Zoned spherulites in greenalite-siderite-silica rocks of the Emilia-San Valentin lead-zinc deposit, Sierra de Cartagena, SE Spain, show a core of iron-rich talc, (Mgl.8Fel.2)Si4Ol0(OH)2, an intermediate zone of opal-chalcedony, and a rim of minnesotaite, (Fe2.7Mg0.3)Si4Ol0(OH)2. Crystalllization of the spherulites, presumably from undercooled silica sols carrying dissolved Mg and Fe, began with the non-equilibrium precipitation of metastable iron-rich talc; the residual fluids enveloping the growing spherulites became more iron-rich in composition until metastable equilibrium between iron-rich talc and iron-enriched residual liquid impeded the further growth of the iron-rich talc; the spherulites were then overgrown by colloidal silica flocculates and a rim of minnesotaite precipitated from the iron-enriched residual fluid. The proposed crystallization model implies that, if talc and minnesotaite represent an isomorphic series, under equilibrium conditions there is a broad immiscibility region in the series.

The development of low- and hightemperature alteration products in a 23 m section of ocean-floor basalts is described. Analcime, calcite and dioctahedral smectite are ubiquitous. Trioctahedral smectite, smectite-chlorite mixed layers, chabazite and scolecite occur in the deeper sections with Fe3+ oxides/hydroxides progressively becoming more abundant in the upper regions. The upper layers of the sequence show marked chemical reduction. High-temperature chemical changes include Na and Mg enrichment accompanied by Ca and Fe2+ losses. Superimposed low temperature changes include gains in Fe3+ K, Li, and Rb, and losses in Na, Ca, and Fe2+ Many trace elements also show consistent behaviour.

A transmission electron microscopy (TEM) investigation was undertaken in order to elucidate the nature of the structural disorder in a tobelite specimen from the sedimentary rocks of the Armorican sandstones (western France). This structural disorder may be the origin of residual electron-density maxima in difference-Fourier maps reported previously in single-crystal XRD studies of tobelite. The TEM investigation of tobelite confirmed that it is the 2M2 polytype in subfamily-B, but the ordered sequence is interrupted by numerous stacking faults parallel to (001), for which the stacking vectors belong to both subfamilies-A and -B of mica polytypes, with a prevalence of the latter. Chemical heterogeneity depending on the Si/Al ratio and Na and Mg concentration was observed at the nanoscale among different mica lamellae in a single crystal. The observed variations are consistent with a change in mica chemistry leading to interlayer vacancies which may cause shortening of the interlayer separation, as revealed by the single-crystal structure refinements.

A silver-palladium alloy with structural formula close to AgPd has been found in laterite from the Bahia lateritic gold deposit. The alloy occurs in a void of an iron oxide nodule, associated with goethite and hematite. The angular shape and protuberances of the alloy grains suggest crystal growth in a lateritic environment, indicating that the alloy is a secondary mineral precipitated during lateritisation. The oxidation of sulphides of the parent rocks probably favoured the migration of palladium and silver as transient thiosulphate and sulphite complexes. Destruction of the thiosulphate and sulphite ligands could result in precipitation of both palladium and silver as an alloy. Eh-pH phase diagrams for Pd-H2O-C1 and Ag-H2O-C1 systems show that both palladium and silver are stable in lateritic environments under lower redox potentials. Such an environment may exist at the top of the ferruginous zone due to the abundant organic matter near the surface.

Wycheproofite is a new hydrated sodium aluminium zirconium phosphate from a pegmatite vein in granite at Wycheproof, in northwestern Victoria, Australia. The mineral occurs as compact, finely fibrous masses in small cavities in the quartz/feldspar/muscovite/schorl-bearing pegmatite. The fibrous crystals are between 5 and 10 µm wide and up to several mm long. Accompanying minerals include two other zirconium phosphates — kosnarite and a new species, selwynite, the K-analogue of gainesite — as well as wardite, eosphorite, cyrilovite, leucophosphitc, rockbridgeite, a kidwellite-like mineral and saleeite. The wycheproofite aggregates are pale pinkish to brownish orange, with a vitreous to pearly lustre. The streak is colourless, fracture rough, cleavage not observed and the Mohs hardness is between 4 and 5. Optical data are incomplete due to the fibrous nature of the mineral; the indices of refraction are in the range 1.62–1.64. The measured density is 2.83 g cm−3. Chemical analysis gave (wt.%) Na2O 6.36, K2O 0.44, CaO 0.66, FeO 0.36, MnO 0.21, Al2O3 12.03, Cs2O 0.03, ZrO2 32.43, HfO2 1.24, P2O5 35.85, SiO2 0.23, F 0.34, H2O 9.0, less 0=F 0.14, Total 99.04. The simplified formula is NaAlZr(PO4)2(OH)2·H2O. Wycheproofite is triclinic with unit cell parameters a=10.926(5) Å, b = 10.986(5) Å, c = 12.479(9) Å, α= 71.37(4)°, β = 77.39(4)°, γ= 87.54(3)° V = 1375.9 Å3. For Z= 6, the calculated density is 2.81 g cm-3. The strongest lines in the X-ray powder diffraction pattern are [dobs (Å), Iobs,hkl] 2.603 (100) 040; 4.128 (80) 121; 3.711 (65) 023; 3.465 (60) 030; 8.865 (40) 101; 3.243 (35) 132. The crystal structure has not been solved due to the finely fibrous nature of the material available. The name is for the locality, which in the local Australian Aboriginal language means ‘witchie bushes growing on a hilltop’.

