Galena–tetrahedrite intergrowth textures have been observed in some quenched run products of melting experiments conducted at 500 and 600°C in the systems ZnS–PbS–FeS–Cu2S–Sb2S3 and ZnS–PbS–FeS–Cu2S–Sb2S3–As2S3, using the evacuated silica-tube method. At 600°C the intergrowth formed an interface between sulfide melt and galena, whereas at 500°C it existed as inclusions partially embedded or completely embedded within tetrahedrite. At 600°C tetrahedrite was absent in PbS-bearing experiments, instead galena and melt were a part of the equilibrium phase assemblage. From the disposition of the galena–tetrahedrite intergrowths at 500°C it is evident that droplets of galena–tetrahedrite melt coexisted with tetrahedrite or tetrahedrite + galena and gave rise to these intergrowths upon quenching. The intergrowths coexisting with galena probably represent compositions on the galena-rich liquidus in the galena–tetrahedrite binary and those coexisting with tetrahedrite represent points on the tetrahedrite-rich liquidus. A eutectic at galena:tetrahedrite = ~30:70, very close to 500°C is apparent. It is clearly indicated that galena–tetrahedrite intergrowths can be formed by sulfide partial melting, and could be used as a potential indicator of partial melting in metamorphosed sulfide ore deposits.

Tourmaline from the Solnechnoe hydrothermal granitoid-related tin deposit in the Khabarovsk Krai, Russian Far East has been studied with electron microprobe, infrared and Mössbauer spectroscopy. Tourmaline formed in three distinct stages with different types of chemical substitution. Tourmaline from the first unmineralised stage is classified as dravite or schorl, which could be enriched locally in Ca, the X-site vacancy and F. This tourmaline is characterised by the Fe ↔ Mg and X vacancy + Al ↔ Na + Fe substitutions. The second, molybdenum-stage tourmaline, is schorl–dravite and fluor-schorl–fluor-dravite enriched in Ca, and a few compositions belong to the calcic group. The predominant substitution is Ca + Mg ↔ Na + Al. The third, tin-stage tourmaline, is classified as schorl–dravite with some tourmalines being fluor-schorl, oxy-schorl, foitite and magnesio-foitite. The tin-stage tourmaline is characterised by the substitutions Fe2+ ↔ Mg, Altot + O2– ↔ Fe2+ + OH–, and Fe3+ ↔ Altot. An increase of the Fe3+/Fetot value from 3–9% in the molybdenum stage to 12–16% in the tin-stage tourmalines indicates an increase in oxidation potential, which possibly contributed to cassiterite deposition. Comparison of tourmalines from greisen, porphyry and intrusion-related tin deposits worldwide shows they differ in primary chemical substitutions so can be characterised by this mechanism. The Fe3+/Fetot value in tourmaline also appears to be one of the indications for the tin deposit type. The Fe3+/Fetot value increases from <10% in greisen tourmaline through 15% in tourmaline from intrusion-related deposits to 20% in tourmaline from porphyry deposits.

Synthesis and solubility studies of onoratoite have been undertaken to determine the role of this rare secondary phase in the immobilization of Sb and the conditions responsible for its formation in the supergene zone. Solubility studies were undertaken at 298.15 K. A value of ΔGfθ (Sb8O11Cl2, s, 298.15 K) = –2576 ±12 kJ mol–1 was derived. Calculations involving sénarmontite, Sb2O3, klebelsbergite, Sb4O4SO4(OH)2 and schafarzikite, FeSb2O4, show that onoratoite is a thermodynamically stable phase only at negligible activities of SO42–(aq) and low activities of Fe2+(aq), at low pH and very high activities of Cl–(aq). This explains why onoratoite is such a rare secondary phase and why it cannot exert any significant influence on the dispersion of Sb in the supergene environment.

