During the course of a detailed X-ray study of chrysotile, antigorite, and gümbelite by E. Aruja we were asked to confirm some interesting results he had obtained on heating chrysotile to various temperatures. This we were able to do and also to provide additional data which were recently referred to in a paper by A. Hargreaves and W. H. Taylor. Although we have not succeeded in providing a completely satisfactory explanation of the optical changes observed on heating chrysotile our observations for a limited range of temperatures in the neighbourhood of 1000° C. are here recorded.

The compound Li2Zr(WO4)3 has been synthesized. It has the monoclinic wolframite-type structure with cell dimensions a 4·78Å, b 5·70 Å, c 4·96 Å, and β 92° 10′. The univalent and tetravalent cations are randomly arranged in the divalent cation sites in the wolframite-type lattice.

The old mine Settlingstones, situated three miles north of Haydon Bridge in the county of Northumberland, was originally worked as a lead mine, but, during the htst fifty years, as the vein has been explored farther west, it has attained far greater importance as the largest and most consistent producer of witherite in the British Isles. The Settlingstones main vein has a direction approximately north-east and southwest, and has been proved for a distance of nearly 1½ miles. The vein has varied in width from 3 feet up to 40 feet, the most productive witherite-bearing portion averaging 10 to 12 feet. The enclosing rocks are sandstones ('whetstones') and shales ('plate') of Carboniferous age, and dolerite (Whin-sil) which here attains a thickness of a little over 21 fathoms.

A very fine and unusual crystal of sperrylite, recently presented by Mr. G. H. Beatty of Johannesburg to the mineral collection of the British Museum, came from a new adit on the Tweefontein farm (no. 1083), about 10 miles NNW. of Potgietersrust, Waterberg district, Transvaal. It had been found embedded in copper-stained limonite in crush-zones of banded ironstone underlying norite. The limonite matrix is presumably an alteration-product of sulphides (pyrrhotine, pentlandite, and chalcopyrite). The banded ironstone is an altered sediment belonging to the dolomite series, and is penetrated by apophyses from the basic margin of the Bushveld igneous complex.

The behaviour of tin under varying circumstances has frequently attracted the attention of chemists, and several authors have concluded that it is capable of assuming at least two different crystallographic forms, only one of which, however, has been thoroughly investigated. Since Miller described the beautiful pyramidal crystals of tin obtained by galvanic deposition from a solution of its protochloride, the anomalous appearance of those obtained in the dry way has often been remarked upon. Brooke obtained octagonal needles on slowly cooling molten tin and pouring off the fluid part. Pajot in a similar manner obtained rhombic prisms. Stolba obtained quadratic plates, whilst Breithaupt saw tin crystals, from Cornish smelting furnaces, which had the form of short hexagonal prisms (Miller considered them to be Cu Sn2). Lastly Rammelsberg inferred from the varying specific gravity that a not yet determined dimorphic form existed.

