International Mineralogical Association Research Articles

SOME CHARACTERISTICS AND CAUSES OF CHANGES IN THE RATE OF DISCOVERY OF NEW MINERALS SINCE 1800

ABSTRACT Construction of a discovery curve for Earth's minerals illustrates an abrupt inflection in rates of discovery and acceptance of new species that occurred in the middle of the 20th century. Prior to that time new mineral discovery is found to have accelerated at a modest pace of 0.3 species / year2. Since 1950 the rate of acceptance has accelerated at an average of 1.04 species / year2 such that the first two decades of the 21st century have been characterized by the acceptance of over 100 new minerals per year. Despite this rapid acceleration of discovery, the relative distribution among the 10 mineral classes of the Nickel-Strunz classification system of minerals identified prior to and after 1950 are nearly identical. Variation in the rates of attestation of the divisions, families, and mineral groups show distinct differences in that the maximum rates of discovery of minerals populating higher taxonomic levels occurred prior to 1950 while the attestation curve of newly recognized groups closely follows that defined by the identification of mineral species. The application of any hierarchical classification system to the mineral species is somewhat arbitrary and subject to biases or inconsistencies associated with the systematics of classification. Therefore, the discovery of new minerals is also considered within the context of the mathematically defined crystallographic space group symmetries. The space group attestation curve has a shape similar to those exhibited by the higher taxonomic levels within the Nickel-Strunz system. However, not all space groups are represented by naturally occurring minerals. Minerals discovered before and after the inflection in rates of new mineral discovery illustrate significantly different patterns of paragenesis. Nearly all of the species have been associated with one or more of 57 distinct paragenetic modes. Minerals that have long been known tend to have a higher number of paragenetic modes than those more recently discovered such that the average number of paragenetic modes is shown to have decreased linearly from 1950 to 2022. Further, the earliest known occurrence of over 80% of the currently accepted mineral species has been tabulated by the International Mineralogical Association. For species discovered prior to the inflection of 1950 a linear distribution of oldest ages is observed indicating that these minerals have earliest ages of occurrence that are uniformly distributed across the interval 0 to 4700 Ma. Conversely, approximately 70% of the species identified since 1950 have oldest known occurrences of less than 600 Ma and the age distribution of these post-1950 minerals exhibit an exponential distribution suggesting increasing efforts in new mineral discovery in tectonically active settings. Despite the differences in the pre- and post-1950 oldest age distributions, both populations exhibit similar temporal excursions in rates of new mineral creation that likely reflect substantial changes in Earth system processes responsible for new mineral formation.

Major structural types in inorganic chemistry and mineralogy: New data

Research subject. Structural types with different stoichiometric correlations between chemical elements. Aim. To analyze the prevalence of structural types with different stoichiometric correlations between chemical elements, such as simple substances with binary compounds, triple compounds with stoichiometry ABX3, triple compounds with stoichiometry AB2X4. Key points. The analysis was conducted using the databases of inorganic compounds ICSD (Inorganic Crystal Structure Database) and PCD (Pearson’s Crystal Data). The number of entries with the most typical structural types for 2013 and 2023 are determined. Their classifications in various databases for different years are given. The ranks of structural types for minerals and inorganic compounds are analyzed. The minerals crystallized in all the considered structural types are indicated according to the 2023 ISCD data, sampling only by the number of minerals registered in IMA (International Mineralogical Association – Commission on New Minerals, Nomenclature and Classification) for March 2023. The Russian names of minerals are presented in accordance with the database WWW-MINCRIST for the minerals crystallizing in all the structural types under consideration. Conclusions. The most probable causes for the realization of each stoichiometric correlation in various structural types are determined. The prevalence of certain structural types among inorganic compounds and minerals, as well as the underlying reasons, are discussed based on the principles of crystal chemistry.

Three new iron-phosphate minerals from the El Ali iron meteorite, Somalia: Elaliite, Fe2+8Fe3+ (PO4)O8; elkinstantonite, Fe4(PO4)2O; and olsenite, KFe4(PO4)3

