The Freetown Intrusion, Sierra Leone, evolved by recurrent injection of olivine-bearing magma producing an aggregate thickness greater than 6000 m of rhythmically layered rocks. Sedimentation and constrained viscous flow of crystallizing magma concentrated olivine crystals during initial formation whilst concentration of volatiles locally lowered residual melt temperatures. This affected the crystallization of pyroxenes especially in pyroxene-troctolites where abundance of olivine caused deferred pyroxene growth. Three examples are described: (1) Flattened and elongated schlieren of augite enclosing plagioclase in ophitic intergrowths show preferred orientation cutting across primary layering defined by olivine, proving that pyroxene growth was secondary and influenced by stress directions in a relatively rigid rock. (2) In some pyroxene-troctolites, augite is segregated into coarse ophitic nodules which are widely and evenly spaced in a troctolitic host rock. Successful pyroxene nucleation and extensive diffusion caused development of domains of equilibration within a ‘cotectic’ pyroxene-plagioclase-volatile system. Crystallization within this was deferred compared with the surrounding olivine-plagioclase assemblage in which effects of granulitization are conspicuous. (3) Occasionally the pyroxenes are segregated in dispersed lenticular bodies of noritic pegmatite in troctolite. As in the previous cases, growth of pyroxene involved resorption and regrowth of olivine. This reflects the highest temperatures of crystallization in equilibrium with volatile-enriched pegmatite fluids. Temperatures decreased inwards giving a zonal structure and late growth of biotite, orthoclase, and apatite.

The formation of late crystalline pyroxenes and pegmatites thus involved extensive diffusion of volatile and other components accompanying the establishment of domains of reduced pressure in hot and slowly cooled rocks subjected to gradual deformation due to progressive subsidence of the central parts of the intrusion. The final fabric is therefore metamorphic resulting from annealing rather than crystal accumulation.

Extensive studies on oriented reactions in the system MnO-O-H2O have revealed surprising symmetry changes, which we have been unable to explain. Orientation relationships are often complicated, but where interpretation is possible, the results support the idea that orientations are controlled by the oxygen frame-work and that considerable migration of manganese occurs.

Ion imaging by SIMS (ion microprobe) techniques provides a novel approach to the identification of mechanisms of fluid-mineral interaction during hydrothermal experiments. In scanning ion imaging, the primary ion beam is focussed to a fine spot which is rastered across the polished sample surface, and the secondary ion signal from the mass spectrometer is synchronised with the primary beam. The resistive anode encoder provides a direct ion image of a sample surface illuminated by a defocussed primary beam. The latter system is susceptible to charging artifacts during the imaging of insulating geological materials, and has a lower dynamic range than the scanning ion imaging system.

Application of both systems to the study of fluid–mineral interaction during hydrothermal experiments are reviewed in which fluid or solid phases have been labelled with 18O-enriched isotopic tracers. These include studies of micropermeability and microporosity in feldspars, solid-state diffusion versus solution-reprecipitation, textural equilibration mechanisms, and oxygen isotope exchange in silicate–carbonate systems.

Deveroite-(Ce), ideally Ce2(C2O4)3·10H2O, is a new mineral (IMA 2013-003) found in the alpine fissures of Mount Cervandone, overlooking the Devero Valley, Piedmont, Italy. It occurs as sprays of colourless elongated tabular, acicular prisms only on cervandonite-(Ce). It has a white streak, a vitreous lustre, is not fluorescent and has a hardness of 2–2.5 (Mohs' scale). The tenacity is brittle and the crystals have a perfect cleavage along {010}. The calculated density is 2.352 g/cm3. Deveroite-(Ce) is biaxial (–) with 2V of ∼77°, is not pleochroic and the extinction angle (β ∧ c) is ∼27°. No twinning was observed. Electron microprobe analyses gave the following chemical formula: (Ce1.01Nd0.33La0.32Pr0.11Y0.11Sm0.01Pb0.04U0.03Th0.01Ca0.04)2.01(C2O4)2.99·9.99H2O. Although synchrotron radiation was not used to solve the structure of deveroite-(Ce) the extremely small size of the sample (13 μm × 3 μm × 1 μm) did not allow us to obtain reliable structural data. However, it was possible to determine the space group (monoclinic, P21/c) and the unit-cell parameters, which are: a = 11.240(8) Å, b = 9.635(11) Å, c = 10.339(12) Å, β = 114.41(10)°, V = 1019.6 Å3. The strongest lines in the powder diffraction pattern [d in Å (I)(hkl)] are: 10.266(100)(100); 4.816(35.26)(21); 3.415(27.83)(300); 5.125(24.70)(200); and 4.988(22.98)(111). Deveroite-(Ce) is named in recognition of Devero valley and Devero Natural Park.