The hydroxy-sulphide yushkinite from the type deposit has been re-examined by electron probe microanalysis and reflectance measurement. The EPMA indicates minor Cu (up to 1.5 wt.%) and confirms an excess of V. Taking into account its composite structure (brucite-like hydroxide layer alternating with a berndtite-type sulphide layer) the proposed structural formula is, with the addition of minor intercalated Cu: [(Mg0.71Al0.36V0.03)Σ1.10(OH)2.18O0.02]Cu0.02 [VS2]. At the crystal scale, some crystal edges give a variable excess of Si and Al (in the 1/1 ratio), indicating a late topotactic intergrowth with a layered alumino-silicate (or a composite silicate-sulphide). New specular reflectance data are given in air and oil from 400 to 800 nm, with the polarization plane parallel or perpendicular to the elongation. The refractive index n and absorption coefficient k are given; no absorption band exists in the perpendicular position, with constant n close to 1.9, and k to 0.3. In a parallel position, a pseudo-transparency window is centred around 500–520 nm (∼2.4 eV). The main absorption band, centred around 730 nm (∼1.7 eV), corresponds probably to a transition t2g → eg related to intra-layer V-V bonding. Charge transfer from the brucite-type layer to the VS2 one, strictly controlled through H-bonding, induces a mean formal valency of V close to 3.6. Yushkinite is compared with other synthetic layered hydroxy-sulphides, as well as brucite-type intercalated compounds.

Gismondine is a monoclinic mineral but prior to X-ray determination of its unit cell it was variously regarded as orthorhombic, monoclinic, or triclinic on account of its intricate twinning. A study of gismondine crystals from Osa Quarry, near Rome, indicates that the morphologically dominant form is {32} which by twinning about the normal to {100} produces penetration-twinned octahedral crystals united on (100) and (001). Gismondine has poor cleavage on {32} optic plane is (010) and γ:[001] = 42.5° (in obtuse β).

Four specimens of the roméite-group minerals oxyplumboroméite and fluorcalcioroméite from the Långban Mn-Fe deposit in Central Sweden were structurally and chemically characterized by single-crystal X-ray diffraction, electron microprobe analysis and infrared spectroscopy. The data obtained and those on additional roméite samples from literature show that the main structural variations within the roméite group are related to variations in the content of Pb2+, which is incorporated into the roméite structure via the substitution Pb2+→A2+ where A2+ = Ca, Mn and Sr. Additionally, the cation occupancy at the six-fold coordinated B site, which is associated with the heterovalent substitution BFe3+ + Y☐→BSb5++YO2-, can strongly affect structural parameters.

Chemical formulae of the roméite minerals group are discussed. According to crystal-chemical information, the species associated with the name ‘kenoplumboroméite’, hydroxycalcioroméite and fluorcalcioroméite most closely approximate end-member compositions Pb2(SbFe3+)O6☐, Ca2(Sb5+Ti) O6(OH) and (CaNa)Sb2O6F, respectively. However, in accord with pyrochlore nomenclature rules, their names correspond to multiple end-members and are best described by the general formulae: (Pb,#)2(Sb,#)2O6☐, (Ca,#)2(Sb,#)2O6(OH) and (Ca,#)Sb2(O,#)6F, where ‘#’ indicates an unspecified charge-balancing chemical substituent, including vacancies.

Single crystals of Mg2GeO4 spinel, a stable analogue to mantle ringwoodite at atmospheric pressure up to 800°C, were synthesized from Mg2GeO4 olivine in hydrous conditions at 1.9 GPa and ∼1000°C. Infrared (IR) spectra show OH-stretching peaks at 3531 and 3502 cm–1. Quantification of IR spectra reveals hydrogen in the order of 5 to 10 ppm wt. H2O. A complete hydrogen/deuterium exchange was achieved at 700°C leading to a diffusion coefficient of deuterium of ∼3x10–14 m2/s. This value is of the same order as diffusion coefficients observed in other mantle minerals, such as garnet and diopside.

The O–O distance of ∽ 2.9 Å calculated from the spectra of Mg2GeO4 spinel is consistent with the GeO4 tetrahedra edge length known from crystal-structure data. Whereas the hydration mechanism and the site occupancies involved are still in discussion for mantle spinel, the IR measurements on Mg2GeO4 confirm the idea of protonation at the tetrahedral edges.

