A neutron activation analysis of one of the crystals of ‘monalbite’, which was monoclinic at room temperature, shows that it contains a large proportion of potassium. It is thus not a polymorph of pure NaAlSi3O8. The contamination occurred by transfer of K through the atmosphere of the furnace from potassium-bearing ceramic materials.

Experimental breakdown of staurolite + inclusions of albite and muscovite (representing an aluminous Fe-rich metapelitic composition) occurs within the KNFMASH system at 800°C and 0.1 GPa under fluid-present conditions over periods of 2 days to 8 weeks. The overall melt-producing reaction is staurolite + muscovite + plagioclase + vapour = hercynite + corundum + mullite + quartz + liquid, and involves three reactions; staurolite + vapour = hercynite + corundum + quartz + liquid, albite + vapour = mullite + liquid, and muscovite + vapour = mullite + liquid. Melt (glass) compositions are siliceous (77.2–64.5 wt.% SiO2), peraluminous (A/CNK = 1.5–5.5), and have granite-trondjhemite compositions in terms of normative Ab-Ab-Or contents. Textures indicate that quartz formed later than corundum. The corundum + quartz + hercynite assemblage after staurolite is considered to be metastable and only likely to be found in nature where staurolite-bearing rocks have undergone rapid heating and melting followed by quenching.

Although the Mendip Hills, as a district, have from time to time received the attention of geologists, details of the mineral occurrences are, on the whole, remarkably scarce. Mining was formerly carried on on the Hills for many centuries, but mineralogy as a science had not been sufficiently developed at the time when the mines were most active, and little interest was taken in the minerals other than those suitable or required for commercial and industrial purposes. Even in later years, when, in the course of treating old refuse and tailings left by earlier miners and of various attempts to resuscitate the mining industry, much material must have been available for examination, little attention seems to have been paid to it, or to the numerous quarries that were opened in the Carboniferous Limestone.

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.

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.

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.

An investigation of the relative stabilities and equations of state of possible Fe3S polymorphs was conducted using first-principles pseudopotential calculations. These calculations were based on density functional theory and performed using ultrasoft Vanderbilt pseudopotentials within the generalized gradient approximation. In accord with experiment, we found that the tetragonal Fe3P-type polymorph is the only stable phase along the 0 K isotherm as a function of pressure. Fe3S exhibits permanent magnetism at ambient conditions (Fei et al., 2000), but magnetism is suppressed by pressure and temperature, and therefore non-magnetic data are appropriate ones to use for modelling planetary interiors. For this reason, and because the Fe3P-type polymorph of Fe3S contains 32 atoms per unit cell it was impractical to incorporate magnetic properties into the simulations of this phase, we studied the behaviour of the non-magnetic phase. We obtained values of 250 GPa for the bulk modulus, K0, and 4.61 for its first derivative withrespect to pressure, K0′, by fitting a 3rd order Birch-Murnaghan equation of state to the calculated internal energy as a function of volume for the non-magnetic Fe3P-type Fe3S. This suggests that a pressure far greater than that expected in the Martian interior would be needed to achieve a density comparable to that of the Martian core. We therefore conclude that it is unlikely that the core of Mars contains significant amounts of solid Fe3S.

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.

Bassoite, ideally SrV3O7·4H2O, is a new mineral from the Molinello manganese mine, Val Graveglia. eastern Liguria, northern Apennines, Italy. It occurs as black euhedral to subhedral grains up to 400 urn across, closely associated with rhodonite, quartz and braunite. Bassoite is opaque with a sub-metallic lustre and a black streak. It is brittle and neither fracture nor cleavage was observed; the Vickers micro-hardness (VHN100) is 150 kg/mm (range 142—165; corresponding to a Mohs hardness of 4—41/2). The calculated density is 2.940 g/cm3 (on the basis of the empirical formula and X-ray single-crystal data). Bassoite is weakly bireflectant and very weakly pleochroic from grey to a dark green. Internal reflections are absent. The mineral is anisotropic, without characteristic rotation tints. Reflectance percentages (Rmin and Rmax) for the four standard COM wavelengths are 18.5%, 19.0% (471.1 nm); 17.2%, 17.8% (548.3 nm); 16.8%, 17.5% (586.6 nm) and 16.2%, 16.8% (652.3 nm), respectively.