Wiklundite, ideally Pb2[4](Mn2+,Zn)3(Fe3+,Mn2+)2(Mn2+,Mg)19(As3+O3)2[(Si,As5+)O4]6(OH)18Cl6, isa new arseno-silicate mineral from Långban, Filipstad, Värmland, Sweden. Both the mineral and the name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA 2015-057). Wiklundite and a disordered wiklundite-like mineral form radiating, sheaf-like aggregates (up to 1 mm long) of thin brownish-red and slightly bent lath-shaped crystals. It occurs in a dolomite-rich skarn in association with tephroite, mimetite, turneaurite, johnbaumite, jacobsite, barite, native lead, filipstadite andparwelite. Wiklundite is reddish brown to dark brown, and the streak is pale yellowish brown. The lustre is resinous to sub-metallic, almost somewhat bronzy, and wiklundite does not fluoresce under ultraviolet light. The calculated density is 4.072 g cm–3. Wiklundite is brittle with an irregular fracture, and has perfect cleavage on {001}; no parting or twinning was observed. Wiklundite is uniaxial (–), orange red and non-pleochroic in transmitted light, but shows incomplete extinction and distorted interference figures, preventing complete determination of optical properties. Electron-microprobe analysis (H2O calculated from the structure) of wiklundite gave SiO2 11.17, Al2O3 0.06, Fe2O3 4.46, As2O5 0.75, As2O3 6.81, MnO 47.89, ZnO 0.78,CaO 0.09, PbO 14.48, Cl 6.65, H2O 5.18, O=Cl2 –1.50, total 97.11 wt.%, As valences and H2O content taken from the crystal-structure refinement, and Fe3+/(Fe2+ + Fe3+) determined by Mössbauer spectroscopy. Wiklundite is hexagonal-rhombohedral, space group R3c, a = 8.257(2), c = 126.59(4) Å, V = 7474(6) Å3, Z = 6. The crystal structure of wiklundite was solved by direct methods and refined to a final R1 index of 3.2%. The structure consists of a stacking of five layers of polyhedra: three layers consist of trimers of edge-sharing Mn2+-dominant octahedra linked by (SiO4) tetrahedra, (Fe3+(OH)6) dominant octahedra and (AsO3) triangular pyramids; one layerof corner-sharing (SiO4) and (Mn2+O4) tetrahedra; and one layer of (Mn2+Cl6) octahedra and (Pb2+(OH)3Cl6) polyhedra. The mineral is named after Markus Wiklund (b. 1969) and Stefan Wiklund (b. 1972), the well-known Swedish mineral collectors who jointly found the specimen containing the mineral.

Aqueous chemistry methods assessed the kinetic reactivity and reduction capacity of fracture-filling minerals from a granitic groundwater environment at the Aspo Hard Rock Laboratory, a field station for research and development into the geological disposal of spent nuclear fuel. Naturally occurring fracture filling reacted with oxygenated test solutions of known composition in recirculating batch reactors.

The loss of O2(aq) with time was consistent with second-order reaction kinetics where O2(aq) is consumed through reduction by reaction with structural Fe(II) at the surface of the fracture minerals. Values of the second-order rate constant (k, l mole—1 h—1) varied between experiments within the range 1.7 < log k < 2.9 and values for the total concentration of reducing sites as a measure of the reduction capacity of the mineral (St, mole g—1) varied within the range 8.5 x 10—5 < St < 4.3 x 10—4. Values for the rate constant are somewhat less than those published previously for reaction between O2(aq) and Fe(II) surface complexes; i.e. structural Fe(II) appears to be less reactive than adsorbed Fe(II)(aq) but is significantly more reactive than Fe2+.

Values of the rate constant did not depend on release of network ions from the reacting minerals, and did not vary significantly with pH, mineral mass, specific surface area or mineral Fe(II) content. Oxidative weathering of sulphide minerals does not occur to any measurable extent. When corrected to rock/water ratios for granite aquifers, the rate constants correspond to a half-life for O2(aq) on the order of seconds indicating an essentially instantaneous reaction on repository time scales. Comparison of reducing capacity for the fracture fillings and oxidizing capacity for groundwater saturated with O2(aq) indicates that oxidizing fronts within the geological barrier would travel ~4000 times more slowly than the velocity of groundwater flow.

Ferroan and non-ferroan calcites occur in fractures in the Lower Carboniferous of the Variscan foreland of southern Belgium. These fractures post-date the Variscan orogeny and the calcites have a telogenetic origin. The non-ferroan calcites formed by recrystallization of the ferroan calcites. Two types of monophase aqueous fluid inclusions are present in the ferroan calcite cement. Although both types of inclusions formed at a temperature not exceeding 50°C, one type contains a moderately saline fluid (3.6–16.3 eq. wt.% NaCl) and the other type fresh water (Tm ice = 0°C). The fluid inclusions in the non-ferroan calcite also contain fresh water.

