Cobaltite-rich mineralization from the iron skarns of the Traversella magnetite mine (Western Alps, Italy) was studied by reflected-light microscopy, scanning electron microscopy and electron microprobe analysis. Cobaltite is found in carbonate-chlorite-rich rocks at the margins of the main magnetite masses, where it forms disseminations and metasomatic veinlets that postdate the formation of magnetite. The paragenesis includes cobaltite (± arsenopyrite), bismuthinite, pyrrhotite and/or pyrite, chalcopyrite, carbonates, talc, chlorite and native gold, and is indicative of a low-sulfidation environment. The sulfarsenides show oscillatory and sector zoning, which indicates disequilibrium during crystal growth. Compositional variations are mainly due to variations in the Co/Fe ratio of arsenopyrite and in either the Co/Fe or the Ni/(Fe + Co) ratios of the coexisting cobaltite. The Ni contents are low to very low in the cobaltites (<2.4 wt.%) and very low in the arsenopyrites (<0.16 wt.%). The As/S molar ratios in the cobaltites are highly variable (0.59−1.00) and show a broad negative correlation with the Fe contents. The formation of cobaltite is related to circulation of relatively low-temperature (<∼300°C), (Co,As,Bi)-rich fluids during the retrograde sulfidation stage which followed the formation of magnetite. The apparent restriction of cobaltite (+ bismuthinite ± arsenopyrite) to the margins of the main magnetite columns may reflect the establishment of thermochemical gradients around the main direction of infiltration of the retrograde metasomatic fluids.

The phase transitions involving calcite (CaCO3-I), CaCO3-II, CaCO3-III and CaCO3-IIIb were investigated using a diamond anvil cell and micro-Raman spectroscopy. Based on the results obtained from in situ observations and Raman measurements made with six natural calcite crystals, the phase transition from calcite to CaCO3-II took place between 1.56 and 1.67 GPa under ambient temperature. Under a precise pressure of 1.97 ± 0.03 GPa, three CaCO3 samples were observed to transform from CaCO3-II directly to CaCO3-III, while in the other three samples both CaCO3-III and CaCO3-IIIb crystal structures were detected. Transformation from CaCO3-IIIb to CaCO3-III was completed in a short period in one sample, whereas in the other two samples coexistence of CaCO3-III and CaCO3-IIIb was observed over a wide pressure range from 1.97 to 3.38 GPa, with sluggish transformation from CaCO3-IIIb to CaCO3-III being observed after the samples were preserved under 3.38 GPa for 72 h. Hence, it can be concluded that CaCO3-IIIb is a metastable intermediate phase occurring during the reconstructive transformation from CaCO3-II to CaCO3-III. Splitting of the C–O in-plane bending (ν4) and symmetric stretching (ν1) vibrations and appearance of new lattice vibrations in the Raman spectra of CaCO3-III and CaCO3-IIIb suggest a lowering in crystal symmetry during the transformation from CaCO3-II through CaCO3-IIIb to CaCO3-III, which is in good agreement with the observed sequence of phase symmetries.

The quantitative distribution of igneous rocks has recently assumed a place of importance in petrogenic discussions. This is due largely to the influence of Daly, who made a survey of the areal distribution of rock types as shown by their outcrops on published maps, and reached the well-known conclusion that intrusions are overwhelmingly granitic in composition, and that extrusions arc largely basaltic. If further research should firmly establish this result, it will unquestionably be a fact of the first order of importance of which any general theory of petrogenesis must take cognizance.

The mechanisms by which coatings develop on weathered grain surfaces, and their potential impact on rates of fluid-mineral interaction, have been investigated by examining feldspars from a 1.1 ky old soil in the Glen Feshie chronosequence, Scottish highlands. Using the focused ion beam technique, electron-transparent foils for characterization by transmission electron microscopy were cut from selected parts of grain surfaces. Some parts were bare whereas others had accumulations, a few micrometres thick, of weathering products, often mixed with mineral and microbial debris. Feldspar exposed at bare grain surfaces is crystalline throughout and so there is no evidence for the presence of the amorphous ‘leached layers’ that typically form in acid-dissolution experiments and have been described from some natural weathering contexts. The weathering products comprise sub-urn thick crystallites of an Fe-K aluminosilicate, probably smectite, that have grown within an amorphous and probably organic-rich matrix. There is also evidence for crystallization of clays having been mediated by fungal hyphae. Coatings formed within Glen Feshie soils after ∼1.1 ky are insufficiently continuous or impermeable to slow rates of fluid-feldspar reactions, but provide valuable insights into the complex weathering microenvironments on debris and microbe-covered mineral surfaces.