Uroxite (IMA2018-100), [(UO2)2(C2O4)(OH)2(H2O)2]⋅H2O, and metauroxite (IMA2019-030), (UO2)2(C2O4)(OH)2(H2O)2, are the first two uranyl oxalate minerals. Uroxite was found in the Markey mine, Red Canyon, San Juan County, Utah, USA and in the Burro mine, Slick Rock district, San Miguel County, Colorado, USA. Metauroxite was found only in the Burro mine. Both minerals are post-mining secondary phases found in efflorescent crusts on mine walls. Uroxite occurs as light yellow striated blades exhibiting moderate neon-green fluorescence, ca 2 Mohs hardness with good {101} and {010} cleavages. Calculated density = 4.187 g/cm3. Optics are: biaxial (–), α = 1.602(2), β = 1.660(2), γ = 1.680(2) (white light), 2Vmeas. = 59(1)°, 2Vcalc = 59.1°, moderate r > v dispersion, orientation Y = b, Z ∧ a = 35° in obtuse β and it is nonpleochroic. Metauroxite occurs as light yellow crude blades and tablets exhibiting weak green–grey fluorescence, ca 2 Mohs hardness with good {001} cleavage. Calculated density = 4.403 g/cm3. Approximate optics are: α′ = 1.615(5) and γ′ = 1.685(5). Electron probe microanalysis provided UO3 79.60, C2O3 10.02, H2O 10.03, total 99.65 wt.% for uroxite and UO3 82.66, C2O3 10.40, H2O 7.81, total 100.87 wt.% for metauroxite; C2O3 and H2O are based on the structures. Uroxite is monoclinic, P21/c, a = 5.5698(2), b = 15.2877(6), c = 13.3724(9) Å, β = 94.015(7)°, V = 1135.86(10) Å3 and Z = 4. Metauroxite is triclinic, P${\bar 1}$, a = 5.5635(3), b = 6.1152(4), c = 7.8283(4) Å, α = 85.572(5), β = 89.340(4), γ = 82.468°, V = 263.25(3) Å3 and Z = 1. The strongest reflections of the powder XRD pattern [d, Å (I, %)(hkl)] are for uroxite: 10.05(38)(011), 5.00(100)(022, ${\bar 1}$11), 4.75(23)(031), 4.43(51)(120, ${\bar 1}$02), 3.567(33)(131), 3.341(29)(033, ${\bar 1}$32, 004), 2.623(28)(${\bar 2}$02, 015, ${\bar 1}$43, 220) and for metauroxite: 6.06(45)(010), 5.52(33)(100), 4.97(34)(011), 4.52(100)(0${\bar 1}$1, 101), 3.888(80)(111, 002, ${\bar 1}$10), 3.180(51)(${\bar 1}$02, 0${\bar 1}$2), 2.604(32)(${\bar 2}$01, ${\bar 1}$${\bar 2}$1). In the structure of uroxite (R1 = 0.0333 for 2081 I > 2σI reflections), UO7 pentagonal bipyramids share corners forming [U4O24] tetramers, which are linked by C2O4 groups to form corrugated sheets. In the structure of metauroxite (R1 = 0.0648 for 1602 I > 2σI reflections) UO7 pentagonal bipyramids share edges forming [U2O12] dimers, which are linked by C2O4 groups to form zigzag chains.

Oxides of the Cu-Fe-O system prepared by solid-state reaction methods have been investigated by X-ray, Mössbauer effect, and analytical chemical techniques. In agreement with most previous investigations of this system, it is found that CuFeO2 exists as a stable compound, and that the mineral delafossite has essentially this composition. These results are in disagreement with those of Buist, Gadalla, and White who propose that delafossite has an approximate composition Cu6Fe3O7 instead of CuFeO2. In fact, a compound of composition Cu6F3O7 could not be prepared. The Mössbauer isomer shift provides confirmation that the iron in CuFeO2 is trivalent.