Detailed petrography of the fluid inclusions indicate that the fresh water migrated through the crystals along opened cleavage planes and microfractures. Therefore, they have a secondary origin. The recrystallization of the ferroan calcites to non-ferroan calcites occurred in this fresh water. The saline fluid inclusions are not related to the above mentioned microstructures and although their origin remains unknown, they could represent the ambient fluid from which the ferroan calcites precipitated. The study of the relationship between the occurrence of fluid inclusions and the microstructures seems promising for the identification of fluid inclusions representing post mineral formation fluid and temperature conditions in calcite cements.

Dyrnaesite-(La), Na7.89(Ce0.94Ca0.06)∑1.00(La1.14Ce0.40Pr0.10Nd0.24Ca0.12)∑2.00(PO4)6 is orthorhombic, Pnma, a = 18.4662(7), b= 16.0106(5), c = 7.0274(2) Å, V = 2077.7(1) Å3, Z = 4. The crystal structure is related to the group of Na3REE(XO4)2 compounds (with X = P, V, As), based on the aphthitalite/glaserite structural type. Dyrnaesite is distinct in having ordered Na vacancies, and a rare-earth element (REE) site occupied preferentially by Ce4+. This also distinguishes it from closely related vitusite-(Ce) [Na3REE(PO4)2]. The relation of their unit cells is: ad= bv, bd = 3av, cd = 1/2 cv. The distinct Ce4+ site in dyrnaesite-(La) has smaller coordination with shorter bond lengths than the other REE site in the same structure or the REE sites in vitusite-(Ce). It is adjacent to the predominately vacant Na site, which in its turn has the largest coordination of all Na sites in the structure. REE sites, or Na sites in a [010] row (similar to [100] in vitusite(Ce)) assume two types of coordinations with and without mirror symmetry and two different configurations of surrounding PO4 tetrahedra. This summarizes the topological difference to vitusite-(Ce) where the corresponding coordinations are similar in the same row and intermediate in character to the two types in dyrnaesite-(La).

A new analysis of the violet amphibole from the original locality where winchite came from agrees with another recent analysis in differing substantially from the original winchite composition and is (K0·17Na2·10Ca0·23)(Al0·19Ti0·00Fe31·27Fe20·01Mn0·07Mg3·34)Si8·01O22·05(OH)1·95. It is essentially a magnesio-arfvedsonite. Although it is possible that the original analysis was unreliable, evidence is given to support the alternative view that there is a wide range of blue alkali and soda calcic amphibole compositions at Kajlidongri and the name winchite should be restricted to compositions between ferri-winchite CaNaMg5Fe3+Si8O22(OH,F,Cl)2 and alumino-winchite CaNaMg5Al Si8O22(OH,F,Cl)2. X-ray, density, and optical data on the analysed mineral are given.

The new alluaudite-group mineral paraberzeliite was found in the Arsenatnaya fumarole, Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. In the deepest zone of Arsenatnaya, paraberzeliite (holotype) is associated with anhydrite, diopside, hematite, svabite, berzeliite, schäferite, calciojohillerite, magnesioferrite, ludwigite, fluorapatite, powellite, baryte, and rhabdoborite-group and aphthitalite-group members. In the middle zone of the fumarole, paraberzeliite occurs with hematite, calciojohillerite, badalovite, johillerite, nickenichite, tilasite, svabite, fluorophlogopite, sanidine, cassiterite, anhydrite, metathénardite and belomarinaite. Paraberzeliite forms prismatic crystals up to 0.2 mm × 0.2 mm × 1 mm often occurring in open-work aggregates. It is transparent, brown (from light to dark brown, sometimes with purple or red hue) or green (from pale greenish to yellow–green). The mineral is brittle, cleavage was not observed. The Mohs hardness is 3½. Dcalc is 3.811 g cm–3. Paraberzeliite is optically biaxial (+), α = 1.718(4), β = 1.728(4), γ = 1.742(4) and 2Vmeas. = 85(5)°. The chemical composition (wt.%, electron-microprobe; holotype) is: Na2O 6.43, CaO 16.65, MgO 11.64, MnO 1.65, CuO 0.06, Fe2O3 2.45, V2O5 1.10, As2O5 59.46, total 99.44. The calculated empirical formula based on 12 O atoms per formula unit is (Na1.20Ca1.71Mg1.66Mn0.13Fe3+0.18)Σ4.88(As2.98V0.07)Σ3.05O12. Paraberzeliite is monoclinic, C2/c, a = 12.3143(7), b = 13.0679(5), c = 6.7717(4) Å, β = 113.657(7)°, V = 998.14(10) Å3 and Z = 4. The crystal structure was solved from single-crystal X-ray diffraction data, R = 0.0349. Paraberzeliite is isostructural with other alluaudite-group minerals. Its simplified crystal chemical formula is A(1)CaA(2)'NaM(1)CaM(2)Mg2(TAsO4)3. The idealised formula is NaCa2Mg2(AsO4)3, or, according to the actual nomenclature of alluaudite-group arsenates, NaCaCaMg2(AsO4)3. The name paraberzeliite reflects the dimorphism of this alluaudite-group mineral with the arsenate garnet berzeliite, ideally (Ca2Na)Mg2(AsO4)3.