Bassoite is monoclinic, space group P21/m, with unit-cell parameters: a = 5.313(3) Å, b = 10.495(3) Å, c = 8.568(4) Å, β = 91.14(5)°, V= 477.7(4) Å3, a:b:c = 0.506:1:0.816, and Z = 2. The crystal structure was refined to R1 = 0.0209 for 1148 reflections with Fo > 4σ(Fo) and it consists of layers of VO5 pyramids (with vanadium in the tetravalent state) pointing up and down alternately with Sr between the layers (in nine-fold coordination). The nine most intense X-ray powder-diffraction lines [d in Å (I/I0) (hkt)] are: 8.5663 (100) (001); 6.6363 (14) (011); 3.4399 (14) (1̄21); 3.4049 (17) (121); 2.8339 (15) (1̄22); 2.7949 (11) (122); 2.6550 (15) (200); 2.6237 (11) (040) and 1.8666 (15) (240). Electron microprobe analyses produce a chemical formula (Sr0.97Ca0.02Na0.01)V3.00O74H20, on the basis of 2(Sr+Ca+Na) = 1, taking the results of the structure refinement into account. The presence of water molecules was confirmed by micro-Raman spectroscopy. The name honours Riccardo Basso (b. 1947), full professor of Mineralogy and Crystallography at the University of Genova. The new mineral and mineral name have been approved by the Commission on New Minerals, Nomenclature and Classification, IMA (2011-028).

Oscarkempffite, ideally Ag10Pb4(Sb17Bi9)∑=26S48, is a new mineral species found in old material (1929–30) from the Colorada vein, Animas mine, Chocaya Province, Department of Potosi, Bolivia. It is associated with aramayoite, stannite, miargyrite, pyrargyrite and tetrahedrite. Oscarkempffite forms anhedral grains and grain aggregates up to 10 mm across. The mineral is opaque, greyish black with a metallic lustre; it is brittle without any discernible cleavage. In reflected light oscarkempffite is greyish white, pleochroism is distinct, white to dark grey. Internal reflections are absent. In crossed polars, anisotropism is distinct with rotation tints in shades of grey. The reflectance data (%, air) are: 39.9, 42.6 at 470 nm, 38.6, 41.7 at 546 nm, 38.1, 41.2 at 589 nm and 37.3, 40.6 at 650 nm. Mohs hardness is 3–3½, microhardness VHN50 exhibits a range 189–208, with a mean value 200 kg mm–2. The average results of four electron-microprobe analyses in a grain are: Cu 0.24(7), Ag 14.50(8), Pb 11.16(14), Sb 28.72(16), Bi 24.56(17), S 20.87(5), total 100.05(6) wt.%, corresponding to Cu0.24Ag9.92Pb4.00Sb17.36Bi8.64S47.84 (on the basis of Me + S = 88 apfu). The simplified formula, Ag10Pb4Sb17Bi9S48, is in accordance with the results of a crystal-structure determination. The density, 5.8 g cm–3, was calculated using the ideal formula. Oscarkempffite has an orthorhombic cell with a = 13.199(2), b = 19.332(3), c = 8.249(1) Å, V = 2116.3(5) Å3, space group Pnca and Z = 1. The strongest eight lines in the (calculated) powder-diffraction pattern are [d in Å(I)hkl]: 3.66(35)(122), 3.37(70)(132), 3.34(100)(250), 2.982(55)(312), 2.881(86)(322), 2.733(29)(332), 2.073(27)(004) and 2.062(31)(182). Comparison with gustavite, andorite and roshchinite confirms its independence as a mineral species.