The Tertiary volcano-sedimentary sequence of the Feres basin (Thrace, NE Greece), includes lavas of andesitic–rhyolitic composition as well as volcaniclastic rocks, pyroclastic flows and pyroclastic fall deposits principally of dacitic–rhyodacitic composition. The pyroclastic flow deposits frequently show intense devitrification, vapour-phase crystallization and evidence of fumarolic activity, which involves deposition of scapolite in pore spaces. The Feres basin can be subdivided on the basis of mineral alteration assemblages: (1) the Pefka region; characterized by intense hydrothermal alteration of the volcanic rocks and mineral zoning(silicic, argillic, sericitic and propylitic zones) with polymetallic mineralization, and (2) the remainder of the basin; where the volcaniclastic rocks are characterized by the alteration of volcanic glass to zeolites (clinoptilolite, heulandite, mordenite, analcime), clay minerals (smectite, illite, celadonite, chlorite), SiO2 polymorphs (cristobalite, opal-CT, quartz), K-feldspar and calcite. Laumontite is also present as an alteration product of plagioclase, with stilbite sporadically occurringin veinlets. Locally, rhyolites are also altered to zeolites (clinoptilolite and/or mordenite). The zeolitization process has occurred rapidly with the depositional environment, temperature, rate of cooling(of the volcanic rocks), nature and temperature of the mineral-forming fluids and composition of the parent material controllingthe formation of zeolites.

The ultrastructures of parisite-(Ce) from a rare-earth mineral deposit of Sichuan Province, southwest China, have been observed and investigated by selected area electron diffraction (SAED) and high resolution electron microscopy (HREM). Six new polytypes 4H, 10H, 16H, 18R, 24R and 30R were determined in parisite-(Ce), as were their crystal structure types, subcell (a′c‴, a′c″, a′c′) and supercell (ac) parameters, reflection conditions, polytype features and probable space groups. The HREM studies revealed the complex polytypism in parisite-(Ce) whereby the six new polytypes, formed by long-period ordered stacking, always coexist with the common polytype parisite-(Ce)-6R by syntaxy and thus constitute the complex microstructural ‘syntactic polycrystals’, the host of which is the polytype parisite-(Ce)-6R.

Quantitative electronprobe microanalyses have been made of stannite from various localities. It was found that in general this mineral corresponds in composition to the formula Cu2FeSnS4. However, noticeable deviations in the ratio of the metals can occur and considerable concentrations of zinc may be present.

Some tin minerals related to stannite have also been analysed, namely hexastannite, mawsonite, and an apparently hitherto unknown mineral to which the name rhodostannite is given.

A magmatic calcic amphibole (M4Ca≥1.50) characterized by large Sr and F contents (SrO>1 wt.%, F>2.5 wt.%) is described. According to the crystal-chemical formula, the amphibole can be classified as a strontian fluoro-magnesiohastingsite and the presence of Sr cations in the A sites is suggested. The amphibole occurs in the groundmass of ultrapotassic lavas from the Alban Hills Volcanic District (Central Italy). This peculiar chemical composition is due to the lavas' groundmass compositional trend occurring under low silica-activity conditions. We suggest that the occurrence of F amphiboles allows us to consider the Alban Hills Volcanic District magmas to be as rich in F as other ultrapotassic magmas.

Native palladium is rare and occurs in oxidizing environments (hematite stability field) and consistently has very low contents of other metals. On the other hand, gold may contain significant amounts of alloyed palladium. A nugget of palladian gold, obtained from a specularite-rich auriferous vein (‘jacutinga’) of the Gongo Soco iron ore mine, Quadrilátero Ferrífero, Minas Gerais, allows the definition of a paragenetic sequence of native palladium formation. The cm-sized nugget is brecciated and consists of fragments of palladian gold [Au0.79Pd0.09Cu0.07Ag0.04Hg0.01] with inclusions of isomertieite [Pd11Sb2As2], cemented by kaolinite-hematite-palladian gold infill. The isomertieite inclusions are preferentially fractured and display various degrees of alteration to a Pd-O phase. Native palladium occurs as a crystallized component within the Pd-O phase, with microstructural and chemical features suggesting a desiccation process. It is proposed that native palladium forms by (1) oxidation of a pre-existent palladium mineral to a Pd-O phase, and (2) subsequent crystallization of native palladium from the Pd-O phase, by oxygen loss and dehydration. This process operates in a low-temperature hydrothermal or weathering environment and leads to strong fractionation of palladium and gold.

Girdite, H2Pb3(TeO3)TeO6 is white, H = 2, D = 5.5. Crystals are complexly twinned and appear monoclinic domatic. The X-ray cell is a = 6.241Å, b = 5.686, c = 8.719, β = 91°41′; Z = 1.

Oboyerite is H6Pb6(TeO3)3(TeO6)2 · 2H2O. H = 1.5, D = 6.4. Crystals appear to be triclinic but are too small for X-ray work.

Fairbankite PbTeO3 is triclinic a = 7.81Å, b = 7.11, c = 6.96, α = 117°12′, β = 93°47′, γ = 93°24′, Z = 4. Indices are α = 2.29, β = 2.31, γ = 2.33.

