A third world occurrence of rouxelite, ideally Cu2HgPb22Sb28S64(O,S)2, has been identified from the baryte-pyrite-Fe oxides ore of Monte Arsiccio mine, near Sant’Anna di Stazzema (Apuan Alps, Tuscany, Italy). Rouxelite occurs as mm-sized acicular crystals, black in colour, with bluish-violet iridescence, in vugs of carbonate + baryte + quartz veins embedded in dolostones from the Sant’Olga tunnel. It is associated with Tl-bearing chovanite, sphalerite and valentinite. Its X-ray powder diffraction pattern gives unit-cell parameters a = 43.10(2), b = 4.060(2), c = 37.88(2) Å, β = 117.33(2)°, V = 5889(5) Å3. Electron-microprobe data reveal a complex chemistry, with additional minor elements (wt.%): Tl (0.6–1.7), Ag (0.4–0.6), As (0.2–0.6) and Bi (≤0.05). This indicates a widespread substitution of Hg by Ag, according to Hg + Pb = Ag + Sb and incorporation of Tl, with some Ag, according to 2Pb = Sb + (Tl, Ag). The occurrence of mixed (Hg, Ag) and (Hg, Cu) sites in natural sulfides and sulfosalts is briefly reviewed. The Tl-content of the samples studied is a characteristic fingerprint agreeing with the Tl-rich nature of the mineral assemblage from Monte Arsiccio. Rouxelite therefore constitutes a new example of a Tl-bearing sulfosalt.

Rinkite-(Y), ideally Na2Ca4YTi(Si2O7)2OF3, is a new rinkite-group (seidozerite-supergroup) TS-block mineral from the Darai-Pioz alkaline massif, Tian-Shan mountains, Tajikistan. The mineral is of hydrothermal origin. It occurs as aggregates (up to 1.5 cm long) of acicular crystals 0.1–1.0 mm thick, and as separate elongated columnar, flattened-prismatic crystals up to 1 cm long with rectangular or rhombic sections up to 0.5 mm across. Associated minerals are quartz, aegirine, microcline, neptunite, pectolite, calcite, eudialyte-group minerals, fluorite, titanite, turkestanite, kupletskite, galena, albite and pyrochlore-group minerals. Crystals are transparent and colourless to occasionally white, with a vitreous lustre. Rinkite-(Y) has a white streak, uneven, conchoidal fracture and does not fluoresce under a cathode or ultraviolet light. Cleavage is very good on {100}, no parting was observed, Mohs hardness is ~5, and it is brittle, Dmeas. = 3.44(2) g/cm3, Dcalc. = 3.475 g/cm3. It is biaxial (+) with refractive indices (λ = 590 nm) α = 1.662(2), β = 1.666(2), γ = 1.685(5); 2Vmeas. = 50(3) and 2Vcalc. = 49.7°. It is nonpleochroic. Rinkite-(Y) is monoclinic, space group P21/c, a = 7.3934(5), b = 5.6347(4), c = 18.713(1) Å, β = 101.415(2)° and V = 764.2(2) Å3. The six strongest reflections in the X-ray powder diffraction data [d(Å), I, (hkl)] are: 3.057, 100, (006, $\bar{2}$12, 210); 2.688, 28, (016); 9.18, 24, (002); 2.929, 17, ($\bar{2}$13, 211); 3.559, 15, (104, 014) and 2.783, 14, (021). The empirical formula calculated on 18 (O + F) is Na2.11(Ca3.74Sr0.03Mn0.03)Σ3.80(Y0.50Nd0.16Ce0.16Gd0.07Dy0.06Sm0.05Pr0.03La0.03${\rm U}_{0.01}^{{\rm 4 + }} {\rm )}_{\Sigma 1.07}{\rm (T}{\rm i}_{0.85}{\rm N}{\rm b}_{0.17}{\rm W}^{6+}_{0.01}{\rm T}{\rm a}_{0.01}{\rm )}_{\Sigma 1.04}\left( {{\rm S}{\rm i}_{4.03}{\rm O}_{14}} \right){\rm O}_{1.40}{\rm F}_{2.60}$ with Z = 2. The ideal formula is Na2Ca4YTi(Si2O7)2OF3. The crystal structure was refined on a twinned crystal to R1 = 4.59% on the basis of 1489 unique reflections (F > 4σF) and is a framework of TS (Titanium-Silicate) blocks. The TS block consists of HOH sheets (H – heteropolyhedral, O – octahedral) parallel to (100). In the O sheet, the Ti-dominant [6]MO1 site ideally gives 1 Ti apfu. The [8]MO2 and [6]MO3 sites are ideally occupied by Na and (NaCa) apfu. In the H sheet, the [7]MH site is occupied by Ca1.13Y0.50REE0.37, (REE = rare-earth element), ideally (CaY), <MH–φ> = 2.415 Å and the [7]AP site is occupied by Ca1.81REE0.19, ideally Ca2, <AP–φ> = 2.458 Å. The MH + AP sites ideally give (Ca3Y) apfu. The MH and AP polyhedra and Si2O7 groups constitute the H sheet. Linkage of H and O sheets via common vertices of MH and AP polyhedra and Si2O7 groups with MO1–3 polyhedra results in a TS block. The TS block in rinkite-(Y) exhibits linkage 1 and stereochemistry typical for the rinkite group (Ti = 1 apfu) of the seidozerite supergroup. For rinkite-(Y), the ideal structural formula of the form AP2MH2MO4(Si2O7)2$ \left( {{\rm X}_{\rm M}^{\rm O} } \right)_2\left( {{\rm X}_{\rm A}^{\rm O} } \right)_2{\rm is }\;\left( {{\rm C}{\rm a}_3{\rm Y}} \right){\rm Na}\left( {{\rm NaCa}} \right){\rm Ti}\left( {{\rm S}{\rm i}_2{\rm O}_7} \right)_2\left( {{\rm OF}} \right){\rm F}_2 $ with Z = 2. The mineral is named rinkite-(Y) as it is structurally identical to rinkite-(Ce) and Y is the dominant rare-earth element.