Data on the third occurrence of kosnarite, KZr2(PO4)3, at Wycheproof are also given.

Coaquandite, a new antimony oxy-sulphate hydrate, occurs as spheroidal knobs of silky fibres or, rarely, as tiny transparent colourless lamellar crystals on stibnite at the Pereta mine, Tuscany, Italy; it is associated with klebelsbergite, peretaite, valentinite, sulfur, gypsum, stibiconite, and senarmontite. Coquandite is triclinic P1, with a 11.434(7), b 29.77(4), c 11.314(4) Å, α 91.07(7)°, β 119.24(3)° γ 92.82(1)° . It has a cell volume of 3352(5)Å3 with Z = 12 and a calculated density of 5.78 g cm−3. The crystals, elongated along [001] and flattened on {010}, display polysynthetic twinning with (010) as the twin plane. Optically, they are biaxial (+) with z ≈ c, 2V ≫ 60° n = 2.08(5). The strongest lines of the X-ray powder pattern are [d in Å, (I), (hkl)] 14.84(50)(020), 9.27(41)(111, 110), 6.81(67)130, 3.304(93)(090), 3.092(100)(330).

Coquandite has also been found at the Cetine mine, Tuscany, Italy, and at the Lucky Knock mine, Tonasket, Okanogan County, Washington, USA. 22 microprobe chemical analyses (elemental microanalysis for H) gave Sb2O3 88.91, SO3 8.35, CaO 0.04, Na2O 0.03, H2O 1.43, total 98.76 wt.%, corresponding to the empirical formula (Sb + S = 7) Sb5.98Ca0.01Na0.01O7.96(SO4)1.02.0·78H2O, and to the idealised formula Sb6O8(SO4).H2O. The I.R. spectrum, which confirms the presence of water in the formula, is given.

A partial structural arrangement is also given: the Sb polyhedra lie in nine layers perpendicular to [010] and form 'hexagonally' shaped groups surrounded by SO4 tetrahedra.

The crystal structure of Ba2F2(S6+O3S2–), a natural thiosulphate weathering product of old smelting slags at the Surrender Mill, Yorkshire, England, UK, has been solved to R1 = 0.88% for 399 unique [Fo > 4α F] reflections and 0.91% for all 407 reflections. The compound is monoclinic, C2/m, a 15.3172(5), b 4.5898(1), c 4.6320(2) Å, β 101.449(1)º, V 319.17(2) Å3. The structure of Ba2F2(S6+O3S2–) consists of BaF2Ba layer fragments of the fluorite-type structure of frankdicksonite (BaF2) parallel to (100) alternating with layers of thiosulphate groups. The layer sequence in one unit cell is (S6+O3S2–)-BaF2Ba-(S6+O3S2–)-BaF2Ba. The structure resembles that of grandreefite, Pb2F2SO4.

Chromitite zones associated with ultramafic units of the Lysanskiy layered complex of dunite–peridotite–gabbro composition could well represent the primary source for the placers bearing platinum-group minerals (PGM) of the entire drainage of the River Sisim and its tributaries, the rivers Ko and Seyba, eastern Sayans. Alluvial gold present in the placers of River Seyba, as elsewhere in the Sisim Placer Zone, reflects mineralisation during a recent period of tectonic activity. We focus on the PGM in the Seyba suite, and in particular on the attributes of pentlandite enriched in platinum-group-elements (PGE) and the compositionally similar and recently defined ferhodsite, which were trapped in host grains of Os–Ir–Ru alloy. Both minerals formed from small volumes of fractionated Fe–Ni–Cu melt considerably enriched in the PGE. In the Seyba suite, as in several others, the amounts of PGE in ferhodsite exceeds that in pentlandite, which results in a greater proportion of vacancies than in pentlandite.

