Alternating eclogitic amphibolites, mica schists and orthogneisses in the Schobergruppe to the south of the Tauern Window suffered a post-Upper-Ordovician progressive deformation D1-D2 which produced parallel planar-linear structures in all the rocks. Zoned garnets, preferentially oriented zoned clinopyroxenes (Jd 35-42%) and albite (An 7-9%) give evidence of high-pressure metamorphism (550-650°C 14-16 kbar) of the metabasites. Ca-amphiboles crystallized during subsequent decompression. In a kyanite-staurolite-garnet mica schist 300 metres below the metabasites, garnetbearing assemblages grew synchronous with the development of foliations S1 and S2. Garnets are zoned with increasing XMg and decreasing-increasing-rcdecreasing Xca from cores to rims. Albitic plagioclase (An 1-3%) and micas are enclosed in garnet cores and rims, are in contact with garnet, and occur with garnet in microlithons. When these minerals are used for geothermobarometry, a prograde P-T evolution (460 to 680°C with coeval pressure variations which reach high-pressure conditions can be estimated. This suggests that garnet-plagioclase geobarometry with albitic plagioclase works in the relevant P-T field. Similar garnet zonation trends and a similarly shaped P-T path from mica schists of an adjacent region with late-Variscan cooling ages, points to an eady-Variscan age of the syn-D1-D2 high-pressure and subsequent amphibolite-facies metamorphism.

Understanding the environmental and biogeochemical behaviour of radionuclides is essential for managing our nuclear legacy safely. Remediation efforts and the concept of geological disposal of nuclear waste focus on immobilizing radionuclides within the subsurface. Here we review recent developments in the understanding of solid-phase capture processes of Cs, Sr, Tc, U, Pu and Np. Abiotic interactions between minerals and these radionuclides (including sorption, reductive precipitation and co-precipitation) have been studied in various conditions. Microbially driven processes are much less well characterized, for example the effects of microbial reduction on the structure and reactivity of existing minerals, or their role in the formation of new minerals. Metabolites released by bacteria can play a role in both mineral dissolution and formation, and better understanding their release and role in mineralization has great potential in the development of solid-phase capture processes for radionuclides.

With the aid of a map of the research landscape covered by this review (created using a cluster-analysis tool, a self-organizing map), we highlight the most promising sequestration processes for specific radionuclides. However, radionuclides exhibit highly species-specific behaviour in their interactions with minerals and microorganisms. More research is required to characterize the role mineral surfaces play in bioreductive immobilization of Pu and Np, the reduction products formed, and their relative stability. Further studies should concentrate on more environmentally relevant experiments that include bacteria, minerals and radionuclides.

An unusual occurrence of porphyritic plagioclase-hornblende-pyroxene granulite (porphyritic basic charnockite) has been observed within the ‘Charnockite region’ of the Eastern Ghats of the Precambrian formations of India. From the X-ray and chemical data the phenocrysts are considered to be augite phenocrysts. Based on petrographic and chemical evidence it is inferred that the basic charnockites of Chipurupalli area in Visakhapatnam district are formed from tholeiitic magma as a gabbroic mass under deep seated plutonic conditions. The gabbroic mass has been recrystallized as plagioclase-hornblende-pyroxene granulite due to later metamorphism, leaving most of the phenocrysts unaffected.

Petrographic and compositional variations in the Lower Main Zone (LMZ) of the western Bushveld Complex indicate changing regimes of magma replenishment. The lowermost unit of the LMZ, designated N-I, is an enigmatic sequence of leuconoritic cumulates, characterized primarily by up-sequence increases in both orthopyroxene Mg# and whole-rock Sr isotope initial ratio. The Sr isotope profile of N-I is ascribed to injection and progressive integration of small influxes of fresh magma with high (Main Zone-type) Sr isotope initial ratios. The basal Fe-enrichment in N-I, on the other hand, is ascribed to a separate, later mechanism involving the downward migration of late-stage Fe-rich liquids. The overlying two units, N-II and G-I, delineated chiefly in terms of basal Mg-enrichment of orthopyroxene, are ascribed to injections of fresh magma into the chamber. Poikilitic orthopyroxene grains in the basal parts of both N-II and G-I suggest entrainment and partial resorption of plagioclase grains from the semi-crystalline resident material into which the fresh magma was intruded.

Heat flow in SW England is well above average for the UK as a whole, but northwards towards Bath and Bristol the values decrease rapidly. However, hot springs occur both in the Bath-Bristol area and in mines in Cornwall. The development of hydrothermal circulation systems is thus not controlled entirely by geothermal gradient: the presence of a suitable fracture permeability is the main requirement. The thermal ‘head’ produced, which nevertheless depends upon the temperature and volume of water in the system, theoretically can exceed local topographic heads even in areas of low geothermal gradient.

Thermal groundwaters usually carry above average quantities of radioelements in solution because of the long residence times involved. 222Rn values are often particularly high. High concentrations of 222Rn in surface waters arise from the discharge of groundwater. The results of a survey of 222Rn in streams in SW England have established areas of high values which are interpreted as rising limbs of convection cells with dimensions in the order of 5–10 km.