Abstract Petrologic investigation of the El Ali IAB iron meteorite (Somalia) revealed three new minerals: elaliite (Fe2+8Fe3+ (PO4)O8, IMA 2022-087), elkinstantonite(Fe4(PO4)2O, IMA 2022-088), and olsenite (KFe4(PO4)3, IMA 2022-100). The name elaliite recognizes the occurrence of this mineral within the El Ali meteorite, originally located at 4° 17′ 17″N, 44° 53′ 54″E. Elkinstantonite is named after Linda (Lindy) Elkins-Tanton (b. 1965), a planetary scientist and professor in the School of Earth and Space Exploration at Arizona State University. The name olsenite is in honor of Edward J. Olsen (1927-2020), the former Curator of Mineralogy and Meteorites at the Field Museum of Natural History in Chicago (1960-1991). The new minerals and their names have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association. The holotype specimens of elaliite, elkinstantonite and olsenite consist of the polished block mount with accession number MET11814/2-1/EP1 deposited in the University of Alberta Meteorite Collection. Elaliite, elkinstantonite and olsenite occur along with wustite, troilite, sarcopside and Ca-bearing graftonite within inclusions in the iron-nickel metal (kamacite, 9.4 wt% Ni) that makes up the bulk of the El Ali sample. The empirical formulas determined by electron probe microanalysis for elaliite, elkinstantonite, and olsenite are: (Fe2+7.943Fe3+1.020Cr0.010Ni0.006Ca0.004Mn0.004)Σ8.987(P0.932Si0.077S0.005)Σ1.014O12, (Fe2+3.947Mn0.016Ni0.003Ca0.001Cr0.001)Σ3.968(P1.986Si0.014S0.013)Σ2.013O9, and (K0.820Na0.135Ca0.004)Σ0.959(Fe3.829Mn0.050)Σ3.879(P2.972S0.058Si0.017)Σ3.047O12. Electron backscatter diffraction was used to confirm the crystal structures of the three new minerals. Raman spectra for all three minerals are also presented.

Wenlanzhangite–(Y) from the Yushui deposit, South China: a potential proxy for tracing the redox state of ore formation

Abstract Mineral phases in which vanadium (V) and heavy–rare–earth elements (HREEs) coexist are rarely documented. Here, we report a new V–HREE–bearing silicate mineral species, wenlanzhangite–(Y), which is a vanadiferous derivate of jingwenite–(Y) [Y2Al2V4+2(SiO4)2O4(OH)4] coexisting with jingwenite–(Y) in bedded/massive ores at Yushui, South China. Wenlanzhangite–(Y) forms as a dark brown, 70–100 μm–thick rim on a core domain of jingwenite–(Y), which occurs as 100–200 μm columnar crystals. The colour, streak, lustre, and hardness (Mohs) are dark brown, yellow grey, vitreous, and ~4, respectively. Compared to jingwenite–(Y), wenlanzhangite–(Y) has higher vanadium and lower aluminium contents. Calculated on the basis of 8 cations, the empirical formula is (Y1.26Dy0.17Er0.11Gd0.09Yb0.09Nd0.09Sm0.06Sc0.04Ho0.03Ce0.02Tb0.02Tm0.02Pr0.01)Σ2.00(V3+1.46Al0.54)Σ2.00V4+2(SiO4)2O4(OH)4, which can be simplified to the ideal formula Y2V3+2V4+2(SiO4)2O4(OH)4. Wenlanzhangite–(Y) is triclinic, with space group P–1(#2), Z = 2, and unit–cell parameters a = 5.9632(7) Å, b = 9.599(1) Å, c = 9.9170(9) Å, α = 90.033(8)°, β = 98.595(2)°, γ = 90.003(9)°, and V = 561.28(10) Å3. Wenlanzhangite–(Y) is approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification (IMA2022–142). The structure of wenlanzhangite–(Y) is composed of a–axis–oriented chains of [VO6] octahedra consisting of edge–sharing octahedra linked by insular [SiO4] tetrahedra, leaving open channels occupied by rare earth elements. Observed compositional variation and crystal structure demonstrate that V3+ can substitute for Al3+ in jingwenite–(Y), forming wenlanzhangite–(Y). The occurrence of wenlanzhangite–(Y) indicates a relatively more reducing hydrothermal environment causing reduction of V5+ in oxidized fluids to V3+ and thus represents a useful proxy for tracing the redox state of ore formation.