Winstanleyite, TiTe3O8, is cubic Ia3, a = 10.963Å. Crystals are cubes, sometimes modified by the octahedron; colour Chinese yellow, H = 4, nD = 2.34.

All of the above species were found in small amounts on the waste dumps of the Grand Central mine, Tombstone, Arizona, associated with a wealth of other tellurites and tellurates.

Hematophanite, ideally Pb4Fe3O8Cl, is tetragonal, space group P4mm, with a = 3·92 and c = 15·31 Å. The crystal structure, which has been refined to an R-factor of 9·1 %, may be described as an interlayering of perovskite-like units with a cesium chloride or, alternatively, a nadoritelike unit. The nadorite-like part consists of a double layer of PbO4Cl4 distorted square antiprisms. Iron atoms are in 6-fold (tetragonal bipyramidal) and 5-fold (square pyramidal) coordination.

Three-dimensional counter-diffractometer data and a full-matrix least-squares method have been used to refine the crystal structure of a ferrotschermakite in the space group C2/m. The chemical composition of the amphibole is with cell parameters a 9·8179(7), b 18·1060(14), c 5·3314(5) Å, and β 105·00(I). Cation site-occupancies were initially assigned by ionic-radius criteria and refined with the constraint that the sum total of the site-occupancies be equal to the chemical analysis.

The A-site shows positional and substitutional disorder and can be better represented by two sites, one on the mirror plane and the other on the 2-fold axis.

Unit weights were used throughout the refinement and the final R-factor for 1207 observed nonequivalent reflections was 4·5 %.

This study provides the first detailed mineralogical data on platinum-group element (PGE) mineralization of the Waterberg Project, in a previously unknown segment of the Bushveld Complex located in the Southern Marginal Zone of the Limpopo Belt. The lower ultramafic F zone is dominated by sperrylite (up to 82 area%) with minor Pt–Pd bismuthotellurides, Pd–Ni arsenides, Au–Ag alloy, Rh–Pt sulfoarsenides and rare Pt–Fe alloys. The upper more felsic-rich gabbroic T zone is dominated by Pt–Pd bismuthotellurides (up to 90 area%), Pd tellurides and Au–Ag alloy with rare sperrylite, braggite, Pd stannides and antimonides. The platinum-group minerals (PGM) of the F zone are associated mainly with magmatic base-metal sulfides (pyrrhotite, troilite, chalcopyrite and pentlandite), that have undergone alteration during significant serpentinization, accompanied by the formation of the secondary sulfide assemblage. The T zone in a leucogabbroic sequence contains relics of magmatic sulfides and is characterized by the development of the indicative chalcopyrite-millerite-pyrite assemblage, which is associated with widespread hydrothermal quartz and hydrous silicates (amphiboles, phlogopite, epidote and chlorite). The fluid-induced style of PGM remobilization, the high Au/PGE and the high proportion of native gold in the high-grade T zone ores in the magnetite-bearing leucogabbroic rocks are unique to the Bushveld Complex. The genesis of the T ores is interpreted as a result of primary PGE enrichment in the zone of interaction between the first influxes of the Upper Zone fertile melt and a resident gabbroic melt at the top of the Troctolite-Gabbronorite-Anorthosite (TGA) fractionated sequence with subsequent fluid remobilization. Whether the hydrothermal overprint facilitated the PGE sequestration in a favourable setting or dispersed the pre-existing magmatic concentrations along fluid pathways remains essentially unresolved at the current stage.

Glaukosphaerite, a new secondary basic copper-nickel carbonate was first determined and described from Widgiemooltha (31° 30′ S., 121° 34′ E.), Western Australia, by R. C. Morris at the W.A. Government Chemical Laboratories in 1967. The mineral has since been found at the nickel mines at Kambalda, Windarra, Scotia, Carr Boyd Rocks, and St. Ives, Western Australia, and is apparently an indicator of copper-nickel sulphide mineralization. The name is derived from the colour and spherulitic formation. Associated minerals are goethite, secondary quartz, paratacamite, gypsum, nickeloan varieties of magnesite and malachite, and clays. Glaukosphaerite also fills joints in fresh basic rocks.

The type material is from Hampton East Location 48, 3 km N. of the Durkin Shaft, Kambalda. Glaukosphaerite is monoclinic, a 9·34 Å, b 11·93 Å, c 3·07 Å, β 90–1°, space group indeterminate, c axis disordered, six strongest X-ray powder lines are 2·587 (10b) 201, 3·68(7b) 220, 2·516(4) 240, 211, 5·04(3) 120, 2·124(3b), 1·473(3). The mineral occurs in green spherules of fibres cleaved and elongated along c, D = 3·78 to 3·96 increasing with Cu, is brittle, H. 3 to 4, and has dull to subvitreous to silky lustre.