In SE Devon γ-ray spectrometry of soils shows two E.-W. belts of high activity. The northern is coincident with the faulted southern margin of the Crediton Trough, while the southern is coincident with the westerly extension of the Abbotsbury fault system. Groundwater movement along deep-seated fracture systems is considered to be the explanation of these features. The horizontal scale of the area involved suggests that a thermal rather than local topographic head is the driving force. Groundwater circulation within fractures, driven by a thermal head, may therefore occur even in areas of low geothermal gradient and should be considered when selecting waste disposal sites.

More than 19,000 analytical data mainly from the literature were used to study statistically the distribution patterns of F and the oxides of minor and trace elements (Ti, Sn, Sc, V, Cr, Ga, Mn, Co, Ni, Zn, Sr, Ba, Rb, Cs) in trioctahedral micas of the system phlogopite-annite/siderophyllite-polylithionite (PASP), which is divided here into seven varieties, whose compositional ranges are defined by the parameter mgli (= octahedral Mg minus Li). Plots of trace-element contents vs. mgli reveal that the elements form distinct groups according to the configuration of their distribution patterns. Substitution of most of these elements was established as a function of mgli. Micas incorporate the elements in different abundances of up to four orders of magnitude between the concentration highs and lows in micas of ‘normal’ composition. Only Zn, Sr and Sc are poorly correlated to mgli. In compositional extremes, some elements (Zn, Mn, Ba, Sr, Cs, Rb) may be enriched by up to 2–3 orders of magnitude relative to their mean abundance in the respective mica variety. Mica/melt partition coefficients calculated for Variscan granites of the German Erzgebirge demonstrate that trace-element partitioning is strongly dependent on the position of the mica in the PASP system, which has to be considered in petrogenetic modelling.

This review indicates that for a number of trace elements, the concentration ranges are poorly known for some of the mica varieties, as they are for particular host rocks (i.e. igneous rocks of A-type affiliation). The study should help to develop optimal analytical strategies and to provide a tool to distinguish between micas of ‘normal’ and ‘abnormal’ trace-element composition.

Brumadoite, ideally Cu3Te6+O4(OH)4-5H2O, is a new mineral from Pedra Preta mine, Serra das Eguas. Brumado, Bahia, Brazil. It occurs as microcrystalline aggregates both on and, rarely, pseudomorphous after coarse-grained magnesite, associated with mottramite and quartz. Crystals are platy, subhedral. 1—2 μm in size. Brumadoite is blue (near RHS 114B), has a pale blue streak and a vitreous lustre. It is transparent to translucent and does not fluoresce. The empirical formula is (Cu2.90Pb0.04Ca0.01)Σ2.95 (Te0.936+Si0.05)Σ0.98O3.92(OH)3.84.5.24H2O. Infrared spectra clearly show both (OH) and H2O. Microchemical spot tests using a KI solution show that brumadoite has tellurium in the 6+ state. The mineral is monoclinic, P2/m or P21. Unit-cell parameters refined from X-ray powder data are a 8.629(2) Å, b 5.805(2) Å, c 7.654(2) Å,β 0 103.17(2)°, F 373.3(2) Å3, Z= 2. The eight strongest X-ray powder-diffraction lines [d in Å,(I),(hkl)] are: 8.432,(100),(100); 3.162,(66),(2̄02); 2.385,(27),(220); 2.291,(12),(l̄22); 1.916,(11),(312); 1.666,(14),(4̄22,114); 1.452,(10),(323,040); 1.450,(10),(422,403). The name is for the type locality, Brumado, Bahia, Brazil. The new mineral species has been approved by the CNMNC (IMA 2008-028).

Ferromanganese nodules have been recognized widely as potentially important resources for strategic metals. However it remains unclear if the formation of these nodules is purely an abiotic process or if microorganisms are involved in their formation. To determine the microbial contributions, detailed organic geochemical analyses were performed on ferromanganese nodules collected from across the southwest Indian Ocean. These analyses reveal the presence of specific terrestrial, marine and petroleum derived biomarkers, consistent with formation in a marine setting with a substantial influx of terrestrially derived (higher plant detritus) and naturally occurring petroleum-related organic matter. In contrast, only trace amounts of general bacterial biomarkers, commonly present in these types of depositional environments, were present. This indicates that the formation of these ferromanganese nodules is predominantly an abiotic process although a minor contribution from microbial mediated processes to the growth of these nodules cannot be completely ruled out.

