Chlorine is estimated in nine hornblendes (0·13–1·12%) and nine biotites (0·19–0·62%) from the Kondapalli charnockites for the first time, using the electron microprobe. The data obtained suggest that these Kondapalli minerals are unexpectedly and unusually rich in Cl, which is well equilibrated in the five available coexisting hornblende-biotite pairs.

The crystal structure of Fe2SiO4 spinel at room temperature was investigated at seven different pressures by X-ray diffraction, using a diamond anvil cell to examine the influence of Fe substitution on ringwoodite behaviour at high pressure. The results compared with those of a pure Mg endmember show that the substitution of Fe into the spinel structure causes only small changes in the compression rate of coordination polyhedra and the distortion of the octahedron. The data show that the compression rate for the octahedron and tetrahedron in (Mg,Fe)2SiO4 can be considered statistically equal for FeO6 and MgO6, as well as for SiO4 in both the endmembers. This shows why almost identical bulk moduli are reported along the solid solution in recent literature.

Criddleite, ideally TlAg2Au3Sb10S10, is a rare constituent within the Hemlo gold deposit, Hemlo, Ontario, Canada. The mineral occurs as 20 to 50 µm-sized lath-like, tabular or anhedral grains usually surrounding or penetrating aurostibite, or associated with native antimony, native gold and stibnite. Criddleite is opaque with a metallic lustre and a black streak. It has been synthesized by reacting TlSbS2 and high purity Ag, Au, Sb and S in an evacuated silica glass tube at 400 °C. The measured density of the synthetic material is 6.86; the calculated density is 6.57 g/cm3. The difference is due to minor admixed aurostibite, native antimony and a dyscrasite-like phase within the charge. VHN25 is 94–129. Mohs hardness (calc.) = 3–3 ½. In reflected plane-polarized light in air, natural criddleite is weakly bireflectant with a discernible reflectance pleochroism from grey-blue to slightly greenish grey-blue. The mineral has a distinct to moderate anisotropy with rotation tints in shades of buff to slate grey. Reflectance spectra and colour values for both natural and synthetic criddleite are given. X-ray study showed that synthetic criddleite is monoclinic (pseudotetragonal) with refined unit-cell parameters a = 20.015(2), b = 8.075(2), c = 7.831(2) Å, β = 92.01(2)°, V = 1264.9 ± 1.0 Å3 and a:b:c = 2.4786: 1:0.9698. The space group choices are A2/m(12), A2(5) or Am(8), diffraction aspect A*/*. The seven strongest lines in the X-ray powder diffraction pattern [d in Å (I) (hkl)] are: 5.63(90) (011), 3.91(50) (002), 3.456(50) (320), 2.860(70) (700), 2.813(100) (022), 2.018(60) (040) and 1.959(70) (004). Electron microprobe analyses are reported of natural criddleite in five polished sections of drill core from four holes. The averaged empirical formulae, based on 26 atoms, are Tl0.92Ag1.99Au2.93Sb9.87S10.28 (natural) and Tl0.94Ag2.03Au2.89Sb9.76S10.38 (synthetic).

High-alumina subsilicic calcic amphiboles, including sadanagaite and subsilicic ferroan pargasite, are found in rock samples from the contact aureole in the Nōgō-Hakusan area, central Japan. They occur in the reaction zones between dark fragments and the surrounding crystalline limestone of the pyroxene hornfels facies zone. The dark fragments which underwent K-metasomatism are originally basaltic rocks. The sadanagaite and subsilicic ferroan pargasite have high Al2O3 (16–19 wt. %) and K2O (3.6–4.3 wt. %) contents. The Si value ranges from 5.38 to 5.64 and the total Al ranges from 3.10 to 3.43 when cation ratios are calculated on the basis of O = 23. The calculated unit cell parameters of sadanagaite are a 10.00 (1), b 18.06 (2), c 5.355 (4) Å, β105.52(7)°, V 932(1) Å3. The A-sites of the amphiboles is occupied almost entirely by K and Na; the amphiboles are saturated with the edenite component. The amphiboles show a larger extent of tschermakite-type substitution [(Mg,Fe)Si⇌AlAl] than does ordinary pargasite. Sadanagaite is probably stable at the temperature above the upper amphibolite facies.