The mineral priderite has been examined by electron microprobe analysis and electron diffraction. The composition was approximately (K0.97Ba0.33)(Fe1.17Ti6.60Mg0.23)O16, which is in line with the observed superlattice periodicity of m = 5.88, there being inter-growths of m = 5 and m = 6 superstructures. A surprisingly high degree of lateral correlation between tunnel cations was noted.

The crystal structure of Na4[Cu4O2(SO4)4] MeCl (Me: Na,Cu,☐) has been solved by direct methods and refined to R1 = 0.028 using 2466 independent reflections. The compound is tetragonal with space group P4/n, a = 18.451(1)Å, c = 4.9520(2)Å, Z = 4. The two main building units running parallel to the c-axis comprise: (1) slabs containing SO4 and OCu4 tetrahedra; and (2) chains of corner sharing Me(Cl,O)6 octahedra. The displacement ellipsoids of the atoms occupying the Me sites and of the Cl ions indicate a short-range static disorder. Copper in the slabs exhibits a (4+1) coordination. Both elements form a tunnel structure in which additional Na atoms are incorporated for charge compensation. The structure is closely related to the mineral piypite (K4Cu4O2(SO4)4 MeCl (Me: Na,Cu,☐)): . Furthermore, the structure has a pronounced pseudo-translational symmetry: apart from some of the oxygen sites, all of the nineteen crystallographically distinct positions are related by a pseudo F centring.

Examples of apparent exsolution lamellae and lenticular blebs of chalcopyrite in pyrrhotite are described in orthopyroxene-bearing granulite facies rocks from two, oxidized (log10fO2 = −14 to −11), widely separated, well characterized high grade terranes: the Bamble Sector, SE Norway (795°C, 7.5 kbar) and the Shevaroy Hills Massif, Tamil Nadu, S India (750°C, 7.5 kbar). These exsolution features only occur in isolated pyrrhotite grains and not in integral pyrrhotite-pyrite-chalcopyrite-magnetite grain clusters which essentially represent an oxidation equilibrium. Reintegration of these chalcopyrite exsolution features back into the pyrrhotite host indicate Cu contents ranging from 1 to 5 wt.% in good agreement with experimental observations which indicate that pyrrhotite can take up to 7 wt.% Cu at temperatures above 800°C at pressures of ∼1 bar. This suggests that under high grade conditions these chalcopyrite exsolution features were in solid solution with pyrrhotite. Whether Cu stabilizes pyrrhotite at higher oxygen fugacities or these chalcopyrite-pyrrhotite grains represent a metastable phase is uncertain. One possibility is that the isolated pyrrhotite grains with chalcopyrite lamellae could represent grains that were preferentially not exposed to infiltrating fluids, which oxidized the pyrrhotites in other areas of the sample. A second possibility is that either these grains had enough Cu to stabilize them during pervasive infiltration of oxidizing fluids or that they represent a metastable phase with respect to the overall oxygen fugacity of the sample. The two conclusions that can be drawn from these observations are, firstly, that it is possible for pyrrhotite and chalcopyrite to form a limited solid solution at granulite facies temperatures and pressures under relatively high oxidizing conditions, i.e. 1.5 log units above fayalite-magnetite-quartz, at 800°C and 8 kbar. Secondly, this limited solid solution should have some bearing on the stability of pyrrhotite with respect to co-existing magnetite and pyrite as a function of the oxidation state of the rock, be it inherited or fluid induced.

Carbon-14 has been identified as one of the more significant radionuclides in solid radioactive wastes in a repository, due to the potential radiological impact arising if 14C were to be released and enter the biosphere. However, the assessment of radiation doses is complicated by the major role of carbon in biological processes, and this has tended to lead to the adoption of a cautious assessment approach.

An international comparison of five models used to predict uptake of 14C to agricultural crops has been undertaken, within the BIOPROTA framework. Processes investigated include conversion of 14C-labelled CH4 into CO2 in soils, carbon accumulation in and release from soil carbon pools, gaseous emanation to, and dispersion from, the plant canopy atmosphere and, incorporation into plants by photosynthesis.

For a unit rate of entry of 14C to soil, modelled activity concentrations in cereal crops differ by three to five orders of magnitude. This reflects, in part, differing assumptions for mixing and dispersion of air above the soil surface and within the crop canopy layer. For a unit activity concentration of 14C in air, the modelled uptake to cereal crops converges significantly. Following an assumed irrigation of crops with groundwater containing unit activity of 14C, the predicted uptake to crops varied by two to four orders of magnitude, again largely dominated by assumptions regarding the canopy atmosphere. In all cases, there is some convergence in model predictions as field size increases.