An ideal solution model has been used to calculate the effect of the substitutions on the stability fields of the Al2SiO5 minerals. The results show that divariant assemblages of andalusite+sillimanite and sillimanite + kyanite solid solutions can coexist over ranges of 0·1 to 0·4 kbar at 527° C, but that kyanite+andalusite would be stable over a much narrower range. On adding (Fe, Mn)3+ to the system, the andalusite/sillimanite curve can be considered to rotate about the invariant point, first eliminating the sillimanite field, and then penetrating the kyanite field. Wide zones of viridine+sillimanite and viridine+kyanite are thus formed.

In view of the ease with which epitaxial nucleation occurs in the Al2SiO5 system, it is considered that extensive metastable growth of andalusite, sillimanite, and kyanite is improbable in nature. Metastable persistence is likely to occur in dry systems, or in the presence of an ‘armour’ of the stable phase, but reaction of millimetre-sized crystals should be completed in geologically short times when aqueous or silicate liquids are present. The combination of the effects of metastable persistence and solid solution seems adequate to account for essentially all the examples of kyanite + sillimanite and kyanite + andalusite, and for many sillimanite +andalusite assemblages. In addition, if small supersaturations develop during metamorphism, simultaneous growth of andalusite + sillimanite could occur over a restricted temperature range.

Five turquoise samples, belonging to the XVII century historical collection of the Real Museo Mineralogico (University of Naples Federico II), were investigated by a multi-methodological approach based on powder X-ray diffraction, electron microprobe analysis in wavelength-dispersive spectroscopy mode, backscattered electron images from scanning electron microscopy in energy-dispersive spectroscopy mode, laser ablation inductively coupled plasma mass spectrometry, Fourier transform infrared and Raman spectroscopy.

The samples originate from Sinai (Egypt), Santa Fè S. Miguel (New Mexico), Saxony (Germany), Montebras Creuse (France) and Nishapur (Khorassan, Iran) and display different mineralogical compositions and various mineral associations. The study has shown the presence of: (1) four minerals of the turquoise group: turquoise, faustite, chalcosiderite and planerite; (2) other phosphates from different groups: wavellite, crandallite, goyazite, gorceixite, variscite, metavariscite, fluorapatite; and (3) other minerals: voltaite, adularia and quartz.