Watanabeite Cu4(As,Sb)2S5, in which As>Sb, is a new copper sulphosalt that occurs with quartz in a hydrothermal vein at the Teine mine, Sapporo, Hokkaido, Japan. It is silvery lead-grey in colour with lead-grey streak. VHN100 = 253-306 kg/mm2, brittle. It has no cleavage and the fracture is uneven. The measured density = 4.66(2) g/cm3. The mean of six microprobe analyses gave Cu 41.1, Ag 0.1, Mn 0.3, As 15.4, Sb 14.3, Bi 2.4, S 26.2, a total of 99.8 wt.%, corresponding to: (Cu3.94Mn0.03− Ag0.01)∑3.98(As1.25Sb0.72Bi0.07)∑2.04S4.98 (basis: total atoms = 11), or ideally, Cu4(As,Sb)2S5, with As > Sb. The X-ray powder pattern resembles that of tetrahedrite but has subsidiary diffractions and is similar to that of synthetic Cu24As12S31 (Maske and Skinner, 1971). It is indexed on an orthorhombic cell with a = 14.51 Å, b = 13.30 Å, c = 17.96 Å (all ± 0.01 Å), and Z = 16. Calculated density is 4.66 g/ cm3. It is optically similar to tetrahedrite but is grey and weakly bireflectant. No internal reflections were observed. The maximum and minimum reflectance values in air and in oil (nD = 1.515) for the COM wavelengths are: 470 nm −32.5, 31.5; 17.7, 17.0, 546 nm −32.0, 31.1; 17.0, 16.3,589 nm −31.1, 30.3; 16.1 m 15.5, 650 nm −30.0, 29.3; 15.0, 14.5%, respectively. Watanabeite forms masses composed of aggregates of minute grains up to 50 μm in diameter. Apart from some minute inclusions of emplectite, native bismuth and tennantite, it is almost monominerallic.

Olivine (ol) leucitite lavas from Northeast China contain hyalophanes with contrasting Ba-zoning patterns. The hyalophanes occur: (1) in a magmatic inclusion (DZ2n), consisting of barian-titanian phlogopite + hyalophane + leucite + sodalite, and (2) as a mantle surrounding a sanidine megacryst (DZ19). Hyalophanes contain 4.6-20.2 mol.% celsian (Cn). The DZ2n hyalophane is normally zoned with respect to Ba (decreasing Ba toward rim), whereas the hyalophane mantle of megacryst DZ19 is reversely zoned. DZ2n probably crystallised from an extensively evolved (>80 wt.% crystallisation) potassic melt derived from a primitive magma chemically similar to the host, at relatively low temperatures and pressures (e.g. T-720°C P∼2 kbar). Competition with barian-titanian phlogopite for Ba, and limited Ba supply from the residual melt are the main cause for the normal Ba zonation. Sanidine megacryst DZ19 originated as a high P-T product (e.g. T > 950°C P > 15 kbar) of an evolved leucite (lc) basanite/trachybasalt genetically related to ol-leucitites. Subsequently, it was incorporated into the host ol-leucititic magma at which point it was partially resorbed and then mantled by hyalophane. An increase in KBaaf/liq values with decreasing temperature and pressure and cocrystallisation of the hyalophane mantle with Ba-free phases may have caused the unusual reverse zonation.