Testibiopalladite, PdSbTe: A Valid Mineral and Sb-Analogue of Michenerite

Abstract Testibiopalladite was reported from two unnamed deposits in China by Anonymous (1974) to be ideally PdSbTe. The description of the mineral included an indexed X-ray powder diffraction pattern, space group determination, electron probe micro-analyses, reflectance, and micro-indentation hardness measurements. This description was published without prior submission to the IMA, which was the norm at the time before China became a member. It is unknown as to why the Commission for New Minerals and Mineral Names (CMNMN) did not examine and vote on the mineral as had been done for all other Chinese mineral descriptions published at the time. It is surprising because the chairman of the CMNMN at the time had reviewed the mineral (Fleischer et al. 1976) and concluded it was a valid species, i.e., the Sb analogue of michenerite (PdBiTe). Further, the same article included a description of “hexastibiopanickelite” which was voted on and rejected by the CMNMN in 1976. From 1981 to 2021 there were many papers published reporting testibiopalladite from several deposits in different countries (e.g., Hudson et al. 1978, Chen et al., 1993, Stepanets et al. 2019, 2020), as well as a single-crystal structure analysis of synthetic PdSbTe which confirmed the assigned space group (Foecker & Jeitschko 2001). The published data (e.g., Barkov et al. 2002, Liang et al. 2019, 2023) suggest that testibiopalladite is a valid mineral species, ideally PdSbTe, and is the Sb analogue of michenerite, PdBiTe, both crystallizing in space group P213. Both the name testibiopalladite and the mineral, ideally PdSbTe, were approved by the Commission of New Minerals, Nomenclature and Classification of the International Mineralogical Association (CNMNC-IMA), Nomenclature Voting Proposal 23-H. Liang et al. (2019, 2023) studied samples from the type locality (Yangliuping deposit, PRC) that are to be considered as a neotype.

TiO2 II: The high‐pressure Zr‐free srilankite endmember in impact rocks

AbstractTiO2II, a high‐pressure polymorph of titanium dioxide, is a diagnostic indicator of shock metamorphism in impact rocks. Due to its typical micro‐to‐nanometer scale, there are no ab initio structure solutions of natural TiO2II, thereby generating uncertainty about its crystal structure and its known similarity with srilankite (Ti0.67,Zr0.33)O2. Nanoscale electron diffraction investigation of TiO2II from the Australasian tektite strewn field provides the first ab initio structure solution revealing a primitive orthorhombic lattice with cell parameters a = 4.547 Å, b = 5.481 Å, c = 4.891 Å, and space group Pbcn, that is, the same as srilankite and scrutinyite α‐PbO2. The linear a and c decrease, and b increase with Ti content indicate TiO2II as Zr‐free srilankite endmember in the binary system ZrO2‐TiO2. Thereby the name srilankite should be used referring to TiO2II, according to the International Mineralogical Association recommendations. We provide the first evidence for a topotactic subsolidus rutile‐to‐TiO2II transition, founding their finely intermixing nanocrystals in the same TiO2 crystal, where TiO2II is within the crystal and surrounded by rutile in direct contact. They also show recurrent iso‐orientation, with TiO2II [100] parallel to rutile [100], TiO2II [010] parallel to rutile [011], and TiO2II [001] parallel to rutile (0–11). The rutile‐TiO2II iso‐orientation suggests the compression of rutile (0–11) planes as a possible transition mechanism from rutile to TiO2II, with a consequent shortening of ~0.5 Å per cell. The presence of TiO2II in the distal (~1200 km) impact ejecta from the Australasian tektite strewn field indicates shock pressures of ~12–15 GPa and post‐shock temperatures below 500°C followed by rapid quenching.

Arsenoústalečite, Cu12(As2Te2)Se13, a new mineral, and crystal structures of arsenoústalečite and stibioústalečite

AbstractArsenoústalečite is a new mineral discovered in a sample collected from the abandoned Ústaleč deposit near Horažďovice, SW Bohemia, Czech Republic. It occurs as rare anhedral grains, up to 40 μm in size, in a calcite gangue, associated with stibioústalečite, hakite-(Hg), berzelianite and uraninite. Arsenoústalečite is dark grey, with a metallic lustre. Mohs hardness is ca. 3½–4; calculated density is 5.730 g/cm3. In reflected light, arsenoústalečite is pale grey with a yellowish shade; it is isotropic. Internal reflections were not observed. Reflectance values for the four COM wavelengths in air [R (%) λ (nm)] are: 33.3 (470); 33.1 (546); 33.0 (589); and 32.9 (650). The empirical formula of arsenoústalečite is (Cu5.81Ag0.17)Σ5.98(Cu5.95Fe0.02Zn0.02Hg0.01)Σ6.00(As1.40Sb0.87Te1.73)Σ4.00(Se10.30S2.32)Σ12.61. The ideal formula is Cu12(As2Te2)Se13, which requires (in wt.%) Cu 34.76, As 6.83, Te 11.63, Se 46.78, total 100.00. Arsenoústalečite is cubic, I$\bar{4}$3m, with unit-cell parameters a = 10.6580(19) Å, V = 1210.7(6) Å3 and Z = 2. The strongest reflections of the calculated powder X-ray diffraction pattern [d, Å (I, %) hkl] are: 3.077 (100) 222, 2.848 (10) 321, 1.946 (12) 521, 1.884(52) 440 and 1.608(21) 622. According to the single-crystal X-ray diffraction data (R1 = 0.0285 on the basis of 334 unique reflections with Fo > 4σFo and 24 refined parameters), arsenoústalečite is isotypic with other tetrahedrite-group minerals. The crystal structure of co-existing stibioústalečite, with an empirical formula of (Cu5.69Ag0.07)Σ5.76(Cu5.80Zn0.13Fe0.06Hg0.01)Σ6.00(Sb1.82As0.42Te1.76)Σ4.00(Se9.52S3.10)Σ12.62 and unit-cell parameters a = 10.6975(16) Å, V = 1224.2(5) Å3 and Z = 2, was refined to R1 = 0.0191 on the basis of 267 unique reflections with Fo > 4σFo and 24 refined parameters. Structural relationships and crystal-chemistry of both members of the ústalečite series are discussed. Arsenoústalečite is named after its type locality, the Ústaleč deposit and its chemical composition. The mineral and its name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2022-116).

