-Al2O3-Fe2O3-SiO2 system, where the melt of the “ijolite” type (approximately 50% of aegirine) evolves towards “phonolitic eutectic” (approximately 10% of aegirine). The temperature of the crystallization of subsolvus leucocratic rocks was about 550 °C. Hypersolvus meso-melanocratic rocks were formed at temperatures of 700–350 °C, with a gradual transition from an almost anhydrous HFSE-Fe-Cl/F-rich alkaline melt to a Na(Cl, F)-rich water solution. Devonian volcaniclastic rocks underwent metasomatic treatment of varying intensity and survived in the Eudialyte Complex, some remaining unchanged and some turning into nepheline syenites. In these rocks, there are signs of a gradual increase in the intensity of alkaline metasomatism, including a wide variety of zirconium phases. The relatively high fugacity of fluorine favored an early formation of zircon in apo-basalt metasomatites. The ensuing crystallization of aegirine in the metasomatites led to an increase in alkali content relative to silicon and parakeldyshite formation. After that, EGM was formed, under the influence of Ca-rich solutions produced by basalt fenitization.

This paper reviews the available information on the beryllium mineralogy of the different type of occurrences in the Kola Peninsula, northwest Russia. Beryllium mineralization in the region is mainly associated with alkaline and felsic rocks, which differ significantly in petrological, geochemical, mineralogical features and age. In total 28 beryllium minerals are established on the Kola Peninsula up today. Beryl is one of the ore minerals in the differentiated granite pegmatites of the Kolmozerskoe lithium deposit. A large diversity of beryllium minerals occur in the pegmatites and hydrothermal veins formed in the late stages of the Lovozero and Khibiny alkaline massifs. Most of these minerals, as leifite, lovdarite, odintsovite, sphaerobertrandite and tugtupite are rare in other environments and have unique properties. These minerals formed under conditions of extreme alkalinity and their formation was favored by abrupt changes in the alkalinity regimes. Some of minerals, as chrysoberyl in xenoliths of hornfels, genthelvite and unique intergrowth of meliphanite and leucophanite formed in contrasting geochemical fronts between felsic/intermediate and mafic rocks.

Nikmelnikovite, Ca12Fe2+Fe3+3Al3(SiO4)6(OH)20, is a new mineral from the Kovdor massif, Kola peninsula, Russian Federation. It is the first trigonal member of the garnet supergroup. The mineral is named in honor of Academician Nikolay Nikolaevich Melnikov (1938-2018), an outstanding Soviet and Russian mining engineer, long-time (1981-2015) director of the Mining Institute of the Kola Science Center, Russian Academy of Sciences.

Nikmelnikovite, Ca 12 Fe 2+ Fe _3^3 + Al 3 (SiO 4 ) 6 (OH) 20 , a new mineral from the Kovdor massif (Kola Peninsula, Russia), is described. It is the first trigonal representative of the garnet supergroup. The mineral is named in honor of Academician Nikolai Nikolaevich Melnikov (1938–2018), an outstanding Soviet and Russia mining engineer, long-time (1981–2015) director of the Mining Institute of the Kola Science Center, Russian Academy of Sciences.

Nikmelnikovite, Ca12Fe2+Fe Al3(SiO4)6(OH)20, a new mineral from the Kovdor massif (Kola Peninsula, Russia), is described. It is the first trigonal representative of the garnet supergroup. The mineral is named in honor of Academician Nikolai Nikolaevich Melnikov (1938-2018), an outstanding Soviet and Russia mining engineer, long-time (1981-2015) director of the Mining Institute of the Kola Science Center, Russian Academy of Sciences.

Geological setting and mineral composition of (apatite)-nepheline-titanite ore from the Khibiny massif enable selective mining of titanite ore, and its processing with sulfuric-acid method, without preliminary concentration in flotation cells. In this process flow diagram, titanite losses are reduced by an order of magnitude in comparison with a conventional flotation technology. Further, dissolution of titanite in concentrated sulfuric acid produces titanyl sulfate, which, in turn, is a precursor for titanosilicate synthesis. In particular, synthetic analogues of the ivanyukite group minerals, SIV, was synthesized with hydrothermal method from the composition based on titanyl-sulfate, and assayed as a selective cation-exchanger for Cs and Sr.