X-ray absorption spectroscopy, scanning electron microscopy (SEM) and X-ray diffractometry (XRD) have been used to study the solid-phase speciation of Zn in urban road dust sediments (RDS) in Manchester, UK. X-ray absorption near-edge structure (XANES) analysis using linear combination modelling suggest that the soluble species Zn(NO3)2·6H2O and ZnCl2 represent 70—83%, and Zn-sorbed goethite 17—30%, of the Zn species present. The presence of goethite is not corroborated by extended X-ray absorption fine structure (EXAFS) modelled first shell scattering Zn—O distances of 2.01—2.03 Å, but this may be due to distortion of the Zn octahedra on the goethite surface, or the existence of Zn-sorbed species with other metal hydrous oxides, as inferred by the EXAFS-modelled second shell Fe and Al scatterers. Analysis by EXAFS also suggests that metallic Zn-Cu-Sn-Pb and Zn-silicate phases are present in the RDS, and this is corroborated by SEM and XRD. Other phases suggested by EXAFS include ZnO, franklinite, Zn-sorbed birnessite and zinc formate. Differences between the XANES and other results suggest that model compounds such as Zn-bearing phyllosilicates and metallic Zn phases may have been missing from the XANES fitting. Long-term low-level exposure to the RDS Zn phases identified may lead to an increased risk of cardiovascular or pulmonary diseases.

A multi-methodological study, based on electron microprobe analysis (in wavelength dispersive mode), single-crystal X-ray diffraction (XRD), transmission electron microscopy and single-crystal Fourier transform infrared spectroscopy was performed in order to describe the crystal chemistry of four leucite samples from different localities of the Roman Comagmatic Province (central Italy). All the crystals examined were found to be tetragonal (space group I41/a with a = 13.076–13.103 Å and c = 13.744–13.784 Å) and characterized by a complex twinning (merohedric twins: on the tetragonal planes (110) and (1̄10) with the two individuals having parallel crystallographic axes with a and b interchanged; pseudo-merohedric twins: on the tetragonal planes (101), (011), (1̄01), (01̄ 1), with the two individuals having parallel a (or b) axes and the remaining two axes not parallel). The chemical analyses show that all the samples contain minor Na and Fe. Infrared spectroscopy shows that all samples contain structurally bound water molecules, up to unexpectedly large amounts (~0.4 wt.%) for a nominally anhydrous mineral, suggesting that ‘analcime-like’ substitution (K to Na + H2O) occurs in the leucite samples investigated here. The detection limits of the ‘analcime-like’ substitution by singlecrystal XRD are also discussed.

A REE-bearing fluorosilicate from the Tommot REE-Nb deposit in Yakutia, Russia, described without a name in 1966, is characterized here as a new species, proshchenkoite-(Y), of the vicanite group of borosilicates. Wavelength-dispersive electron probe analyses gave the following empirical formula: Y3.70REE7.54Ca1.55Na1.16Mn0.77Th0.10Pb0.01)Σ14.83(Fe2+0.83Mn0.15Ti0.02)Σ1.00Ca1.00(P0.70Si0.26As0.04)Σ1.00Si0.26B3.20(O34.55F13.45)Σ48. Boron was analysed with a nuclear microprobe method based on the nuclear reaction 11B(p,α)2α. The simplified formula is (Y,REE,Ca,Mn)15(Fe2+,Mn)Ca(P,Si)Si6B3O34F14. The mineral is trigonal, R3m, with a = 10.7527(7) Å, c = 27.4002(18) Å, V = 2743.6(6) Å 3, Z = 3. The crystal structure was refined to Rl = 0.042 for 1819 observed reflections. Proshchenkoite-(Y) is isostructural with okanoganite-(Y), vicanite-(Ce) and hundholmenite-(Y), and the differences in site occupancies are discussed. The strongest six reflections of the X-ray powder-diffraction pattern [dobs in Å, (I), (hkl)] are: 4.441, (36), (202); 3.144, (77), (214); 3.028, (45). (009); 2.968, (100), (027); 1.782, (32), (330); and 1.713, (32), (1.2.14). The mineral is optically uniaxial (—) with ω 1.734(2) and 8 1.728(2). The Mohs hardness is about 5; density measured on material subject to incipient metamictization is 4.72 g/cm3, as compared to Dcalc = 4.955 g/cm3.