Two tourmaline crystals with a blue growth zone at the analogous pole, respectively from the San Silvestro and the Fucili pegmatites, located in the San Piero in Campo village, Elba Island (Tyrrhenian Sea, Italy), have been described for the first time using compositional and spectroscopic data to define their crystal-chemical aspects and the causes of the colour. Compositional data obtained by electron microprobe analysis indicate that both tourmalines belong to the elbaite–fluor-elbaite series. The upper part of each crystal is characterised by an increased amount of Fe (FeO up to ~1 wt.%) and a Ti content below the detection limit. Optical absorption spectra recorded on the blue zone of both samples show absorption bands caused by spin-allowed d-d transitions in [6]-coordinated Fe2+, and no intervalence charge transfer Fe2+-Ti interactions, indicating that Fe2+ is the only chromophore. Mössbauer analysis of the blue zone of the Fucili sample confirmed the Fe2+ oxidation state, implying that the redox conditions in the crystallisation environment were relatively reducing. The presence of colour changes at the analogous termination during tourmaline crystal growth suggests a change in the composition of the crystallisation environment, probably associated with a partial opening of the system.

A metallographic study has been made of the macroscopic and microscopic features of the Brenham pallasite. The microprobe has been used to investigate the condition of kamacite inter-faces with second kamacite grains, olivine, schreibersite, troilite, and taenite and of taenite interfaces with olivine. The results indicate that grain-boundary migration of nickel may be important in these structures.

The new mineral scenicite (IMA2021-057), [(UO2)(H2O)2(SO4)]2⋅3H2O, was found in the Green Lizard, Giveaway–Simplot, Markey and Scenic mines, White Canyon district, San Juan County, Utah, USA, where it occurs as a secondary phase on granular quartz matrix in association with various combinations of deliensite, gypsum, natrozippeite, rietveldite and shumwayite. Scenicite crystals are transparent, light green yellow, poorly formed blades or prisms, up to 0.1 mm in length. The mineral has white streak and vitreous lustre. It exhibits bright greenish-white fluorescence (405 nm laser). It is brittle with irregular, curved fracture and a Mohs hardness of ~2. It has excellent {100} and good {001} cleavages. The calculated density is 3.497 g cm–3. Optically, the mineral is biaxial (–) with α = 1.556(2), β = 1.573(2), γ = 1.576(2) (white light); 2V = 45(3)°; extreme r < v dispersion; orientation: X = c, Y = a, Z = b; pleochroism: X and Y = colourless, Z = light green–yellow; and X = Y < Z. The Raman spectrum exhibits bands consistent with UO22+, SO42– and O–H. Electron microprobe analysis provided the empirical formula U1.996S2.005O19H13.997. The five strongest powder X-ray diffraction lines are [dobs Å(I)(hkl)]: 7.69(70)(201), 5.63(100)(111), 4.92(84)(202,310), 4.80(93)(401) and 3.398(55)(020,120,511,601). Scenicite is orthorhombic, Pca21, a = 21.2144(15), b = 6.8188(3) c = 11.2554(6) Å, V = 1628.18(16) Å3 and Z = 4. In the structure of scenicite (R1 = 0.0365 for 1259 I > 2σI), linkages of pentagonal bipyramids and tetrahedra form an infinite neutral [(UO2)(SO4)(H2O)2] chain. The structure of shumwayite contains topologically identical chains.

Electron microprobe analyses are presented for astrophyllite-group minerals from hydrothermal veins and pegmatites of the Ilimaussaq complex, South Greenland. The analyses fall mainly into two groups: (1) niobophyllites with the highest Nb/(Nb+Ti) ratios yet recorded (∼0.9), occurring only in the veins, and (2) an essentially continuous sequence from astrophyllite to niobophyllite with Nb/(Nb+Ti) up to 0.6, found in veins and pegmatites. It is highly likely that there is complete solid solution between astrophyllite and niobophyllite. More limited substitution of Mn for Fe has resulted in the formation of kupletskite in some rocks. Altered zones in certain astrophyllites and niobophyllites have compositional features similar to the type ‘hydroastrophyllite’. The astrophyllite-group minerals in the hydrothermal veins crystallized at temperatures below 400°C at 1 kbar and under high pH and low oxygen fugacity, whereas those in the pegmatites were formed from water-rich melts which were hotter (≥450°C), less basic and more oxidized.