Svetlanaite, SnSe is a new mineral discovered from the high-sulfidation epithermal Au-deposit Ozernovskoe, Kamchatka peninsula, Russia. It forms tiny euhedral spindles (0.5–2 μm × 10–15 μm) in quartz, in close association with cassiterite, rutile, mohite, mawsonite, kiddcreekite, hemusite, tellurium, kostovite and Se-bearing ‘fahlores’ (Se-goldfieldite–Se(Bi)-tetrahedrite–Se-tennantite). In plane-polarised light, svetlanaite is light-grey, pleochroic from white to cream and strongly anisotropic in shades of light blue, dark blue, khaki and orange–brown; it exhibits no internal reflections. Reflectance values of synthetic analogue of svetlanaite in air (R1,R2 in %) are: 50.9, 56.5 at 470 nm, 50.2, 56.7 at 546 nm, 49.5, 55.3 at 589 nm and 48.7, 53.4 at 650 nm. Twelve electron-microprobe analyses of svetlanaite give an average composition: Sn 61.30, Se 37.22 and S 1.25 total 99.79 wt.%, corresponding to the empirical formula Sn1.01(Se0.92S0.07)Σ0.99 based on 2 atoms; the average of seven analyses on its synthetic analogue is: Sn 59.98 and Se 39.71, total 99.59 wt.%, corresponding to Sn1.00Se1.00. The density, calculated on the basis of the empirical formula, is 6.08 g/cm3. The mineral is orthorhombic, space group Pnma, with a = 11.500(2), b = 4.154(2), c = 4.445(2) Å, V = 212.34(14) Å3 and Z = 4. The crystal structure was solved and refined from the powder X-ray-diffraction data of synthetic SnSe. It crystallises in the GeS-structure type. It is isostructural with the mineral herzenbergite (SnS). The mineral name is in honour of Svetlana K. Smirnova, a Russian mineralogist, for her contributions to geology in the epithermal Au–Ag deposits of the Tien–Shan region.

New chemical (EMP, SIMS) and structural data are reported for a suite of crystals of oxo-mangani-leakeite and mangano-mangani-ungarettiite from their common type locality, the Hoskins mine (New South Wales, Australia). Notwithstanding the low OH content, FTIR analysis of selected sampleshas provided considerable information on short-range order in these Mn3+-rich amphiboles, and shows that Li is associated with occupied A sites and is linked to the oxo-component at the O(3) site. Comparative analysis of all available data allows us to: (1) further improveour understanding of the crystal-chemistry of these very peculiar compositions of the oxo-amphibole group; and (2) calculate reliable site-populations. The proposed limited compositional variability has been confirmed. The two amphiboles have completely different arrangements of CR3+cations. In oxo-mangani-leakeites, those CR3+ cations related to the oxocomponent occur at the M (1) site, whereas those CR3+ cations related to the leakeite charge-arrangement occur at the M (2) site. In mangano-mangani-ungarettiite,all CR3+ cations order at the M (1) and M (3) sites, and local bond-valence requirements are satisfied by the presence of Mn3+, which assumes a strongly distorted coordination due to its degenerate eg electronic state. Therefore,the inverse patterns observed for both cation-ordering and deformation of the octahedra are incompatible with solid-solution between these two species that coexist at the Hoskins mine.