The result of electron microprobe analyses of alleged okanoganite-(Y) from the type locality in Okanogan County, Washington, USA, is also presented. We find here also that P > Si at one of the sites, whereas the analytical data of Boiocchi et al. (2004) indicate Si > P. Consequently, the mineral we have analysed is the P analogue of okanoganite-(Y), another new species.

X-ray diffraction refinement of the crystal structure of eosphorite has been carried out with reference to the orthorhombic space group Cmca. The structure is similar to that previously described by Hanson (1960), but the standard deviations are improved. Optical absorption and photoluminescence have also been studied for this mineral. Two sharp emission lines, denoted as R1 and R2, superimposed to a broad band (630-750 nm) have been related to the presence of Cr3+ ions. The excitation spectrum of these emissions confirms that the absorption (excitation) bands centred at 431 nm and 585 are related to with 4A2 → 4T1 and 4A2 → 4T2 spin allowed transitions of this ion.

Garnets, omphacite and the minerals of a clinopyroxene/amphibole/plagioclase symplectite in UHP eclogites from Yingshan, Dabieshan have been investigated by TEM and Micro-FTIR. TEM reveals that the predominant microstructures in eclogites and symplectite-forming minerals are chain multiplicity faults (CMFs), dislocation substructures, clusters of water molecules up to ∼50 nm in diameter and recrystallized grains ∼1.75 μm in diameter. This indicates dynamic recrystallization of omphacite, probably during an eclogite-facies metamorphic episode. The deformation structures in symplectite-forming minerals were produced by plastic deformation related to an amphibolite-facies retrograde metamorphic event. CMFs described in the present work demonstrate the existence of an infrequent ½<011> (010) slip system for P2/n omphacite from an UHP eclogite sample from Dabieshan. The frequent occurrence of CMFs in omphacite suggests that they indicate an important deformation mechanism in omphacite and shows that this slip system plays a significant role in the deformation and recovery of eclogite. The hydrous components of deformed minerals may cause plastic deformation of the rocks by dislocation movement and accelerate retrograde metamorphism. Micro-FTIR results show that all the garnets and omphacites contain structural water occurring as hydroxyl groups (OH) or water (H2O). The structural water contents in omphacite range from 110—710 ppm and in garnet from 0—180 ppm. Water released during decompression might supply an early-stage retrograde metamorphic fluid.

Unit-cell dimensions and refractive indices of lithium-iron micas decrease with decreasing iron and increasing lithium. Indices β and γ as well as parameters a and b can be used to estimate the composition of lithium-iron micas but basal spacing and 2Vα are poor indicators of composition.

The chemical composition of natural lithium-iron micas from the Krušné hory and the Erzgebirge along the Czechoslovak—German border was discussed in Part A of this study (Rieder et al., 1970). It was concluded that the composition and crystallography of these micas fit best the series siderophyllite-polylithionite. The compositions were expressed by the ratio A′ = LR/(LR+‘Fe’). In this expression, LR is the subscript value of Li or octahedral R3+ (whichever is the smaller) in the crystallochemical formula, ‘Fe’ is the sum of the values in the formula of Fe2+ and Mn2+. A′ therefore defines the position of a particular mica on the siderophyllite-polylithionite join. This paper deals with the correlation between composition, cell dimensions, and refractive indices.

Sulphide and sulphosalt mineralization in the Hällefors silver mining district occurs as stratabound bodies in skarn-like black carbonates and other carbonates in the eastern part of the district, and as epigenetic, tectonically controlled vein mineralization in tuffaceous metavolcanics and, to a lesser extent in slates, in the western part.

Previous work has suggested that the Ag-bearing Hällefors deposits were formed by the action of metamorphic solutions on sediments of volcano-sedimentary origin. At the stages of sulphosalt and sulphide formation, temperature and pressure conditions were probably in the ranges 500–440 K and 4.5–3.5 kbar. Examination of a log aS2-1/T diagram and of Ag-Sb phase relations combined with study of the ores suggest the paragenesis of the Ag-bearing minerals is as follows: allargentum and dyscrasite as exsolution bodies in silver bearing galena; Ag-containing tetrahedrite → freibergite → miargyrite → pyrargyrite → stephanite (from hydrothermal solutions).