WinPclclas, a Windows Program for Pyrochlore Supergroup Minerals

Abstract A Microsoft® Visual Basic program, WinPclclas, has been developed to calculate the chemical formulae of pyrochlore supergroup minerals (PSM) based on data obtained from wet-chemical and electron-microprobe analyses. These are also classified following the nomenclature scheme adopted by the Commission on New Minerals, Nomenclature and Classification (CNMNC) of the International Mineralogical Association for PSM (IMA-10) and including both subsequent group and species updates. The program considers classification among the 33 IMA-approved PSM, as well as ten species that have not been approved, adhering to the general formula A2B2X6Y and considering the dominant ions at the A, B, and Y sites. It considers PSM represented by the pyrochlore, microlite, roméite, elsmoreite, and betafite groups, along with unassigned members of the ralstonite and coulsellite groups. Mineral formulae of the PSM are calculated based on the ideal number of B cations being two apfu, owing to the potential for vacancies at the A, X, and Y sites. WinPclclas operates in four stages: (1) it estimates cation and anion contents provided by input chemical data; (2) it determines the dominant cation and anion at the A, B, and Y sites; (3) it assigns the PSM to one of the seven groups, based on the dominant cation at the B site (i.e., W6+, Nb5+, Ta5+, Sb5+, Ti4+, Al3+, and Mg2+); and (4) it classifies the pyrochlore species into an appropriate group, based on the dominant cation at the A site and the dominant anion at the Y site. The H2O (wt.%) content for the PSM is estimated by stoichiometric constraints. WinPclclas allows users to: (1) enter up to 51 input variables for mineral-chemical analyses; (2) type and load multiple PSM compositions in the data entry section; (3) edit and load the Microsoft® Excel files used in calculating, classifying, and naming the PSM, together with the total monovalent to hexavalent cation, and (4) store all the calculated parameters in the output of a Microsoft® Excel file for further data evaluations. The program is distributed as a self-extracting setup file, including the necessary support files used by the program, a help file, and representative sample data files.

Fedor Ivanovich Rukavishnikov (1902–1942) and former rukavishnikovite (now ternesite)

Fedor Ivanovich Rukavishnikov is a major specialist in the field of mineralogy of the Urals. Author of the first Ural identification of minerals based on external characteristics. He worked at the Sverdlovsk Mining Institute from 1925 to 1937 and was successively an assistant, associate professor of the Department of Mineralogy, and also served as vice-rector and rector. In 1937 he went to Moscow to work at the Institute of Geological Sciences of the Academy of Sciences USSR. In 1941 he joined the Moscow militia, was captured and died in a concentration camp in 1942. A new mineral was named in honor of Fyodor Ivanovich – rukavishnikovite, which was discovered by B.V. Chesnokov in the burnt dumps of the Chelyabinsk coal basin. The International Mineralogical Association did not approve it as a new mineral species, and a few years later a natural analogue of rukavishnikovite, ternesite, was found in Germany

Crystal chemistry of type paulkerrite and establishment of the paulkerrite group nomenclature