Zolotarevite (IMA2020-076), ideally Na5Zr[Si6O15(ОН)3]⋅2–3H2O, is а new mineral of the lovozerite group. The mineral was found in a leucocratic nepheline syenite from Kedykverpakhk Mt., Lovozero alkaline massif, Kola Peninsula, Russia. It occurs as anhedral grains up to 1 mm across and is associated with microcline–perthite, nepheline, sodalite, aegirine, lamprophyllite, lueshite, umbozerite, lomonosovite, nastrophite, a mineral of the kazakovite–tisinalite series, sphalerite and löllingite. Zolotarevite is cherry red, with a vitreous lustre and white streak. The mineral is brittle, with a Mohs hardness of 5. Cleavage was not observed; the fracture is uneven. The measured density is 2.75(5) g⋅cm–3, the density calculated using the empirical formula and single-crystal unit-cell parameters is 2.85 g⋅cm–3. Zolotarevite is anomalously biaxial (–), α = 1.580(2), β = 1.600(2) and γ = 1.602(2) (for λ = 589 nm); 2Vmeas < 10°. Chemical data (electron microprobe, wt.%) are: Na2O 20.41, СаО 0.42, MnO 3.49, Fе2O3 0.55, SiO2 52.46, ТiO2 1.34, ZrO2 11.33, H2O (calculated from the structural formula) 10.20, total 100.20. The empirical formula based оn 6 Si atoms per formula unit is Na4.53Zr0.63Mn0.34Ti0.11Ca0.05Fe3+0.05Si6O14.43(ОН)3.56(H2О)2.11. Zolotarevite is trigonal, space group R${\bar 3}$m, with a = 10.294(6) Å, c = 13.115(8) Å, V = 1203.7(16) Å3 and Z = 3. The crystal structure was solved from single-crystal data and refined to R1 = 0.049. The strongest lines of the powder X-ray diffraction pattern [d in Å (I) (hkl)] are: 7.37 (69) (101); 5.26 (56) (012); 3.686 (64) (202); 3.330 (79) (113); 3.265 (99) (211), 2.640 (100) (024) and 2.576 (60) (220). Zolotarevite is unique in that it is a highly hydrated lovozerite-group mineral with the B site occupied by variable amounts of H2O.

Sideronatrite [Na2Fe(SO4)2(OH)·3H2O] occurs as yellow botryoidal encrustations on low cliffs of weathered pyrite-bearing mudstones at Barton-on-Sea, Hampshire, England. Extensive areas of the cliffs, up to ∼100 m2, are coated with sideronatrite and its low solubility in cold water secures its longevity. Dry samples of sideronatrite convert readily to metasideronatrite [Na2Fe(SO4)2(OH)·H2O], the reaction to sideronatrite being reversible. Sideronatrite, it is suggested, forms as a result of weathering of pyrite that is present in the argillaceous sediments and reaction with Na from the sea-salt spray.

The new mineral wrightite, K2Al2O(AsO4)2, was found in 1983 at a fumarole on the Second scoria cone, Northern Breakthrough, Great Fissure eruption, Tolbachik volcano, Kamchatka peninsula, Russia, where it occurs as light yellow aggregates of transparent tabular crystals, with an average size of 0.05 mm × 0.03 mm × 0.005 mm. Wrightite is orthorhombic, space group Pnma, with the unit-cell parameters a = 8.230(5), b = 5.555(4), c = 17.584(1) Å, V = 803.9(6) Å3 and Z = 4 (from powder data). The empirical formula is (K1.69Na0.38)Σ2.07(Al1.80Fe0.24)Σ2.04As1.96O9. The crystal structure (R1 = 0.043) consists of Al2O(AsO4)2 layers in the ab plane with clusters of edge-sharing AlO6 octahedra. Each layer contains two independent isolated AsO4 tetrahedra and two AlO6 octahedra. AlO6 octahedra are linked by edges, forming zigzag chains along the b axis inside the Al–As layer. Eight- and six-coordinated K atoms are located in the interlayer space between Al2O(AsO4)2 layers. The mineral is biaxial (−), α =1.679(2), β =1.685(2), γ (calc.) =1.687; 2V(meas.) = 62(10)° (λ = 589 nm). The strongest lines in the powder X-ray diffraction pattern [d,Å(I)(hkl)] are: 8.77(36)(002); 4.458(17)(111); 4.010(19)(201,013); 3.875(19)(104) and 2.972(100)(015). The mineral was named in honour of Adrian Carl Wright, Emeritus Professor at the University of Reading, UK.