The present work deals with the synthesis of kalsilite using material from a kaolinitic rock outcrop in Romana, Sassary Province, Sardinia, Italy.

The hydrothermal synthesis method required the dissolution of kaolin and Al(OH)3 in a KOH solution at a temperature of 190°C and 1.013 bar. Crystallization of kalsilite was confirmed at 12 h in association with kaliophilite H2 as a metastable phase.

The products of synthesis were fully characterized by powder X-ray diffraction, scanning electron microscopy, inductively coupled plasma optical emission spectrometry, infrared spectroscopy and 29Si nuclear magnetic resonance. The amorphous phase in the synthesis powders was estimated with quantitative phase analysis using the combined Rietveld and reference intensity ratio methods. Cell parameters and density were also calculated for the kalsilite. A potential application of kalsilite was investigated as a heterogeneous catalyst for biodiesel synthesis from sunflower oil used for frying.

Lattice parameters of synthetic titanite powder, CaTiOSiO4, have been determined between room temperature and 1023 K. Only the e11 and e13 components contribute significantly to the strain tensor associated with the antiferroelectric-paraelectric phase transition at Tc = 487 K. A finite strain component e13 is observed in the paraelectric phase for 487 K < T < 825 K. The disappearance of this shear strain marks the isosymmetric transition near 825 K. The temperature evolution of the volume strain and of e11 is proportional to the squared order parameter observed in single-crystal diffraction experiments. The magnitude of the volume strain is sufficiently large to relate the observed near tricritical behaviour of the antiferroelectric-paraelectric phase transition to strain coupling.

The crystal structure of bornemanite, ideally Na6☐BaTi2Nb(Si2O7)2(PO4)O2(OH)F, a = 5.4587(3), b = 7.1421(5), c = 24.528(2) Å, α = 96.790(1), β = 96.927(1), γ = 90.326(1)°, V = 942.4(2) Å3, space group (P1̄), Z = 2, Dcalc. = 3.342 g cm–3, from the Lovozero alkaline massif, Kola Peninsula, Russia, has been solved and refined to R1 = 6.36% on the basis of 4414 unique reflections (Fo >4sF). Electron microprobe analysis yielded the empirical formula (Na6.07Mn2+0.23Ca0.06☐0.64)Σ7.00 (Ba0.73K0.13Sr0.06☐0.08)Σ1.00(Ti2.05Nb0.80Zr0.02Ta5+0.01Fe3+0.03Al0.02Mn2+0.06Mg0.01)Σ3.00(Si2O7)2(P0.97O4)O2 [F1.27(OH)0.74]Σ2.01. The crystal structure of bornemanite is a combination of a TS (titanium silicate) block and an I (intermediate) block. The TS block consists of HOH sheets (H-heteropolyhedral, O-octahedral). The TS block exhibits linkage and stereochemistry typical for Group III (Ti = 3 a.p.f.u.) of Ti-disilicate minerals: two H sheets connect to the O sheet such that two (Si2O7) groups link to the trans edges of a Ti octahedron of the O sheet. The O sheet cations give Na3Ti (4 a.p.f.u.). The TS block has two different H sheets, H1 and H2, where (Si2O7) groups link to [5]Ti and [6]Nb polyhedra, and there are two peripheral sites which are occupied by Ba and Na, respectively. There are two I blocks: the I1 block is a layer of Ba atoms; the I2 block consists of Na polyhedra and (PO4) tetrahedra.

The crystal structure of the rare lead hydroxychloride paralaurionite [PbCI(OH), monoclinic, space group C2/m, a = 10.865(4), b = 4.006(2), c = 7.233(3) Å, β = 117.24(4)°] has been refined to R = 0.062, Rw = 0.048. Its Order-Disorder (OD) character and its OD relationships with the orthorhombic polytpe of PbCI(OH), laurionite, are discussed. Laurionite and paralaurionite represent the two MDO structures within a family of OD structures built up by two different kinds of layers. The structures of paralaurionite and laurionite are compared thoroughly. The first coordination of the various atoms in the two polytypes is the same, however, remarkable differences exist in the connection between adjacent Pb-centred polyhedra.