The present investigation is intended to show the mineralogical and geochemical variability of the samples with particular attention to the mineralogical parageneses, textural analyses and trace-element concentrations.

Granular aggregates of fine-grained graftonite (Fe,Mn,Ca)3(PO4)2 and intergrown wolfeite (Fe,Mn)2(PO4)(OH) occur in amphibolite-facies metamorphosed iron formations associated with the Gamsberg Zn-Pb deposit, South Africa. To date, these minerals were believed to have limited parageneses, being essentially restricted to granitic pegmatites and iron meteorites. This paper is the first report of the occurrence of graftonite and wolfeite in a regionally metamorphosed, iron formation-hosted setting. The aggregates are found together with Mn- and Pb-rich apatite and calcian pyromorphite in a pristine unit of almost pure chemical precipitates, the origin of which is intimately linked to the base-metal mineralizing process. Evidence from Gamsberg supports previous studies conducted on pegmatite-hosted graftonites that a simple host rock mineralogy and geochemical prerequisites, such as high activities of Fe, Mn, Ca and a deficiency in F, exert a dominant control on the stabilization of these minerals. However, in a marine sedimentary environment, significant concentrations of phosphorus have to be precipitated to prevent stabilization of all the phosphorus as fluorapatite. The paucity of graftonite in such settings suggests that the combination of these requirements is only rarely achieved.

Arsenopyrite (FeAsS), gudmundite (FeSbS) and the rarer Fe sulfosalts berthierite (FeSb2S4) and garavellite (FeSbBiS4), were investigated by Raman spectroscopy. Whereas (Sb,Bi)S3 pyramids are responsible for the Raman spectra of berthierite and garavellite, the spectra of gudmundite and arsenopyrite arise from the stretching and bending modes of (Sb,As)S units. Internal vibrations for berthierite and garavellite occur between 400 and 50 cm–1, and those of the gudmundite and arsenopyrite between 500 and 100 cm–1. The longer bond distances of the SbS3 groups readily explain the lower frequencies for berthierite in comparison with garavellite. Similarly, the greater mass and the longer bond distances of the Sb–S units also explain the lower frequencies observed for gudmundite relative to arsenopyrite.

This study presents a complete characterization of kenoplumbomicrolite, (Pb,□)2Ta2O6[□,(OH),O], occurring in an amazonite pegmatite from Ploskaya Mountain, Western Keivy Massif, Kola Peninsula, Murmanskaja Oblast, Northern Region, Russia.

Kenoplumbomicrolite occurs in yellowish brown octahedral, cuboctahedral and massive crystals, up to 20 cm, has a white streak, a greasy lustre and is translucent. The Mohs hardness is ~6. Attempts to measure density (7.310–7.832 g/cm3) were affected by the ubiquitous presence of uraninite inclusions. Reflectance values were measured in air and immersed in oil. Kenoplumbocrolite is optically isotropic. The empirical formula is (Pb1.30□0.30Ca0.29Na0.08U0.03)Σ2.00(Ta0.82Nb0.62Si0.23Sn4+0.15Ti0.07Fe3+0.10Al0.01)Σ2.00O6[□0.52(OH)0.25O0.23]Σ1.00 (from the crystal used for the structural study) and (Pb1.33□0.66Mn0.01)Σ2.00(Ta0.87Nb0.72Sn4+0.18Fe3+0.11W0.08Ti0.04)Σ2.00O6[□0.80(OH)0.10O0.10]Σ1.00 (average including additional fragments). The mineral is cubic, space group Fd$\overline 3 $m. The unit-cell parameters refined from powder X-ray diffraction data are a = 10.575(2) Å and V = 1182.6(8) Å3, which are in accord with those obtained previously from a single crystal of a = 10.571(1) Å, V = 1181.3(2) Å3 and Z = 8. The mineral description and its name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2015-007a).

Grunerite asbestos (var. amosite) from Penge, Transvaal, contains lamellae consisting of multiple-chain I-beams which frequently terminate within the structure. Such terminations may be either coherent or incoherent, the latter involving disturbances of the structure akin to dislocations. These may be of the nature of edge dislocations or of dislocations having both edge and screw components.