We show how different aspects of a model of the complex disordered structure of wüstite, Fe1−xO, affect the pair distribution function (PDF) and powder diffraction pattern. The aim is to assess the efficacy of using these techniques to determine details of local structure. The different aspects include the nature of the individual defect clusters, the nature of the paracrystalline superlattice on which they are distributed and the ‘size-effect’ relaxation of the basic rocksalt FeO matrix around the defects. The results show that PDF data are sensitive to those aspects of the models that have a significant effect on the populations of interatomic spacings but are less able to determine correlation structures in the samples if these do not have a substantial interaction with interatomic separations.

Heyerdahlite, ideally Na3Mn7Ti2(Si4O12)2O2(OH)4F(H2O)2, is a new astrophyllite-supergroup mineral from the Larvik Plutonic complex, Norway. Heyerdahlite was found in a nepheline-syenite pegmatite with albite, aegirine, hastingsite/magnesio-hastingsite, kupletskite, lorenzenite and pyrophanite. Heyerdahlite is colourless to pale brown, transparent and has a vitreous lustre. Mohs hardness is 3, Dcalc. = 3.245 g/cm3. Heyerdahlite is biaxial (+), α = 1.694(2), β = 1.710(5), γ = 1.730(5), 2Vmeas. = 80(4)° and 2Vcalc. = 84.5°. Cleavage is perfect parallel to {001}. The empirical formula based on 32.18 (O + F) apfu is (Na1.18K0.68Rb0.12Cs0.01Pb0.01)Σ2Na1.00(Mn6.29Zn0.23Mg0.07Zr0.04${\rm Fe}_{{\rm 0}{\rm. 03}}^{{\rm 2 +}} $Ca0.01Na0.34)Σ7.01(Ti1.78Nb0.17 Mg0.03Zr0.02)Σ2(Si8.03O24)O2[(OH)3.92F0.08]Σ4F1.00[(H2O)1.18□0.82]Σ2, for Z = 1. Heyerdahlite is triclinic, space group P$\bar 1$, a = 5.392(2), b = 11.968(4), c = 11.868(4) Å, α = 112.743(8), β = 94.816(7), γ = 103.037(8)° and V = 675.6(7) Å3. The crystal structure was refined to R1 = 4.44% for 3577 unique (Fo > 4σF) reflections. In the crystal structure of heyerdahlite, there are four [4]T sites occupied by Si. The [6]D site is occupied mainly by Ti. The T4O12 astrophyllite ribbons composed of SiO4 tetrahedra and D octahedra constitute the H (Heteropolyhedral) sheet. In the O (Octahedral) sheet, there are four Mn-dominant [6]M(1–4) sites. Two H sheets and one central O sheet form the HOH block, and adjacent HOH blocks link via a common ${\rm X}_{\rm D}^{\rm P} $ anion of the two D octahedra. In the I (Intermediate) block between HOH blocks, there are two interstitial cation sites, A and B, and a WA site, partly occupied by H2O. The A site splits into two sites, [12]A(1) and [6]A(2), partly occupied by K and Na, respectively, with A(1)–A(2) = 0.754 Å. The aggregate content of the A site is ideally Na2 apfu. The [10]B site is occupied by Na. The WA site is ideally occupied by (H2O)2 pfu. The mineral is named after the Norwegian explorer Thor Heyerdahl (1914–2002), who was born in Larvik.