A continuing programme of field research is being undertaken in parallel with the assessment work.

New guidelines for the nomenclature of polymorphs and polysomes have been approved by the the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA–CNMNC). Several cases can be distinguished. (i) Polymorphs with different crystal systems are distinguished by the prefixes cubo- (cubic), hexa- (hexagonal), tetra- (tetragonal), trigo- (trigonal), ortho- (orthorhombic), clino- (monoclinic) and anortho- (triclinic). (ii) Polymorphs with different crystal systems but showing a pseudosymmetry should show the prefix ‘pseudo-’. (iii) Polymorphs with the same crystal system but different space groups are distinguished by the prefix ‘para-’. If three or more polymorphs show the same crystal system but different space groups, the space group notation may be added as a suffix, though such a nomenclature should be avoided if possible. (iv) Polymorphs with the same space group are distinguished by the prefix ‘para-’. (v) Minerals with polymorph suffixes but with different chemical compositions cannot be considered as true polymorphs, so we recommend using the prefix ‘meta-’, which indicates a close but significantly different chemical composition. (vi) Polysomatic symbols should be placed as a suffix, which indicates the number and types of modules that alternate in the structure, such as in the högbomite supergroup, or as prefixes as in the sartorite homologous series. These recommendations have to be applied for future new mineral proposals, when the authors decide to use structural prefixes or suffixes, however modifications of historical and well-established names have to pass through the CNMNC for approval. In order to be consistent with the new guidelines, 25 mineral names are now modified: domeykite-β becomes trigodomeykite; fergusonite-(Y)-β becomes clinofergusonite-(Y); fergusonite-(Ce)-β becomes clinofergusonite-(Ce); fergusonite-(Nd)-β becomes clinofergusonite-(Nd); ice-VII becomes cubo-ice; roselite-β becomes anorthoroselite; sulphur-β becomes clinosulphur; mertieite-II becomes mertieite; mertieite-I becomes pseudomertieite; uranophane-α becomes uranophane; uranophane-β becomes parauranophane; gersdorffite-P213 becomes gersdorffite; gersdorffite-Pa3 becomes paragersdorffite; gersdorffite-Pca21 becomes orthogersdorffite; betalomonosovite becomes paralomonosovite; lammerite-β becomes paralammerite; nováčekite-I becomes hydronováčekite; nováčekite-II becomes nováčekite; halloysite-7Å becomes halloysite; halloysite-10Å becomes hydrohalloysite; metauranocircite-I becomes metauranocircite; taimyrite-I becomes taimyrite; uranocircite-II becomes uranocircite; andorite IV becomes quatrandorite; and andorite VI becomes senandorite.

The Miocene, epithermal, Ag-rich polymetallic Santo Toribio deposit is hosted by the volcanics of the Quiruvilva-Pierina subbelt, Northern Peru, which also comprises the world-class, high sulphidation Pierina deposit. The Ag-rich, alabandite-bearing veins of the Santo Toribio deposit formed during two major stages. The early stage is characterized by deposition of arsenopyrite, pyrite, quartz, Mn- sphalerite, stannite, alabandite and minor miargyrite. Sphalerite associated with this stage is exceptionally enriched in Mn (up to 14.5 wt.%) and alabandite is optically and mineralogically zoned. Its brown zones have greater Fe+Sb and smaller Mn contents than the green zones and Fe+Sb replaces Mn in its structure. During this early stage, fs2 must have been high to allow the stabilization of alabandite relative to rhodochrosite. In the second stage, the physicochemical conditions changed and the CO2/S ratio increased, causing dissolution of alabandite and the deposition of abundant rhodochrosite and a second generation of arsenopyrite, pyrite and quartz, sphalerite with chalcopyrite inclusions, mirargyrite, ramdohrite, and finally stibnite. This polymetallic ore probably formed due to an abrupt decrease in H+ and/or Cl- concentration caused by boiling or dilution of the high-salinity hydrothermal fluids and constitutes an example of “intermediate sulfidation-state” epithermal deposits.