Models are presented which have been used to elucidate the structural disturbances associated with the termination and side-stepping of multiple-chain lamellae. Odd-multiple-chains are shown to be of particular significance in giving rise to dislocations with a screw component along the c-axis.

Synthesis of Ni and Zn substituted nano-greigite, Fe3S4, is achieved from single source diethyldithiocarbamato precursor compounds, producing particles typically 50–100 nm in diameter with plate-like pseudohexagonal morphologies. Up to 12 wt.% Ni is incorporated into the greigite structure, and there is evidence that Zn is also incorporated but Co is not substituted into the lattice. The Fe L3 X-ray absorption spectra for these materials have a narrow single peak at 707.7 eV and the resulting main X-ray magnetic circular dichroism (XMCD) has the same sign at 708.75 eV. All XMCD spectra also have a broad positive feature at 711 eV, a characteristic of covalent mixing. The greigite XMCD spectra contrast with the three clearly defined XMCD site specific peaks found in the ferrite spinel, magnetite. The Fe L2,3X-ray absorption spectra and XMCD spectra of the greigite reflect and reveal the high conductivity of greigite and the very strong covalency of the Fe–S bonding. The electron hopping between Fe3+ and Fe2+ on octahedral sites results in an intermediate oxidation state of the Fe in the Oh site of Fe2.5+ producing an effective formula of [Fe3+ ↑]A-site[2Fe2.5+ ↓]B-siteS42–]. The Ni L2,3 X-ray absorption spectra and XMCD reveal substitution on the Oh site with a strongly covalent character and an oxidation state <Ni1.5+ in a representative formula [Fe3+ ↑]A[[(2 – x)Fe2.5+ ↓][Nix1.5+]]BS42–.

Manganoan ilvaite forms as an early retrograde metamorphic phase from calcic rhodonite in the polymetamorphosed Pb-Zn sulphide/manganese silicate rocks at Broken Hill and from grossular-andradite in a skarn at Ban Ban. Ilvaite exists as a probable metastable phase into which Mn is apparently strongly partitioned. The manganoan ilvaites analysed contain up to 13·5 % MnO substituting for FeO and this substitution shifts the 020 peak.

Among the many beautiful rocks of Unst, the most northerly of the Shetlands, is one composed of rosettes of pale blue kyanite set in a base of glassy quartz. This rock was mentioned by Heddle, but has never been described, nor have its genetic relationships been considered. During the mapping of Unst for the Geological Survey, opportunity was afforded of examining the field-relations of these quartz-kyanite-rocks and of collecting adequate material for study. I am indebted to Sir John Flett, F.R.S., Director of the Survey, for permission to present this account. These rocks have a considerable intrinsic interest; in addition, their investigation is closely concerned with certain general problems in metamorphism, especially those connected with metamorphic differentiation. The present paper is therefore divided into two portions, the first dealing with the description and origin of the Unst rocks, and the second with more general aspects.

New Pd-Tl-(Bi,As)-rich compounds are described from the Anomal'nyi Cu-PGE deposit, Kondyor alkaline ultramafic complex, northeastern Russia. They occur in vein-type settings associated with bodies of 'kosvite' (magnetite-rich clinopyroxenite) in the dunite-(peridotite) core, in pegmatiticand micaceous rocks. The ore zones are substantially enriched in phlogopite; they consist of diopside, disseminated titaniferous magnetite and fluorapatite (Sr-bearing). The observed assemblages of ore minerals include sulfides of the chalcopyrite-bornite-(secondary chalcocite) associationand various species of platinum-group minerals (PGM) [isomertieite or arsenopalladinite rich in Sb, mertieite-II, mertieite-I, sobolevskite, kotulskite, merenskyite, zvyagintsevite, palarstanide, paolovite, sperrylite, maslovite or moncheite, hollingworthite and unnamed species of PGM] anda Ag-Au alloy. The oxides [Pd4(Bi,Te,Tl)O6 and Pd4(Tl,Bi,Te)O6] probably formed in situ by oxidation reactions at the expense of the associated PGM intergrowths. These involve palladium bismuthide-thallide phases, Pd5(Tl,As,Bi)and Pd5(As,Tl,Bi), which are documented here for the first time. A fairly evolved environment, enriched in Cu, Pd, Te, Bi, Pb and volatile components, is indicated for the vein-type deposit at Anomal'nyi.