Abstract. A single-crystal structure determination and refinement has been conducted for the type specimen of paulkerrite. The structure analysis showed that the mineral has monoclinic symmetry, space group P21/c, not orthorhombic, Pbca, as originally reported. The unit-cell parameters are a=10.569(2), b=20.590(4), c=12.413(2) Å, and β=90.33(3)∘. The results from the structure refinement were combined with electron microprobe analyses to establish the empirical structural formula A1[(H2O)0.98K0.02]Σ1.00 A2K1.00 M1(Mg1.02Mn0.982+)Σ2.00 M2(Fe1.203+Ti0.544+Al0.24Mg0.02)Σ2.00 M3(Ti0.744+ Fe0.263+)Σ1.00 (PO4)4.02 X[O1.21F0.47(OH)0.32]Σ2.00(H2O)10 ⋅ 3.95H2O, which leads to the end-member formula (H2O)KMg2Fe2Ti(PO4)4(OF)(H2O)10 ⋅ 4H2O. A proposal for a paulkerrite group, comprising orthorhombic members benyacarite, mantiennéite, pleysteinite, and hochleitnerite and monoclinic members paulkerrite and rewitzerite, has been approved by the International Mineralogical Association's Commission for New Minerals, Nomenclature and Classification. The general formulae are A2M12M22M3(PO4)4X2(H2O)10 ⋅ 4H2O and A1A2M12M22M3(PO4)4X2(H2O)10 ⋅ 4H2O for orthorhombic and monoclinic species, respectively, where A= K, H2O, □ (= vacancy); M1 = Mn2+, Mg, Fe2+, Zn (rarely Fe3+); M2 and M3 = Fe3+, Al, Ti4+ (and very rarely Mg); X= O, OH, F. In monoclinic species, K and H2O show an ordering at the A1 and A2 sites, whereas O, (OH), and F show a disordering over the two non-equivalent X1 and X2 sites, which were hence merged as X2 in the general formula. In both monoclinic and orthorhombic species, a high degree of mixing of Fe3+, Al, and Ti occurs at the M2 and M3 sites of paulkerrite group members, making it difficult to get unambiguous end-member formulae from the structural determination of the constituents at individual sites. To deal with this problem an approach has been used that involves merging the compositions at the M2 and M3 sites and applying the site-total-charge method. The merged-site approach allows end-member formulae to be obtained directly from the chemical analysis without the need to conduct crystal-structure refinements to obtain the individual site species.

Anisim Efremovich Malakhov (1899–1989) and former malakhovite (now khesinite)

Anisim Efremovich Malakhov, a prominent specialist in the fi eld of geology of ore, non-ore and rare metal deposits of the Urals. For about 30 years he headed the Department of Geology of Ore Deposits and Coal and Non-Metal Deposits of the Faculty of Exploration Geology at the Sverdlovsk Mining Institute. In honor of Anisim Efremovich, a new mineral was named – malakhovite, calcium, magnesium and iron silicate, which was discovered by B. V. Chesnokov in the burnt dumps of the Chelyabinsk coal basin. The International Mineralogical Association did not approve it as a new mineral species, and recently a natural analogue of malachovite, hesinite, was found in Israel.

Structural and Chemical Diversity and Complexity of Sulfur Minerals

The chemical and structural diversity of minerals containing sulfur as an essential mineral-forming element has been analyzed in terms of the concept of mineral systems and the information-based structural and chemical complexity parameters. The study employs data for 1118 sulfur mineral species approved by the International Mineralogical Association. All known sulfur minerals belong to nine mineral systems, with the number of essential components ranging from one to nine. The chemical and structural complexity of S minerals correlate with each other; that is, on average, chemical complexification results in structural complexification. The minerals with S–O bonds (sulfates and sulfites) are more complex than those without S–O bonds (sulfides and sulfosalts). However, the most complex sulfur mineral known so far is incomsartorite, Tl6Pb144As246S516, a sulfosalt. The complexity-generating mechanism in sulfides and sulfosalts is the complex combination of different modules excised from parent PbS or SnS archetypes with the subsequent formation of superstructures. The drivers for structural complexity in sulfates are more diverse and, in addition to modular construction and superstructures, also include a high hydration state, the presence of polyatomic clusters, and framework complexity. The most complex Martian minerals are most probably halotrichite-group minerals. The chemical and structural complexity increases with the passage of geological time with the formation of the most complex sulfosalts at Lengenbach (Swiss Alps) triggered by life (activity of sulfur-reducing bacteria).