Electron microprobe analyses of prehnites from the Way Linggo low-sulphidation epithermal Au-Ag deposit of southern Sumatra, show that the mole fraction of octahedral Fe3+, expressed as Fe3+/(Fe3++AlVI), ranges from 0.0 to ~0.6, the higher values being among the most iron-rich reported for prehnite in a hydrothermal environment. Prehnites from a diabase sill in the Heber geothermal field of California have mole fractions of octahedral Fe3+ ranging from 0.03 to 0.3. The Way Linggo prehnites formed below 220°C, some 20–30°C lower than those at the Heber field; the lower crystallization temperatures perhaps enhanced the opportunity for Fe3+ to substitute in octahedral sites. In both occurrences, prehnite predates late-stage calcite, consistent with the need for waters depositing prehnite to have aCO2 <0.01 moles. At higher CO2 activities the stability field of calcite would swamp the range of aCa2+/aH+ values appropriate for crystallizing prehnite. Consequently, the presence of prehnite in a hydrothermal environment primarily indicates that degassing of the hydrothermal fluid in CO2 occurred prior to deposition.

Quantitative measurement of relative flexibility have been made on amphibole fibres based on calculation of bending strain of maximally bent fibre segments. Enhanced flexibility was found to be an inverse function of fibre diameter. Asbestos is therefore a morphological entity. These conclusions are supported by consistent observations of fibre diameter/flexibility relationships in amphiboles, serpentine, and rutile. Flexibility may arise from growth of thin crystals (primary flexibility), or from crystal diameter reduction (secondary flexibility). Mechanisms for secondary flexibility in amphiboles include splitting and solution along cleavage planes. Gross morphological characteristics are a poor indicator of microscopic habit, since coarsely fibrous minerals such as picrolite antigorite may not be fibrous after particle width reduction, and secondary asbestiform fibres are often derived from minerals with a non-fibrous morphology on gross examination.

Two novel copper selenite chlorides, K[Cu3O](SeO3)2Cl (I) and Na2[Cu7O2](SeO3)4Cl4 (II), have been synthesized by the CVT method. Their crystal structures have been solved by direct methods and refined by least-squares techniques. I is triclinic, space group P1̄, a = 7.6821(5), b = 8.1179(5), c = 8.7836(6) Å, α = 113.193(3), β = 108.735(4), γ = 98.245(4)°, V = 453.32(5) Å3, R1 = 0.0481 for 1210 unique reflections with F≥4σ(F); II is triclinic, space group P1̄,a = 7.4362(6), b = 8.3361(7), c = 9.1343(11) Å,α = 110.277(6), β = 106.212(6), γ = 105.158(4)°, V = 467.94(8) Å3, R1 = 0.0265 for 2498 unique reflections with F≥4σ(F). The structures of I and II can be described in terms of dimers of copper oxocentred tetrahedra. In I, two (OCu4)6+ tetrahedra share a common Cu···Cu edge to form the [O2Cu6]8+ dimer, whereas the structure of II is based upon two (OCu4)6+ tetrahedra linked together by one common Cu atom resulting in the formation of the [O2Cu7]10+ dimer. A comparison with related minerals and inorganic compounds is given.

A new compositional variety of zirconolite characterized by high Mg, Al, Y2O3 and REE, and low Fe is described from a sapphirine granulite xenolith entrained in an intrusive norite body which was emplaced into the late Archaean (2520–2480 Ma) Vestfold Hills high-grade terrain during the early Proterozoic. The zirconolite, and similarly Mg-Al rich perrierite-(Ce), formed as a result of sanidinite facies partial melting of the particularly magnesian and aluminous sapphirine granulite xenolith during its incorporation into the c. 1170°C basic magma at c. 2240 Ma. The high REE compared to Al cations require that a previously unrecognized coupled substitution:

occurs in this zirconolite. Full chemical analyses are presented for zirconolite and perrierite from this unique occurrence.