Ludwigite from B-bearing iron ores in the Bergslagen area of central Sweden and in the coastal area north of Stockholm has been studied using chemical and single-crystal diffraction techniques. Structure refinements, completed for three crystals showing slightly different Al contents, in the space group Pbam (agreement factor: 2.42 ≤ R ≤ 2.79) indicate that: (1) octahedral M1, M2 and M3 bond distances are similar, although the calculated site population suggests that M1 and M2 are nearly completely occupied by Mg whereas M3 also contains Fe2+ and Fe3+; (2) in the M4 octahedron Fe3+ and Al dominate over Mg (and Fe2+); and (3) the distortion parameter, BLD, indicates that M3 is the most regular, whereas M4 is the most distorted octahedron.

From the microscopic examination of lightly etched, cleaved (111) surfaces of banded blue fluorite (Blue John, from Castleton, Derbyshire) it is concluded that the coloured lamellae are not necessarily or exclusively associated with lattice-line imperfections. Elemental analyses, by electron dispersive methods, of fresh cleavage (111) surfaces in the immediate vicinity of small inclusions (c. 10 µm diameter) possessing associated coloured haloes detected no appreciable concentrations of impurities. From the evidence available, it is suggested that the zones of blue colour consist of colloidal calcium resulting from radiation damage caused by the intermittent deposition of radioactive material on the surfaces of fluorite during crystal development. The dispersion of colloidal calcium produced is particularly stable as a consequence of the close correspondence between lattice spacings in calcium fluoride and in calcium metal.

Abundant kiddcreekite grains were identified in the Zijinshan Cu-Au epithermal deposit in Fujian Province, China. The mineral occurs as polycrystalline grains, 5–300 μm in size, associated with colusite, enargite, stannoidite, mawsonite, vinciennite, hemusite, tennantite and wolframite in a predominantly covellite ore. Based on electron microprobe analysis, the empirical formula of the kiddcreekite is Cu6.2Sn0.97W0.95S7.83, without significant Se or Te contents. The crystal structure of kiddcreekite was solved using the direct-space method (EPCryst) from laboratory micro X-ray diffraction (μXRD) data and refined by the Rietveld method. The R values of the final Rietveld refinement were Rp = 9.06%, Rwp = 8.31%, RB = 3.16 and RF = 2.17%. Kiddcreekite has a cubic structure, space group F3m and lattice parameter a = 10.8178(3) Å (Z = 4, V = 1265.95(6) Å3). In the unit cell, W, Sn and Cu atoms occupy the 4a, 4c and 24f Wyckoff positions, respectively, and S atoms occupy two sets of 16e Wyckoff positions. The structure of kiddcreekite consists of stacked double MeS4 layers (giving a W–Sn–Cu tier and a Cu–vacancy tier) as in the sphalerite substructure. This study also demonstrates the possibility of using laboratory µXRD data coupled with the direct-space method to solve inorganic structures in cases where samples are too small for conventional powder and single-crystal diffraction.

The recently described electrolysis of molten basalt (Oppenheim, 1968) gave indefinite results with regard to the behaviour of iron. Repeating the experiments in an inert atmosphere has shown that ferric iron moves towards the anode, and ferrous iron to the cathode. All metallic ions of valency three and more are now seen to be concentrated towards the anode, with relative enrichments in decreasing order: Fe3+, P, Ti, Si, and Al; and oxygen gas is released at the anode. Metals of valency one and two are concentrated towards the cathode with relative enrichments in decreasing order: Na, Fe2+, K, Ca, Mn, and Mg.

The series expected to be differentiated within a magma consequent upon its electrolysis is redefined. The absence of natural analogues suggests either the non-operation of suitable electric currents within magmas, or the destruction of their effects by convection, fractional crystallization, or both. An electrolytic process is feasible at the mantle-core boundary, leading mainly to deposition of iron on the core and release of oxygen upwards.