The crystal-chemical, vibrational, and optical properties of microporous aluminosilicate cancrinite have been investigated by combining electron probe microanalysis, single-crystal X-ray diffraction, infrared (IR) absorption, Raman, UV-Visible absorption, and electron spin resonance spectroscopy. The behavior of the peaks in the IR spectra was also studied during the dehydration of the sample. The analyzed sample has the following unit cell parameters (P6₃): a = 12.63189(14) Å, c = 5.13601(7) Å. The empirical formula, based on 12(Si + Al), is Na_6.47Ca_1.23K_0.01[Al_5.97Si_6.03O₂₄] (CO₃)_1.45(SO₄)_0.03Cl_0.01·2H₂O. The Al-Si framework of AB-type is formed by columns of based-shared “cancrinite” (CAN) cages, containing Na and H₂O positions located on the 3-fold axis, and channels with CO₃ groups, lying in two mutually exclusive and partially occupied positions in the center of the channel, and split Na/Ca cation sites. The revealed characteristics are somewhat different in comparison with the cancrinite structural features previously described in the literature. Studied crystals change color from grayish-pink to blue after X-ray irradiation (10⁴ Gy). The blue color of the irradiated cancrinite is caused by the formation (CO₃)^−● radicals in the crystals. Combining the results obtained using the selected methods will provide a better understanding of the relationships between the structural, chemical, and optical-physical properties of microporous aluminosilicates.

Fedorite is a rare phyllosilicate, having a crystal structure characterized by SiO₄-tetrahedral double layers located between continuous layers formed by edge-sharing (Ca,Na)-octahedra, and containing interlayer K, Na atoms and H₂O molecules. A mineralogical-petrographic and detailed crystal-chemical study of fedorite specimens from three districts of the Murun alkaline complex was performed. The sequence of the crystallization of minerals in association with fedorite was established. The studied fedorite samples differ in the content of interlayer potassium and water molecules. A comparative analysis based on polyhedral characteristics and deformation parameters was carried out. For the first time, EPR, optical absorption and emission spectra were obtained for fedorite. The raspberry-red coloration of the mineral specimens could be attributed to the presence of Mn⁴⁺ ions.

—Sulfur-containing sodalite, hackmanite, has been found for the first time in alkaline pegmatites of the Inagli alkaline–ultramafic massif, South Yakutia, Russia. Pegmatites with hackmanite have an amphibole–orthoclase (±diopside) and microcline–albite–amphibole (±aegirine) composition. The chemical composition of hackmanite (electron microprobe, wt %) is 25.60 Na₂O, 31.56 Al₂O₃, 37.20 SiO₂, 7.32 Cl, 0.57 S, 0.09 K₂O, 0.03 CaO, 0.04 FeO. The empirical formula, calculated on the basis of 12 (Si + Al) cations is, Na_8.07K_0.02\({\text{Fe}}_{{{\text{0}}{\text{.01}}}}^{{{\text{2 + }}}}\)(Al_5.96Si_6.04)_{Σ = 12}O_24.09(Cl_1.65S_0.17)_Σ = 1.82. The optical absorption, luminescence, and excitation spectra of the mineral revealed the presence of \({\text{O}}_{2}^{ - }\) and \({\text{S}}_{2}^{ - }\) sites. The EPR spectrum indicates the absence of a vacancy charge balance mechanism in the studied hackmanite sample. Thus, additional anions in hackmanite of the Inagli massif are Cl^– and \({\text{S}}_{2}^{ - }\) with an S–S bond length of 2.06 Å. According to the structure data, hackmanite does not contain S^2–, \({\text{S}}_{2}^{{2 - }}\), and (SO₄)^2– anions.