Characterization of Brazilian agates containing a lower horizontally banded section and an upper chamber with bands parallel to the walls shows that these agates formed much later than the 135 Ma Paraná basalt host rock. Age differentiation between the two types of banding shows that the horizontal bands formed between 43 to 63 Ma ago with a final infill of wall-lining bands between 7 and 27 Ma later. The horizontal bands have a higher Al3+ concentration and a greater crystallite size than the wall-lining layers; they have a lower mogánite content and defect-site water content. The formation of these agates appears to be the result of a three-stage process. After the separate formation of horizontally banded and wall-lining agate, a silica infill seals the gap between the agate and the cavity wall. The detection of cristobalite in some specimens indicates that genesis of both the horizontally banded and wall-lining deposits in the Brazilian samples proceeds along an amorphous silica → opal-CT → opal-C → chalcedony pathway.

Two new isostructural minerals edtollite K2NaCu5Fe3+O2(AsO4)4 and alumoedtollite K2NaCu5AlO2(AsO4)4 have been found in the Arsenatnaya fumarole, Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. They are associated with sylvite, tenorite, dmisokolovite, shchurovskyite, johillerite, bradaczekite, and orthoclase. Edtollite forms prismatic crystals up to 0.02 mm × 0.1 mm; alumoedtollite forms long-prismatic crystals up to 0.01 mm × 0.1 mm. Both minerals have a semi-metallic lustre. Edtollite is brown–black to black and alumoedtollite is bronze coloured. Dcalc. = 4.26 (edtollite) and 4.28 (alumoedtollite) g cm–3. In reflected light, both minerals are grey, with distinct anisotropy. Reflectance values [edtollite/alumoedtollite: R1–R2, % (λ, nm)] are: 8.3–8.2/8.7–7.7 (470); 7.7–7.4/8.3–7.4 (546); 7.1–6.9/8.3–7.4 (589); and 6.3–6.3/7.6–7.2 (650). Chemical data are: (edtollite/alumoedtollite, wt.%, electron-microprobe): Na2O 3.13/2.58, K2O 8.12/9.09, Rb2O 0.00/0.11, CaO 0.00/0.52, CuO 36.55/38.35, ZnO 0.46/0.00, Al2O3 0.00/3.48, Fe2O3 7.34/1.79, TiO2 0.27/0.00, As2O5 43.57/43.66, total 99.44/99.58. The empirical formulae, based on 18 O apfu, for edtollite is: K1.83Na1.07Cu4.88Zn0.06Fe3+0.98Ti0.04As4.03O18; and for alumoedtollite is: K2.02Rb0.01Na0.87Ca0.10Cu5.06Al0.72Fe3+0.24As3.99O18. Both minerals are triclinic, P$\bar{1}$; unit-cell parameters (edtollite/alumoedtollite) are: a = 5.1168(6)/5.0904(11), b = 9.1241(12)/9.0778(14), c = 9.6979(14)/9.6658(2) Å, α = 110.117(13)/110.334(17), β = 102.454(12)/102.461(19), γ = 92.852(11)/92.788(15)°, V = 411.32(9)/404.88(14) Å3 and Z = 1/1. The strongest reflections in the powder X-ray diffraction pattern [d,Å(I)(hkl)] are for edtollite: 8.79(92)(001), 7.63(41)(0$\bar{1}$1), 5.22(44)(011), 3.427(100)(012), 3.148(64)(0$\bar{1}$3), 2.851(65)($\bar{1}$03) and 2.551(40)($\bar{2}$01); and for alumoedtollite: 8.78(81)(001), 7.62(67)(0$\bar{1}$1), 3.418(100)(012), 3.147(52)(0$\bar{1}$3), 2.558(58)($\bar{1}$22), 2.544(65)($\bar{2}$01) and 2.528(52)($\bar{1}\bar{3}$2). The crystal structures [single-crystal X-ray diffraction, R = 0.0773 (edtollite) and 0.0826 (alumoedtollite); 1504 and 1046 unique reflections, respectively] represent a novel structure type. It is based upon a heteropolyhedral pseudo-framework with the column formed by Cu2+-centred octahedra and square pyramids, octahedra MO6 (M = Fe3+, Al3+ or Cu2+) and AsO4 tetrahedra as the main building unit. K+ and Na+ are located in wide and narrow channels, respectively. Edtollite is named after the Russian geologist and Arctic explorer Eduard Vasilievich Toll (1858–1902), alumoedtollite is its analogue with Al prevailing among trivalent cations.