The new mineral alwilkinsite-(Y) (IMA2015-097), Y(H2O)7[(UO2)3(SO4)2O(OH)3]·7H2O, was found in the Blue Lizard mine, San Juan County, Utah, USA, where it occurs as a secondary alteration phase.The mineral is slightly flexible before brittle failure with splintery fracture and perfect cleavage parallel to [010], has Mohs hardness of ∼2–2½, exhibits dull greenish-grey fluorescence and has a calculated density of 3.371 g cm–3. Alwilkinsite-(Y) occursas yellowish-green needles, elongate on [010], with domatic terminations and exhibits the forms {102}, {301} and {124}. It is optically biaxial (+) with α = 1.573(1), β = 1.581(1), γ = 1.601(1) (white light), the measured 2V is 65.3(1)°, the dispersion is r<v (weak), the optical orientation is X = c, Y = a, Z = b and there is no pleochroism. Electron microprobe analyses yielded the empirical formula (Y0.66Dy0.08Gd0.06Er0.05Nd0.03Yb0.03Sm0.02Ce0.01)∑0.94(H2O)7[(UO2)3(S1.01O4)2O(OH)3]·7H2O.The eight strongest powder X-ray diffraction lines are [dobs Å(I)(hkl)]: 9.88(100)(101,002), 7.47(13)(102), 5.621(17)(103,201), 4.483(18)(104), 3.886(14)(130,222), 3.322(46)(multiple), 3.223(13)(multiple) and 3.145(16)(034). Alwilkinsite-(Y) is orthorhombic,P212121, a = 11.6194(5), b = 12.4250(6), c = 19.4495(14) Å, V = 2807.9(3) Å3 and Z = 4. The structure of alwilkinsite-(Y) (R1 = 0.042 for 4244 Fo > 4σF)contains edge-sharing chains of uranyl bipyramids with outlying sulfate tetrahedra that are similar to the chain linkages within the uranyl sulfate sheets of the zippeite structure. Short segments of the uranyl sulfate chains in the alwilkinsite-(Y) structure have the same topology as portionsof the uranyl sulfate linkages in uranopilite. Alwilkinsite-(Y) is named for Alan (Al) J. Wilkins, MD (born 1955), the discoverer of the mineral.

Nine ferrohastingsites from the Younger Granites of Northern Nigeria and five from the nepheline-bearing rocks in the Marangudzi complex of Southern Rhodesia have been analysed chemically and their optical properties and unit-cell parameters determined.

All the minerals have compositions that can be expressed by the formula NaCa2(Fe″Mg)4Fe‴Al2Si6O22(OH)2, but the Nigerian minerals differ from those of Marangudzi in their lower alumina contents, generally greater degree of iron enrichment, lower potassium, and more variable fluorine contents. These differences are considered to reflect the differences in composition of their respective parent rocks. The compositional similarities between some hastingsites and barkevikite are commented upon and the pleochroism of barkevikite is briefly discussed.

Refractive indices of the analysed hastingsites have been plotted on the optical curves of Tröger. It is suggested that such curves are of limited use and that variations in unit-cell parameters might be a more useful method of determining the iron contents of hastingsites.

The variation in cell parameters with variation in chemical composition of the analysed minerals is also discussed.

In the UK, most intermediate level radioactive waste is packaged in stainless steel containers. It is important that containers should maintain their integrity for extended periods of storage prior to final disposal. A prototype 4 metre box fabricated from 304S11 stainless steel was monitored at an inland rural building for over twelve years to gain experience in monitoring environmental conditions and corrosion during storage. A wide range of different types of aerosol particles were observed on the surfaces and in the air. They contained corrosive ions such as chloride, as well as other anions such as sulfate and nitrate. The chloride deposition rate was between 0.1 and 4 μg cm−2 yr−1 depending on the orientation and location of the surface, with a chloride/sulfate ratio ranging from ∼0.3–2. The temperature and relative humidity typically ranged from 0–30°C and 40–90%, respectively. The greatest degree of corrosion developed on the base of the box, which had elevated chloride concentrations (10–140 μg cm−2). However, there was little evidence of corrosion propagation on the surface of the box and no evidence of stress corrosion cracking. The average pit propagation rates on a 316L coupon mounted next to the 4 m box were <1 μm yr−1.