Carlosbarbosaite, ideally (UO2)2Nb2O6(OH)2·2H2O, is a new mineral which occurs as a late cavity filling in albite in the Jaguaraçu pegmatite, Jaguaraçu municipality, Minas Gerais, Brazil. The name honours Carlos do Prado Barbosa (1917–2003). Carlosbarbosaite forms long flattened lath-like crystals with a very simple orthorhombic morphology. The crystals are elongated along [001] and flattened on (100); they are up to 120 μm long and 2–5 μm thick. The colour is cream to pale yellow, the streak yellowish white and the lustre vitreous. The mineral is transparent (as individual crystals) to translucent (massive). It is not fluorescent under either long-wave or short-wave ultraviolet radiation. Carlosbarbosaite is biaxial(+) with α = 1.760(5), β = 1.775(5), γ = 1.795(5), 2Vmeas. = 70(1)º, 2Vcalc. = 83º. The orientation is X || a, Y || b, Z || c. Pleochroism is weak, in yellowish green shades, which are most intense in the Z direction. Two samples were analysed. For sample 1, the composition is: UO3 54.52, CaO 2.07, Ce2O3 0.33, Nd2O3 0.49, Nb2O5 14.11, Ta2O5 15.25, TiO2 2.20, SiO2 2.14, Fe2O3 1.08, Al2O3 0.73, H2O (calc.) 11.49, total 104.41 wt.%; the empirical formula is (□0.68Ca0.28Nd0.02Ce0.02)Σ=1.00[U1.44□0.56O2.88(H2O)1.12](Nb0.80Ta0.52Si0.27Ti0.21Al0.11Fe0.10)Σ=2.01 O4.72(OH)3.20(H2O)2.08. For sample 2, the composition is: UO3 41.83, CaO 2.10, Ce2O3 0.31, Nd2O3 1.12, Nb2 O5 14.64, Ta2O5 16.34, TiO2 0.95, SiO2 3.55, Fe2O3 0.89, Al2O3 0.71, H2O (calc.) 14.99, total 97.43 wt.%; the empirical formula is (□0.67Ca0.27Nd0.05Ce0.01)Σ=1.00[U1.04□0.96O2.08(H2O)1.92] (Nb0.79Ta0.53Si0.42Ti0.08Al0.10Fe0.08)Σ=2.00O4.00(OH)3.96(H2O)2.04. The ideal endmember formula is (UO2)2Nb2O6(OH)2·2H2O. Calculated densities are 4.713 g cm-3 (sample 1) and 4.172 g cm-3 (sample 2). Infrared spectra show that both (OH) and H2O are present. The strongest eight X-ray powder-diffraction lines [listed as d in Å (I)(hkl)] are: 8.405(8)(110), 7.081(10)(200), 4.201(9)(220), 3.333(6)(202), 3.053(8)(022), 2.931(7)(420), 2.803(6)(222) and 2.589(5)(040,402). The crystal structure was solved using single-crystal X-ray diffraction (R = 0.037) which gave the following data: orthorhombic, Cmcm, a = 14.150(6), b = 10.395(4), c = 7.529(3) Å, V = 1107(1) Å3, Z = 4. The crystal structure contains a single U site with an appreciable deficiency in electron scattering, which is populated by U atoms and vacancies. The U site is surrounded by seven O atoms in a pentagonal bipyramidal arrangement. The Nb site is coordinated by four O atoms and two OH groups in an octahedral arrangement. The half-occupied tunnel Ca site is coordinated by four O atoms and four H2O groups. Octahedrally coordinated Nb polyhedra share edges and corners to form Nb2O6(OH)2 double chains, and edge-sharing pentagonal bipyramidal U polyhedra form UO5 chains. The Nb2O6(OH)2 and UO5 chains share edges to form an open U—Nb—φ framework with tunnels along [001] that contain Ca(H2O)4 clusters. Carlosbarbosaite is closely related to a family of synthetic U–Nb–ϕ framework tunnel structures, it differs in that is has an (OH)-bearing framework and Ca(H2O)4 tunnel occupant. The structure of carlosbarbosaite resembles that of holfertite.