Coarse-grained mertieite-II [Pd8(Sb,As)3] crystals (up to 2.5 mm across) with inclusions of sperrylite and intergrown with keithconnite [Pd3(Te,Bi)], cooperite-braggite, a Pt-Pd-Hg alloy, a (Pd,Pt)9Te phase and Au-Ag alloy occur in alluvial sediments in the Darya river, Aldan Shield, Russia. The primary PGM assemblage underwent alteration with formation of a very fine-grained mixture of Pd-bearing oxides and hydrated oxides. The Pd oxide/hydrated oxide aggregates (up to 100 μm wide and ~1 mm long) occur along crystallographic planes, on grain boundaries and fractures, occasionally intergrown with goethite. The Pd-O-bearing compounds formed after (1) mertieite-II (Sb content reaches 23 wt.%), (2) keithconnite (variably enriched in Te, up to 7 wt.% and Bi, up to 6 wt.%) and (3) potarite (with high Hg content, up to 35 wt.%). The variably oxidized and hydrated PGM assemblage can be attributed to supergene alteration and small-scale element redistribution under cool climatic conditions with a limited degree of leaching.

In support of the disposal system safety case for a geological disposal facility (GDF) there is a requirement to consider 'what-if' hypothetical scenarios for post-closure nuclear criticality. Although all such scenarios are considered very unlikely, one 'what-if' scenario is the mobilization of fissile material from a number of waste packages and its slow accumulation within the GDF or the immediate surroundings. Should sufficient fissile material accumulate a quasi-steady-state (QSS) transient criticality event could result. A computer model has been developed to understand the evolution and consequences of such an event.

Since a postulated QSS criticality could persist for many millennia, building confidence in the modelling approach is difficult. However, the Oklo natural reactors in Africa operated for similar durations around two billion years ago, providing a natural analogue for comparison. This paper describes the modelling approach, its application to hypothetical criticality events for a GDF, and how the model can be compared to Oklo. The model results are found to be in agreement with the observational evidence from Oklo, building confidence in the use of the QSS model to simulate postulated post-closure criticality events in GDFs.

The manganiferous amphibole juddite has been reported by a number of workers from metamorphosed manganese formations of India. The mineral is developed at the contact of pegmatite and gondite, and associated characteristically with blanfordite (manganoan aegirine-augite) and winchite (manganoan richterite-tremolite). The range of the refractive indices of the mineral and the orientation of the optic axial plane normal to (010) suggest the mineral to be of magnesioriebeckite composition. The 100 Mn2+:(Mn2++Mg+Fe2+) and 100 Fe3+:(Fe3++Alvi+Ti) ratios plotted in the glaucophane-magnesioriebeckite diagram show that eight out of nine analyses (eight new) are grouped under magnesioriebeckite composition range. It may thus be concluded that the juddites generally refer to (manganoan) magnesioriebeckite compositions. In some cases, however, the composition of juddite shows considerable departure from ideal magnesioriebeckite composition and the juddite and winchite (manganoan tremolite-richterite) show evidences of compositional transition, indicating partial miscibility. The juddites have been formed by the interaction of pegmatitic fluid on manganese ore, gondite, and other country rocks such as mica schists and diopside-forsterite marble.

A series of clinopyroxenes along the CaMgSi2O6–CaCoSi2O6 join was synthesized by quenching from melts at 1500°C and subsequent annealing at 1250°C (at 0.0001 GPa). This protocol proved to be the most effective to obtain homogenous, impurity-free and stoichiometric pyroxenes. Electron microprobe analyses in energy dispersive mode were conducted and single-crystal X-ray diffraction data were collected on Ca (CoxMg1-x)Si2O6 pyroxenes with x = 0.2, 0.4, 0.5, 0.6. Effects of cation substitution at the M1 site are described. The experimental findings of this study allow us to extend the comparative analysis of the structural features of pyroxenes with divalent cations at the M1 and M2 sites.

The crystal structure and chemical composition of two samples of fettelite from the type locality, including a portion of the holotype material, was investigated to verify if a previously proposed revision of the chemical formula was applicable, and to study the role of cation substitution for Hg that would suggest new members of the fettelite family. The crystal structure of fettelite from the type locality was found to be equivalent to that reported previously for the Chilean occurrence, and consists of an alternation of two kinds of layers along c: layer A with general composition [Ag6As2S7]2– and layer B with general composition [Ag10HgAs2S8]2+. In this structure, the Ag atoms occur in various coordination configurations, varying from quasi-linear to quasi-tetrahedral, the AsS3 groups form pyramids as are typically observed in sulfosalts, and Hg links two sulfur atoms in a linear coordination. The refined compositions for the crystals in this study, [Ag6As2S7][Ag10(Fe0.53Hg0.47)As2S8] (R100124) and [Ag6As2S7][Ag10(Hg0.79Cu0.21)As2S8] (R110042), clearly indicate that new mineral species related to fettelite are likely to be found in nature.