Nomenclature of the triphylite group of minerals

Abstract. In this paper we present a Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA-CNMNC)-accepted scheme for the classification and nomenclature of the triphylite group of minerals. The general formula of those minerals is M1M2TO4, where M1 and M2 refer to cations in an octahedral coordination: M1 = □, Na, Li; M2 = Mn2+, Fe2+, Mg, Fe3+, Mn3+, and T to tetrahedrally coordinated P5+ cations. The group contains the Li-bearing phosphates triphylite [LiFe2+(PO4)] and lithiophilite [LiMn2+(PO4)] and their oxidation products heterosite [Fe3+(PO4)] and purpurite [Mn3+(PO4)], as well as the Na-bearing phosphates natrophilite [NaMn2+(PO4)] and karenwebberite [NaFe2+(PO4)]. The Li–Mg-bearing phosphate simferite has been redefined as LiMg(PO4). Ferrisicklerite and sicklerite correspond to intermediate phases in the triphylite–heterosite and lithiophilite–purpurite solid solutions; consequently, according to the CNMNC dominant-constituent rule, they are discredited. A new mineral oxidation sequence is defined, which considers the different oxidation capacity of iron and manganese, and therefore replaces the traditional Quensel–Mason sequence. The formula calculation procedure for Li-bearing species, based on electron microprobe analyses and single-crystal X-ray diffraction data, is also described.

Pavel Ivanovich Kutyukhin (1899–1962) and former kutyukhinite (now kumtyubeite)

Pavel Ivanovich Kutyukhin, a prominent specialist in geology and mineralogy of gold, rare metal and tungsten deposits of the Urals. For about 15 years he headed the departments of exploration and geology of ore deposits of the Geological Exploration Faculty at the Sverdlovsk Mining Institute. In honor of Pavel Ivanovich, a new mineral was named – kutyukhinite, calcium fluorosilicate, which was discovered by B. V. Chesnokov in the burnt dumps of the Chelyabinsk coal basin. The International Mineralogical Association did not approve it as a new mineral species, and recently a natural analogue, kumtyubeite, was found in the North Caucasus.

Vrančiceite, Cu10Hg3S8, a new Cu–Hg sulfide mineral from Vrančice, Czech Republic

AbstractVrančiceite is a new mineral species discovered in a sample collected from the old mine dumps of the abandoned Vrančice deposit near Příbram, central Bohemia, Czech Republic. Vrančiceite occurs as rare anhedral grains, up to 100 μm in size, in a calcite gangue, associated with cinnabar, djurleite, galena and hedyphane. Vrančiceite is black, with metallic lustre. Mohs hardness is ca. 2–3, calculated density is 6.652 g.cm–3. In reflected light, vrančiceite is light grey with a yellowish shade; bireflectance, pleochroism and anisotropy are all weak. Internal reflections were not observed. Reflectance values for the four Commission on Ore Mineralogy wavelengths of vrančiceite in air [Rmax, Rmin (%) (λ in nm)] are: 33.6, 31.2 (470); 33.9, 30.6 (546); 31.1, 30.0 (589); and 32.1, 29.1 (650). The empirical formula, based on electron-microprobe analyses, is Cu10.11(4)Ag0.01(1)Hg2.87(4)Sb0.01(1)Bi0.01(1)S7.99(8). The ideal formula is Cu10Hg3S8 (Z = 2), which requires (in wt.%) Cu 42.54, Hg 40.29 and S 17.17, total 100.00. Vrančiceite is triclinic, P$\bar{1}$, with unit-cell parameters a = 7.9681(2), b = 9.7452(3), c = 10.0710(3) Å, α = 77.759(1), β = 76.990(1), γ = 79.422(1)°, V = 737.01(4) Å3 and Z = 2. The strongest reflections of the calculated powder X-ray diffraction pattern [d, Å (I) hkl] are: 3.354 (76) $\bar{2}$01, 3.111 (68) 222, 2.833 (100) 213, 2.733 (93) 231, 2.705 (76) 2$\bar{2}$1 and 2.647 (71) $\bar{2}\bar{1}$2. According to the single-crystal X-ray diffraction data (R1 = 0.0262), the crystal structure of vrančiceite can be described as comprising Cu–S layers, connected through CuS3 polyhedra, giving rise to a three-dimensional framework with channels running along the a axis and hosting linearly coordinated Hg atoms. Structural relations with gortdrumite are discussed. Vrančiceite is named after its type locality, the Vrančice deposit near Příbram. The mineral and its name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2022–114).