α 1·69–1·71 green, β ≈ γ 1·83–1·85 yellow-green, α:[001] 7°.

Chemical analysis on the type material, D 3·78, containing 0·5 % goethite impurity and minimal inseparable malachite, gave CuO 41·57, NiO 25·22, CoO 0·07, ZnO 0·02, Fe2O3 0·47, MgO 1·23, SiO2 < 0·01, CO2 21·70, H2O+ 9·85, H2O− < 0·01, sum 100·13%. After deduction of goethite the unit cell contains 4[(Cu,Ni,Mg,Co)1.74C0·96H2·12O4·73]. This unit-cell content is deficient in metal ions and oxygen and contains excess H, when compared to 4[(Cu,Ni)2(OH)2CO3]. Two analyses of malachite-bearing glaukosphaerite from Widgiemooltha and Carr Boyd Rocks show the same deficiencies and excess not previously recorded in malachite, rosasite, or aurichalcite analyses. Glaukosphaerite, 4[(Cu,Ni)2(OH)2CO3] is the nickel analogue of rosasite 4[(Cu,Zn)2(OH)2CO3].

From results based on X-ray rotation patterns of oriented rosasite fibres from Sardinia and Durango with supplementary electron-microprobe studies and Guinier powder-film data, the authors consider glaukosphaerite and rosasite to be separate mineral species from the related malachite, 4[Cu2(OH)2CO3].

Type material is preserved in the government collection at the Government Chemical Laboratories, Perth, Western Australia.

Two samples of hydrotalcite, probably worked on by Carl Christian Hochstetter, have been discovered in the Museum für Naturkunde Berlin and given neotype status by the IMA CNMNC (proposal 15-J). The two samples from Snarum, Norway, have been reanalysed and give Mg5.84Al2.07Fe0.09(OH)16(CO3)1.08·4H2O and Mg5.75Al2.21Fe0.04(OH)16(CO3)1.12·4H2O. Both samples have a mix of the two polytypes 3R/2H in the ratio of 69.2/30.8 and 69.5/30.5%. A discussion of hydrotalcite and hydrotalcite-like phase occurrences in the literature is also presented.

During a study of the ore minerals belonging to the recently discovered Shuangjianzishan Ag–Pb–Zn deposit in NE China, we have discovered exceptional selenium enrichment in canfieldite (up to 11.6 wt.% of Se). Incorporation of Se into canfieldite has been investigated by an integrated approach using field emission scanning electron microscopy, electron microprobe and single-crystal X-ray diffraction. Canfieldite has been identified as one of the dominant Ag-bearing ore minerals in the studied deposit, which occurs mostly in slate-hosted vein type Ag–Pb–Zn ore bodies. Selenium is either homogeneously or, remarkably, heterogeneously distributed in the different canfieldite fragments studied. Chemical variations of Se are mostly attributable to a series of retrograde reactions resulting in diverse decomposition and exsolution of primary phases during cooling, or alternatively, related to influxes of Se-rich fluids during the formation of canfieldite. To evaluate the effects of the Se-for-S substitution in the structure, a crystal of Se-rich canfieldite [Ag7.98Sn1.02(S4.19Se1.81)Σ6.00] was investigated. The unit-cell parameters are: a = 10.8145(8) Å and V = 1264.8(3) Å3. The structure was refined in the space group F$\bar{4}$3m to R1 = 0.0315 for 194 independent reflections, with 20 parameters. The crystal structure of Se-rich canfieldite was found to be topologically identical to that of pure canfieldite. If the short Ag–Ag contacts are ignored (due to the disorder), the two Ag atoms in the structure can be considered as three-fold (Ag1) and four-fold (Ag2) coordinated. Tin adopts a regular tetrahedral coordination. As in the case of Te-rich canfieldite, the refinement of the site-occupancy factor indicates that Se is disordered over the three anion positions.

There exists in the Lake District a peculiar type of metamorphism of which no analogue has, as far as the writer is aware, been described elsewhere, with the exception, perhaps, of South America. It is indicated chiefly by the presence of garnets and 'streaks ', the former being found indifferently in every variety of igneous rock of the district, the latter being mainly confined to the rhyolites or quartzkeratophyres. The most similar known to the writer is at Oyacachi in Ecuador, whence veto Rath has described flow-brecciated soda-rhyolites which sometimes contain red garnets. He also refers to rocks which may be 'streaky'.