The Oktyabrsk PGE-Cu-Ni deposit is one of the largest resources in the Norilsk–Talnakh ore district, Russia, and it is viewed as an ore giant on a global scale. It contains three types of ores: massive, disseminated and veinlet-disseminated. The two former ore types were formed by a liquation process, whereas the latter was associated with fluid-induced selective metasomatic replacement of metamorphosed wall rocks. One of the major ore minerals in all ore types is chalcopyrite. In this study, we determined concentrations of trace elements in this mineral using laser ablation inductively coupled plasma mass spectrometry. It appeared that standard geochemical tools, such as plotting the data in the form of diagrams of normalized concentrations, binary and ternary plots, do not allow one to distinguish chalcopyrite from visually and genetically different ore types. In contrast, more advanced statistical methods such as cluster analysis show different groupings of elements for each ore type. Based on the element clustering, a classification tree was suggested, which allowed for the differentiation of massive, disseminated and veinlet-disseminated ore types of the Oktyabrsk deposit by Se, Te, Cd and Pb concentrations in chalcopyrite with a success rate of 86%. The general feature is that chalcopyrite of veinlet-disseminated ore is poorer in these elements compared to chalcopyrite of the two other ore types. Chalcopyrite of massive ore is poorer in Se and Te when compared to chalcopyrite of disseminated ore.

The minerals of carletonite group, fluorcarletonite, KNa₄Ca₄[Si₈O₁₈](CO₃)₄(F,OH)·H₂O and carletonite, Na₄Ca₄[Si₈O₁₈](CO₃)₄(OH,F)·H₂O, were investigated using a multi-method approach. A detailed comparative chemical study of the minerals was carried out using electron probe microanalysis and Fourier transform infrared spectroscopy. Using X-ray techniques and the results obtained, geometrical and distortion characteristics of the mineral structures are calculated and the successful crystal-structure refinement of these two natural compounds are given. Using spectroscopic and luminescence methods and ab initio calculations, it is shown that hole defects (CO₃)^•– are responsible for the colouration of the samples studied. Luminescence due to 5d–4f transition in Ce³⁺ ions is observed in both investigated compounds. Moreover, luminescence attributed to intrinsic luminescence, corresponding to the decay of electronic excitations of (CO₃)^2– complexes in the carletonite sample, is registered for the first time in phyllosilicates. An analysis of the optical absorption spectra and g-tensor values suggests that (CO₃)^•– defects in the crystal structure are localised in the C1 positions. Identification of these specific properties for these sheet silicates, with a two-dimensional infinite tetrahedral polymerisation, indicates that carletonites could be prospective materials for novel phosphors and luminophores.

In this work we report on a petrographic, crystal-chemical, and optical characterization, obtained from different analytical methods, of amphibole species. Potassic-hastingsite, ideally ^AK^BCa₂^C(Fe²⁺₄Fe³⁺)^T(Si₆Al₂)O₂₂^W(OH)₂, has been found in the Kedrovy district (East Siberia, Russia). The sample occurs as well-formed and large radially radiant aggregates of dark green, almost black crystals. The unit cell dimensions are a = 9.9724(3) Å, b = 18.2968(4) Å, c = 5.3573(1) Å, β = 104.945(3)°, V = 944.44(4) ų, Z = 2. Site populations were determined by combining single-crystal structure refinement and electron probe microanalysis, and Fe³⁺/Fe²⁺ ratio was obtained from X-ray fluorescence analysis. Infrared, diffuse light UV/Vis/NIR absorption, and electron spin resonance spectra are presented and discussed. A thermoelastic behavior of a powder of potassic-hastingsite was studied by in situ high-temperature X-ray diffraction. A thermal expansion and subsequent significant contraction in the unit cell volume during a high-temperature X-ray powder diffraction experiment is observed as a consequence of the deprotonation process, which is locally balanced via oxidation of Fe²⁺. According to the data obtained for potassic-hastingsite, these processes occur within 400–600 °C. The thermal expansion of the mineral is anisotropic; the thermal expansivity coefficients α_a:α_b:α_c (×10⁻⁶) = −18.06:9.59:−1.09 at 400 °C, −26.15:−1.52:2.22 at 600 °C and 23.77:−25.06:42.08 at 750 °C.