The new eudialyte-group mineral amableite-(Ce), ideally Na15[(Ce1.5Na1.5)Mn3]Mn2Zr3□Si[Si24O69(OH)3](OH)2⋅H2O, was discovered in a peralkaline pegmatite at Saint-Amable Sill, Montérégie, Québec, Canada. The associated minerals are albite, microcline, aegirine, serandite, natrolite, yofortierite, and an unidentified titanosilicate forming minute grains. Amableite-(Ce) occurs as yellow equant or thick tabular crystals up to 2 mm across. The observed crystal forms are {0001}; the subordinate forms are {11$\bar{2}$0}, {10$\bar{1}$1}, and {10$\bar{1}$0}. Amableite-(Ce) is brittle, with a Mohs hardness of 5. D(meas) = 2.89(1), D(calc) = 2.899 g⋅cm–3. Amableite-(Ce) is optically anomalously biaxial (+) with α ≈ β = 1.603(2) and γ = 1.608(2). The chemical composition is (wt.%, electron microprobe, H2O measured by means of a modified Penfield method): Na2O 14.20, K2O 0.41, CaO 1.89, MnO 8.25, Fe2O3 2.40, La2O3 3.10, Ce2O3 4.19, Pr2O3 0.16, Nd2O3 0.59, SiO2 49.41, ZrO2 11.17, HfO2 0.24, TiO2 0.68, Nb2О5 1.54, Cl 0.26, H2O 1.70, –O≡Cl –0.06, total 100.13. The crystal structure was determined using single-crystal X-ray diffraction data and refined to R1 = 0.0423. Amableite-(Ce) is trigonal, space group R3, with a = 14.1340(3) Å, c = 30.3780(11) Å and V = 5255.6(3) Å3. The crystal-chemical formula is (Na12.93K0.27Ce0.06)Σ13.26[(Mn2.49Ce0.30Ca0.21)Σ3.00(Ce1.14Na1.04Ca0.82)Σ3.00](Mn1.05Fe0.90□1.05)Σ3.00(Zr2.85Ti0.12Hf0.03)Σ3.00(□0.40Nb0.36Si0.24)Σ1.00(Si0.88□0.12)Σ1.00[Si24(O70.44(OH)1.56)Σ72.00][(OH)2.20(H2O)1.27]Σ3.47Cl0.22 (Z = 3). Infrared and Raman spectra are given. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %)(hkl)] are: 11.34 (51)(101), 7.06 (76)(110), 4.312 (63)(205), 3.783 (38)(033), 3.538 (43)(027, 220), 2.963 (84)($\bar{3}$45), 2.837 (100)(404). The mineral is named after the discovery locality.

The incorporation of pertechnetate (TcO4–) into feldspathoids produced by alkaline alteration of aluminosilicate clays may offer a potential treatment route for 99Tc-containing groundwater and liquors. Kaolinite was aged in NaOH to determine the effect of base concentration, temperature, and solution composition on mineral transformation and pertechnetate uptake. In all reactions, increased temperature and NaOH concentration increased the rate of kaolinite transformation to feldspathoid phases. In reactions containing only NaOH, sodalite was the dominant alteration product; however, small amounts (6–15%) of cancrinite also formed. In experiments containing NaOH/Cl and NaOH/NO3 mixtures, sodalite and nitrate cancrinite were crystallized (at 70°C), with no reaction intermediates. The addition of SO42– crystallized sulfatic sodalite at 40 and 50°C, but at higher temperatures (60 and 70°C) sulfatic sodalite transforms to vishnevite (sulfatic cancrinite). In experiments where a pertechnetate tracer was added (at ∼1.5 μmol l–1), only 3–5% of the 99Tc was incorporated into the feldspathoid phases. This suggests that the larger pertechnetate anion was unable to compete as favourably for the internal vacancies with the smaller OH–, NO3–, SO42– or Cl– anions in solution, making this method likely to be unsuitable for groundwater treatment.

The old mine Settlingstones, situated three miles north of Haydon Bridge in the county of Northumberland, was originally worked as a lead mine, but, during the htst fifty years, as the vein has been explored farther west, it has attained far greater importance as the largest and most consistent producer of witherite in the British Isles. The Settlingstones main vein has a direction approximately north-east and southwest, and has been proved for a distance of nearly 1½ miles. The vein has varied in width from 3 feet up to 40 feet, the most productive witherite-bearing portion averaging 10 to 12 feet. The enclosing rocks are sandstones ('whetstones') and shales ('plate') of Carboniferous age, and dolerite (Whin-sil) which here attains a thickness of a little over 21 fathoms.

Pargas in Finland and MansjSand and Tennberg in Sweden are the only three Fennoscandian contact metamorphic limestone occurrences of which systematic accounts have been published; in the first case by A. Laitakari (1) and in the two latter ones by the present author (2, 3). A more complete analytical programme would have been desirable, and unfortunately many of the analyses are incomplete, especially as regards the determination of the valency of the iron. Nevertheless, the available data, and a few I have been able to add later, may suffice to give us a general idea of the paragenetical and chemical differences between these Archaean mineral parageneses and those of much younger age which occur in connexion with the limestone masses associated with the alkaline occurrence of Alnö in Sweden.