A review is given of the metallurgical literature relating to the formation of metal rodeutectics, which are texturally similar to myrmekite. Since no satisfactory explanation for rodeutectics has been advanced, a comparison is made with myrmekite. It is proposed that this intergrowth develops as a result of the constriction of quartz during its recrystallization and inclusion in an expanding blastic growth of plagioclase, and the forces involved lead to the prolongation along the growth directions of quartz in the form of rods with a relatively small surface area (i.e. with circular cross-sections). Possible forces that could produce the same geometry in metal intergrowths are those that result from the relative contractions of the two components during freezing; in all cases for which quantitative data are known, the metallic rods have a greater contraction on freezing than the host substance. Examples of myrmekite and myrmekite-like intergrowths in the Constant Gneiss are described in relation to their particular origin. Two factors, the lack of proportionality of qtartz to feldspar and the intimate association of myrmekite with myrmekite-like intergrowths, support the proposed mechanism of constriction of pre-existing quartz.

The metamorphic history of the Mesoarchean Amikoq Layered Complex within the Akia terrane of SW Greenland was characterised by electron microprobe mineral data and detailed petrography on 12 representative samples, integrated with zircon U–Pb geochronology and petrology. The complex intruded into a >3004 Ma supracrustal association now consisting of granoblastic metabasites with subordinate quartz-rich gneiss. Supracrustal host rocks contain a relict high-temperature assemblage of orthopyroxene–clinopyroxene (± pigeonite exsolution lamellae, exsolved at ~975–1010°C), which is interpreted to pre-date the Amikoq intrusion. Cumulate to granoblastic-textured rocks of the main Amikoq Layered Complex range modally from leuconorite to melanorite, orthopyroxenite to harzburgite/dunite and rare hornblende melagabbro. Observed mineralogy of main complex noritic lithologies is essentially relict igneous with orthopyroxene–biotite and hornblende–plagioclase thermometers yielding temperatures of ~800–1070°C. An anatectic zircon megacryst from a patchy quartzo–feldspathic leucosome hosted in an orthopyroxene-dominated Amikoq rock reflects local anatexis at peak metamorphic P–T conditions and yields an intrusion minimum age of 3004 ± 9 Ma. Field observations indicate local anatexis of orthopyroxene-dominated lithologies, possibly indicating a post-intrusion peak temperature of >900°C. The last preserved stages of retrogression are recorded in paragneiss plagioclase–garnet, biotite–garnet and host rock ilmenite–magnetite pairs (≤3 kbar and ~380–560°C).

The Amikoq Complex intruded a MORB-like crustal section and the former remained relatively undisturbed in terms of modal mineralogy. Preservation of igneous textures and mineralogy are related to an anhydrous, high-grade metamorphic history that essentially mimics igneous crystallisation conditions, whereas local high-strain zones acted as fluid pathways resulting in hydrous breakdown of igneous minerals. There is no evidence of equilibration of the intrusion at sub-amphibolite-facies conditions.

The principal data are collected about the fall and the distribution of the fragments of the Siena, Italy, meteorite (11·6°E., 43·1°N.). A complete individual, weighing 110·55 g, is described in some detail. Crust morphology, mineralogical composition, and structure were studied. Optical data were established by microscopical analysis and both thin and polished sections were observed. Compared with available electron-probe analysis they are found in good agreement. The chemical analysis is Fe 12·93, Ni 1·39, Co 0·09, FeS 5·46, SiO2 37·10, TiO2 0·14, Al2O3, 3·91 FeO 11·46, MnO 0·35, MgO 23·81, CaO 1·63, Na2O 0·90, K2O 0·16, P2O5 0·44, H2O+ 0·10, H2O− 0·00, Cr2O3 0·56, total 100·43. Siena is an ordinary chondrite, with relatively ambiguous characteristics and evident features of recrystallization and metamorphism.