Omongwaite, Na2Ca5(SO4)6.3H2O, is a new mineral, found as inclusions in gypsum crystals in recent salt lake deposits at Omongwa pan, Namibia. It is monoclinic, with space group C2, a = 12.08(3) A, b = 6.96(1) Å, c = 6.39(2) Å, B = 90.2(3)°, V= 537(2) Å3, and Z = 1. The six strongest lines in the X-ray powder diffraction pattern [dobs. (Å), (I/I° meas), (hkl)] are: 6.028, (40), (110); 3.484, (29), (310); 3.019, (51), (400); 3.014, (100), (220); 2.824, (34), (1̄12); and 2.820, (65), (112). Electron microprobe analysis, recalculated on the basis of 3H2O per formula unit (p.f.u.), gave 56.16 wt.% SO3, 30.82 wt.% CaO, 5.25 wt.% Na2O, 3.21 wt.% K2O, 6.25 wt.% H2O, totalling 101.69 wt.%. The empirical formula, based on 24 anhydrous oxygens p.f.u., is (Na1.47K0.59)Σ;=2.06Ca4.76S6.07O24.3H2O, yielding Na2Ca5(-SO4)6.3H2O as the end-member formula. Na/K ratios are variable, with an average of ∼2.5. The crystals are elongated, with pseudohexagonal transversal cross-sections and with sphenoidal terminations that are commonly developed at one end. The crystal structure of omongwaite is similar to that of bassanite, CaSO4.0.5H2O. Published studies of the synthetic phase show that it can be described as a bassanite structure in which one out of six Ca2+ ions are replaced by Na+ and a second Na+ ion occupies a position near those sites. The crystals are parallel to the [001] axis of the gypsum crystals in which they occur as inclusions. The mineral formed by topotactic replacement during interaction of gypsum with concentrated solutions. It is preserved where the affected surface became covered by gypsum by rapid growth shortly after the formation of omongwaite. The mineral is named after the locality where it was found.

The type specimen of liskeardite, (Al, Fe)3AsO4(OH)6·5H2O, from the Marke Valley Mine, Liskeard District, Cornwall, has been reinvestigated. The revised composition from electron microprobe analyses and structure refinement is [Al29.2Fe2.8(AsO4)18(OH)42(H2O)22]·52H2O. The crystal structure was determined using synchrotron data collected on a 2 μm diameter fibre at 100 K. Liskeardite has monoclinic symmetry, space group I2, with the unit-cell parameters a = 24.576(5), b = 7.754(2) Å, c = 24.641(5) Å, and β = 90.19(1)º. The structure was refined to R = 0.059 for 9769 reflections with I > 3σ(I). It is of an open framework type in which intersecting polyhedral slabs parallel to (101) and (10) form 17.4 Å × 17.4 Å channels along [010], with water molecules occupying the channels. Small amounts (<1 wt.%) of Na, K and Cu are probably adsorbed at the channel walls The framework comprises columns of pharmacoalumite-type, intergrown with chiral chains of six cis edge-shared octahedra. It can be described in terms of cubic close packing, with vacancies at both the anion and cation sites. The compositional and structural relationships between liskeardite and pharmacoalumite are discussed and a possible mechanism for liskeardite formation is presented.

This paper presents a 27Al and 29Si MAS NMR study of K-feldspars and demonstrates that the spectra are sensitive to variations in the state of Al,Si order. For synthetically annealed samples, the results are in agreement with previous IR spectroscopy (Harris et al., 1989) and demonstrate that Al,Si rearrangement continues after the samples have become monoclinic as determined by powder XRD. NMR methods provide a significantly improved picture of the state of local Al,Si order in such samples. For triclinic samples, measures of the state of Al,Si order (M1 and M2 of 27Al spectra and M2 of 29Si spectra) correlate well with site occupancies determined by powder XRD, but for the monoclinic samples the NMR parameters continue to change whereas the XRD parameters do not. Interpretations based on the NMR results for the synthetically disordered samples are consistent with 1-step disordering, as observed by XRD. 27Al and 29Si MAS NMR is likely to be a useful tool for probing the state of local Al,Si order in a wide variety of natural samples.

The kinetics and mechanisms of dissolution of the major base metal sulphide minerals, pyrite, chalcopyrite, galena and sphalerite in acidic (chloride) media have been investigated. Minerals were ground in air, then dissolved in air-equilibrated solutions at pH 2.5, while monitoring the redox potential. Solution samples were analysed by ICP-AES and HPLC, and surfaces of residual sulphides analysed using XPS. Dissolution of aerial oxidation products on pyrite particles in the first 15 min apparently led to a sulphur-rich surface, and was followed by slower dissolution of pyrite itself, driven by oxygen reduction, and resulting in net production of protons. Chalcopyrite dissolution resulted in a Cu, S-rich (near) surface layer, accompanied by net consumption of protons. Apparently incongruent dissolution of galena and sphalerite may reflect the formation of elemental S at the surface. The rates of dissolution of chalcopyrite, galena and sphalerite in the presence of pyrite were determined, respectively, as 18, 31 and 1.5 times more rapid than in single-mineral experiments. These data were consistent with galvanically-promoted mineral oxidation of the other sulphides in the presence of pyrite. In the case of galena, the experimental data suggested extensive release of Pb ions and development of a sulphur-rich surface during galvanically-promoted dissolution.