The petrography and geochemistry of a suite of dolerite dykes emplaced into orthogneisses of the Jotun Nappe, central southern Norway, are described. The dolerites, which appear to be tholeiitic in character, show well-developed ophitic and doleritic textures and are not foliated. They contain corona structures of six types which represent the various stages of reaction between olivine or clinopyroxene and plagioclase, and oxide grains and plagioclase. Corona growth always proceeds after the plagioclase has become clouded with numerous extremely fine opaque particles, and reaches its fullest development in rocks with the most heavily clouded plagioclase. Garnet grows in coronas only in rocks with Fe2O3/(Fe2O3 + FeO) = 0.20 to 0.27. The ratio MgO/MgO + Fe2O3 + FeO) is of lesser importance in controlling the growth of this mineral. The role of water in coronaforming reactions, and the preservation of original igneous textures indicates that the coronas are a product of post-solidification deuterism, possibly active at high pressures and temperatures, rather than of prograde metamorphism.

Found by N. Theis at a uranium prospect near Durango, Colorado. Occurs with uraninite, galena, malachite, azurite, etc. Colour pale blue-green, H = 1½, G = 4.25. Optically 2Vα ≈ 0°, α = 1.755, β = γ = 1.785; non-pleochroic. Chemical analysis on 1034 µg gave CuO 33.3 %, ZnO 33.1, CaO 0.3, As2O5 14.8, Sb2O5 7.0, H2O 10.5 leading to Cu5Zn5{(As,Sb)O4}2(OH)14. The cell indexes as orthorhombic a = 8.225Å, b = 7.123, c = 14.97. Strongest lines are 14.97 (9), 7.483 (5), 4.112 (4), 3.741 (10), 2.996 (4), 2.534 (9), 1.830 (5), 1.553 (3). The mineral and name have been approved by the Commission on New Minerals and Mineral Names, IMA.

1666 moldavites from 19 localities in Bohemia and 617 moldavites from 10 localities in Moravia were measured to yield parameters L (length), B (breadth), and T (thickness). A digital computer was programmed to calculate values T/L, (L-B)/(L-T), and according to Sneed and Folk (1958) and values q = B/L, p = T/B, and F = p/q according to Zingg (1935). Averages of large numbers of values characterize Bohemian and Moravian localities. Moldavites from most localities in Bohemia are often drop-like, flat or elongate with average values of between 0·53 and 0·66 and F between 0·68 and 0·91. Moldavites from Moravia are frequently massive to spheroidal with average in the range 0·60 to 0·75 and F between 0·87 and 1·08. Among the localities in Bohemia, four have moldavites with morphological features of Moravian moldavites. The data obtained permit an interpretation that localities of moldavites with low average sphericity contain less heated material. Less heated and thus more viscous glass could have flown along shorter trajectories (Bohemia). More heated glass was ejected to geographically more distant places (Moravia) or travelled along relatively long steeper trajectories (several localities in Bohemia).

Dwornikite, (Ni1−xFex)SO4 · H2O is a member of the kieserite group, monoclinic with space group C2/c. Specimens from Minasragra, Peru with x ∼ 0.1 have a unit cell with a = 6.839(2), b = 7.582(2), c = 7.474(2) Å, and β = 117.85(2)°. The six strongest lines of the powder pattern are: 3.342 (12, 100), 4.732 (110, 70), 3.024 (200, 70), 4.754 (11, 50), 3.293 (021, 35), 2.491 (022, 35). The mineral occurs as fine grained white aggregates associated with vanadium sulphide ores containing patronite and bravoite, mixed with other oxidation products. New unit cell data for the synthetic end-member compounds NiSO4 · H2O and FeSO4 · H2O, and new X-ray powder data for retgersite (NiSO4 · 6H2O) are provided.