Geological repository designs employ a multi-barrier approach. The materials, which include wasteforms, backfill and host rock, are typically porous quasi-brittle. Mechanical damage (e.g. nucleation and growth of microcracks) can result in significant changes in permeability. A knowledge of how the permeability is affected is critical to accurate modelling of radionuclide transport. This work proposes a novel 3D lattice-type model for the damage evolution in such materials, referred to as the site-bond model. Its advantages over previous models are that the shape of the lattice cell is physically realistic and that any macroscopic elastic response can be represented, including those of cementitious and geological materials. Damage accumulates as bonds fail upon reaching prescribed failure strengths. These are dictated by a predefined pore size distribution. Concrete is used as a study material. It is demonstrated that the model can predict the macroscopic stress–strain response under unconfined tension and compression with emergent non-linearity due to damage evolution. Ongoing work on the prediction of permeability changes with damage is discussed. This is based on the interaction between the model proposed here and a lattice model of the pore space.

Evdokimovite, ideally Tl4(VO)3(SO4)5(H2O)5, was found in a fumarole of the 1st cinder cone of the North Breach of the Great Fissure Tolbachik volcano eruption of 1975–1976, Kamchatka Peninsula, Russia. Evdokimovite occurs as thin, colourless needles up to 0.09 mm long associated with shcherbinaite, pauflerite, bobjonesite, markhininite, karpovite and microcrystalline Mg, Al, Fe and Na sulfates. Evdokimovite is monoclinic, P21/n, a = 6.2958(14), b = 10.110(2), c = 39.426(11) Å , β = 90.347(6)º, V = 2509.4(10) Å3 and Z = 4 (from single-crystal diffraction data). The eight strongest lines of the powder X-ray diffraction pattern are (I/d/hkl): 57/9.793/011, 100/8.014/013, 26/6.580/006, 19/ 4.011/026, 29/3.621/118, 44/3.522/125, 19/3.010/036, 21/2.974/212. Chemical composition determined by the electron microprobe analysis is (wt.%): Tl2O 55.40, VO2 14.92, SO3 25.83, H2O 5.75, total 101.90. The empirical formula for evdokimovite calculated on the basis of (Tl + V + S) = 12 a.p.f.u. is Tl4.10V2.83S5.07H10.00O27.94. The simplified formula is Tl4(VO)3(SO4)5(H2O)5. The crystal structure was solved by direct methods and refined to R1 = 0.11 on the basis of 3660 independent observed reflections. V4+O6 octahedra and SO4 tetrahedra share common corners to form two types of vanadyl-sulfate chains, [(VO)(H2O)2(SO4)2]2– and [(VO)2(H2O)3(SO4)3]2–. Thallium atoms are located in between the chains. The structure can be described as a stacking of layers of two types, A and B. The A layer contains [(VO)2(H2O)3(SO4)3]2– chains and the Tl2 and Tl3 atoms, whereas the B layer contains [(VO)(H2O)2(SO4)2]2– chains and the Tl1 atoms. Stacking of the layers can be described as ...A’*BAA’B*A*..., where A and A’ denote A layers with opposite orientations of the [(VO)2(H2O)3(SO4)3]2– chains, and the A* and B* layers are rotated by 180º relative to the A and B layers, respectively. [(VO)2(H2O)3(SO4)3]2– chains are modulated and are arranged to form elliptical tunnels hosting disordered Tl(4), Tl(4A) and Tl(4B) sites. The new mineral is named in honour of Professor Mikhail Dmitrievich Evdokimov (1940–2010), formerly of the Department of Mineralogy, St Petersburg State University, for his contributions to mineralogy and petrology, and especially for teaching mineralogy to several generations of students at the University. Evdokimovite is the most complex V4+ sulfate known to date with structural information amounting to 1130 bits per unit cell, which places evdokimovite among minerals with the complexity of the vesuvianite group.

A new method for measuring the crystallinity index of quartz is presented. It is based on the measurement of the intensity of the first derivative of the infrared absorption spectrum at the shoulder at c. 1145 cm−1. The results correlate well with X-ray and D.T.A. crystallinity measurements.