Tennantite-(Ni), Cu6(Cu4Ni2)As4S13, from Luobusa ophiolite, Tibet, China: a new Ni member of the tetrahedrite group

AbstractThe new mineral tennantite-(Ni), Cu6(Cu4Ni2)As4S13, has been discovered from the Luobusa Chromitite, Tibet, southwestern China. Tennantite-(Ni) occurs as anhedral grains ranging from 2 to 20 μm in size. In reflected light microscopy, tennantite-(Ni) is isotropic and appears yellow-greenish grey. Reflectance data for Commission on Ore Mineralogy wavelengths in air for tennantite-(Ni) are: 31.0 (470 nm), 29.6 (546 nm), 29.6 (589 nm) and 29.3 (650 nm). Electron microprobe analysis for holotype material gave the empirical formula (on basis of total cations = 16 apfu): M(2)Cu6M(1)[Cu4.00(Ni0.97Cu0.53Fe0.50)Σ2.00]Σ6.00X(3)(As2.94Sb1.06)Σ4S12.77. Tennantite-(Ni) is cubic, with space group I$\bar{ 4}$3m (#217), a =10.2957(9) Å, V = 1091.4(3) Å3 and Z = 2. By using single-crystal X-ray diffraction, the crystal structure has been determined and refined to a final R1 = 0.0423 on the basis of 163 independent reflections [Fo > 4σ (Fo)]. The calculated seven strongest powder X-ray diffraction lines [d in Å (I) (hkl)] are: 2.972 (100) (222), 1.820 (83) (440), 2.574 (28) (400), 1.552 (18) (622), 3.640 (10) (220), 1.880 (10) (521) and 1.287 (7) (800). Tennantite-(Ni) is isostructural with other tetrahedrite-group minerals, and nickel is hosted at the tetrahedrally coordinated M(1) site, along with Cu and minor Fe. The mineral and its name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2021-018).

Holubite, Ag3Pb6(Sb8Bi3)Σ11S24, from Kutná Hora, Czech Republic, a new member of the andorite branch of the lillianite homologous series

AbstractA new mineral species, holubite, ideally Ag3Pb6(Sb8Bi3)Σ11S24, has been found at Kutná Hora ore district, Czech Republic. The mineral is associated with other lillianite homologues (gustavite, terrywallaceite, vikingite and treasurite) most frequently as grain aggregates and replacement rims of earlier Ag–Pb–Bi minerals, growing together in aggregates up to 200 × 50 μm. It typically occurs in a close association with Ag,Bi-bearing galena and terrywallaceite. Holubite is opaque, steel-grey in colour and has a metallic lustre, the calculated density is 5.899 g/cm3. In reflected light holubite is greyish white and bireflectance and pleochroism are weak with grey tints. Anisotropy is weak to medium with grey to bluish-grey rotation tints. Internal reflections were not observed. Electron microprobe analyses yielded an empirical formula, based on 44 atoms per formula unit (apfu) of (Ag3.03Cu0.03)Σ3.06(Pb6.19Fe0.02Cd0.01)Σ6.22(Sb7.71Bi2.90)Σ10.61S24.12. Its unit-cell parameters are: a = 19.374(4), b = 13.201(3), c = 8.651(2) Å, β = 90.112(18)°, V = 2212.5(9) Å3, space group P21/n and Z = 2. Holubite is a new member of the andorite branch of the lillianite homologous series with N = 4. The structure of holubite contains two Pb sites with a trigonal prismatic coordination, eight distinct octahedral sites, of which one is a mixed (Bi,Ag) site and one is a mixed (Sb,Pb) site, and twelve anion sites. Holubite is defined as a lillianite homologue with the three following requirements: N = 4, L% [Ag+ + (Bi3+,Sb3+) ↔ 2 Pb2+ substitution] ≈ 70% and approximately one quarter to one third at.% of antimony is replaced by bismuth [Bi/(Bi+Sb) ≈ 0.26–34]. The new mineral has been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2022-112) and named after Milan Holub, a key Czech geologist and specialist in the Kutná Hora ore district.

Andrieslombaardite, RhSbS, a new platinum-group mineral from the platiniferous Onverwacht Pipe, Republic of South Africa