The occurrence of coexisting paragonite (containing 0·70 % CaO) and muscovite (containing 0·16 % CaO) in a staurolite-grade paragonite-muscovite-hornblende-garnet-biotite schist from Sulitjelma enables an estimate to be made of the temperature of recrystallization, using an extension, based on crystal chemistry considerations and available analyses of muscovites and paragonites from metamorphic rocks, of the experimentally determined solvus in the K-Na white mica system into the Ca-K-Na system. This temperature of recrystallization is approximately 550–70 °C and is consistent with the experimental data on the coexistence of staurolite and quartz in the system Fe-A1-Si-O-H (Richardson, 1968).

In the Gåsborn area, West Bergslagen, central Sweden, Mn-silicate-magnetite-jacobsite skarns were formed as the result of three successive processes. (1) Deposition of exhalative-sedimentary manganiferous iron-ore-bearing sediments together with cherts and volcanics. (2) Intrusion of a synvolcanic anorogenic granite and some slightly younger gabbros and tonalites: under influence of these intrusives the manganiferous iron-ore-bearing sediments were metamorphosed into (a) rhodonite(I)-magnetite-pyrophanite-garnet assemblages; (b) (manganiferous) hedenbergite(I)-allanite-titanite-garnet-magnetite assemblages; (c) tephroite-jacobsite-pyrophanite-garnet assemblages and (d) magnetite-bearing quartzites. (3) Release of hydrothermal fluids from the granite and subsequent alteration of the above assemblages into metasomatic infiltration skarns, consisting of rhodonite(II), garnet, hedenbergite(II), biotite, actinolite or edenite (with up to 20.11 wt.% MnO), chlorite, bementite, fluorite, helvite, rhodochrosite, hematite, rutile and accessory galena, sphalerite, wittichenite, aikinite, pyrrhotite, chalcopyrite and pyrite.

The maximum temperature (T) and pressure (P) during contact metamorphism are estimated at 550°C and 1.0 kbar respectively. The fluid under influence of which the metasomatic infiltration skarns were formed was relatively rich in Fe, Cl and F and carried little or no Mg and Mn.

During early diagenesis (beginning of stage 2) fo2 was between the hematite/magnetite (hm/mt) and the hausmannite + hematite = jacobsite buffers (h + m = j). During stage 2, with increasing T, fo2 changed from above to below hm/mt. Magnetite and jacobsite at some distance from the hydrothermal veins from which the metasomatic skarn-forming fluids were released, were altered during stage 3 into hematite. Magnetite in, and close to the hydrothermal veins was not altered to hematite, implying an increase in fo2 to above hm/mt with increasing distance from these veins.

The chemical analyses, structural formulae, and optical data of seven orthopyroxenes and six clinopyroxenes, all from the charnockite series of Amaravathi, are presented. The orthopyroxenes are in the hypersthene-ferrohypersthene range while the clinopyroxenes are in the sahlite range. The aluminous nature of the pyroxene is believed to be the result of high pressure. The clinopyroxenes have the granulite trend on the Wo-En-Fs plot. The tie-line projections and the KD values for the pyroxene pairs indicate conditions of chemical equilibrium around 670 °C for the charnockite series of Amaravathi.