Abstract A hundred years after the discovery of the Merensky Reef in 1924, it is appropriate to present the new mineral andrieslombaardite in honour of Andries Frederik Lombaard who was instrumental in its discovery. Andrieslombaardite, RhSbS, was first described as an unknown mineral from placer deposits associated with the Tulameen Alaskan-Uralian type complex, British Colombia, Canada (Raicevic and Cabri, 1976) but has since been reported from several other deposits including the platiniferous Driekop, Mooihoek, and Onverwacht pipes in the eastern Bushveld Complex, South Africa. The mineral and the name were approved by the Commission on New Minerals Nomenclature and Classification (CNMNC) of the International Mineralogical Association (IMA no. 2022-076) based on data in the co-type samples from Onverwacht and a co-type sample from the Yubdo stream, Birbir River, Ethiopia. Andrieslombaardite in the Onverwacht sample is a single 8 x 20 μm grain attached to laurite in a matrix of altered silicate and Fe-oxyhydroxide minerals. In the Yubdo samples, there are many grains of pale brownish gray andrieslombaardite up to 25 x 55 μm in size, included in Pt-Fe alloys, some associated with erlichmanite, and others attached to bornite and chalcopyrite. The reflectance values (R%) measured in air and in oil at the COM wavelengths are 48.3 and 33.0 (470 nm), 49.3 and 34.0 (546 nm), 51.0 and 35.9 (589 nm), and 51.8 and 36.7 (650 nm). The colour values x, y, Y, λd, and Pe in air are 0.317, 0.322, 50.3, 580, and 3.2, and in oil are 0.319, 0.324, 35.6, 579, and 4.5. The composition of andrieslombaardite is ideally RhSbS, but it contains variable amounts of Fe, Pt, Pd, and Ir that may substitute for Rh. The mineral is cubic with unit-cell dimensions of a = 6.0278(4) Å, V = 219.01(6) Å3 and Z = 4. It was synthesised at 400 and 550°C using stoichiometric elemental amounts. It is a member of the cobaltite group. The mineralisation of the intrusive dunite pipes was probably introduced at high temperatures, under magmatic conditions. The primary assemblages were to a certain degree overprinted and redistributed by low-temperature hydrothermal fluids. The Pt-Fe alloys from Yubdo containing PGM inclusions such as andrieslombaardite in the Yubdo-Alaskan-type complex were formed at some post-magmatic stage owing to PGE remobilisation during hydrothermal or metamorphic episodes.

From individual elements to macroscopic materials: in search of new superconductors via machine learning

An approach to supervised classification and regression of superconductive materials is proposed which builds on the DeepSet technology. This enables us to provide the chemical constituents of the examined compounds as an input to the algorithm, while avoiding artefacts that could originate from the chosen ordering in the list. The performance of the method are successfully challenged for both classification (tag a given material as superconducting) and regression (quantifying the associated critical temperature). We then searched through the International Mineralogical Association list with the trained neural network. Among the obtained superconducting candidates, three materials were selected to undergo a thorough experimental characterization. Superconductivity has been indeed confirmed for the synthetic analogue of michenerite, PdBiTe, and observed for the first time in monchetundraite, Pd2NiTe2, at critical temperatures in good agreement with the theory predictions. This latter is the first certified superconducting material to be identified by artificial intelligence methodologies.

Calcioancylite-(La), (La,Ca)2(CO3)2(OH,H2O)2, a new member of the ancylite group from Gejiu nepheline syenite, Yunnan Province, China

AbstractCalcioancylite-(La), ideally (La,Ca)2(CO3)2(OH,H2O)2, has been discovered from nepheline syenite of the Gejiu alkaline complex in the Honghe Hani and Yi Autonomous Prefecture, Yunnan Province, China. The mineral occurs as aggregates of subhedral grains, and the size of single crystals varies between 5–20 μm. Calcioancylite-(La) is colourless to pale pinkish grey and has transparent to translucent lustre. It is brittle with a Mohs hardness of 4. The calculated density is 4.324 g/cm3. The mineral is biaxial (−), with α =1.662, β = 1.730, γ = 1.771, 2Vmeas. = 70°(1) and 2Vcalc. = 73°. Electron microprobe analysis for holotype material yielded an empirical formula of (La0.58Ce0.55Pr0.14Nd0.10Ca0.39Sr0.20K0.04)Σ2.00(CO3)2[(OH)1.25F0.06⋅0.69H2O]Σ2.00. Calcioancylite-(La) is orthorhombic, with space group Pmcn, a = 5.0253(3) Å, b = 8.5152(6) Å, c = 7.2717(6) Å, V = 311.17(4) Å3 and Z = 2. By using single-crystal X-ray diffraction, the crystal structure has been determined and refined to a final R1 = 0.0652 on the basis of 347 independent reflections (I > 2σ). The seven strongest powder X-ray diffraction lines [d in Å (I) (hkl)] are: 2.334 (100) (013), 2.970 (80) (121), 4.334 (75) (110), 3.678 (68) (111), 2.517 (55) (200), 2.647 (47) (031) and 2.077 (44) (221). Calcioancylite-(La) is the La-analogue of calcioancylite-(Ce) and is a new member of ancylite-group minerals. The mineral and its name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2021-090).