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Several artefacts occurring during TEM sample preparation by ion-milling and observation, which cannot be straightforwardly discerned from genuine properties of the sample, are presented and discussed, with the aim to warn unexperienced microscopists against misinterpretation of TEM data. The cases presented here span from typical material sputtering and redeposition during ion-milling sample preparation, or sample decomposition under the electron beam, to more exotic cases of sample recrystallization during observation or during storage within the grid box. Overall, 15 different case studies, categorized among artefacts produced during (i) preparation, (ii) observation, (iii) microanalysis and (iv) sample storage are illustrated and discussed. The paper ends with recommendations on how minimize both preparation- and observation-induced artefacts, with specific mention to minerals.

Šlikite, Zn2Mg(CO3)2(OH)2·4H2O is a new supergene post-mining mineral from the Jáchymov (formerly St. Joachimsthal) ore district, Czech Republic, associated with brianyoungite, hexahydrite, hydromagnesite, nesquehonite, serpierite, smithsonite and a ktenasite-like mineral. It forms snow-white radial aggregates, up to 2 mm across, in vugs or on surfaces of fragments of skarn rocks. Individual crystals are very thin blades, elongated along [110] and flattened on {001}, up to 200 µm in length. Šlikite has a white streak, a vitreous lustre, and does not fluoresce under either short- or long-wave ultraviolet light. Cleavage is perfect on {001}, the Mohs hardness is ~2, and the fracture is uneven. The mineral is brittle, although thin blades (fibres) are slightly flexible. The calculated density is 2.613 g/cm3. Šlikite is optically biaxial negative, the indices of refraction are a = 1.50(1), ß = 1.55(1), ? = 1.59(1) and 2V meas. = 80(1)°. The mineral is triclinic, space group P 1 ¯ , a = 6.335(4), b = 6.340(1), c = 13.923(4) Å, a = 99.985(7)°, ß = 92.74(1)°, ? = 114.93(2)°, V = 494.8(4) Å3, Z = 2. The six strongest lines in the X-ray powder diffraction pattern are [d (Å)/I(hkl)]: 13.575/100(001), 4.525/31(003), 3.573/2(1 1 ¯ 3), 3.406/5(11 1 ¯ ), 2.996/3(11 3 ¯ ) and 2.773/3(112). The chemical analyses by electron microprobe yielded MgO 8.39, ZnO 46.28, CuO 0.05, MnO 0.68, CdO 0.04, CO2calc. 23.10, H2Ocalc. 23.65, total 102.19 wt%. The empirical formula on the basis of 12 O atoms per formula unit is Zn2.00(Mg0.79Zn0.17Mn0.04)S1.00(CO3)2(OH)2·4H2O. The crystal structure of šlikite was refined using synchrotron single-crystal data to R obs = 0.094 for 1594 reflections with I > 3s(I). The structure of šlikite is based on heteropolyhedral layers of composition [Zn4Mg(CO3)4(OH)4]2-, parallel to {001}, with interlayer H-bonded [Mg(H2O)6]2+ and H2O. Within the layers, [110] chains of corner-connected ZnO2(OH)2 tetrahedra share corners with Mg-centred octahedra. The two types of polyhedra are connected via CO3 groups. The Raman and infrared spectra of šlikite as well as tentative assignment of observed bands are given in this paper. The mineral is named in honour of the prominent Czech aristocrat Štepán Šlik (1487–1526), founder of town St. Joachimsthal (now Jáchymov).

Throughout history, human civilizations have combined clay soils with additives to produce better brick building material. Recently, bricks have been used as a method of eliminating industrial and agricultural wastes by incorporating the waste into brick raw mixtures. In this paper, the effects of three additives on the clay mixture and the fired bricks have been studied. Clayey soil from Jun (Granada, Spain) was combined with fly-ash, household glass and spent beer grain in manually made bricks fired at 800 °C, 950 °C and 1100 °C. Differences in mineral composition, porosity, water behavior, mechanical resistance and color were analyzed through chemical, mineralogical, textural and physical analyses. The presence of carbonates in the clayey soil favored the formation of Ca (–Mg) silicates such as gehlenite, diopside and anorthite in the fired bricks. Only bricks with fly ash displayed growth of secondary acicular calcite crystals. Overall, the additives altered brick porosity and compactness. Bricks made with added glass were found to be the most compact and resistant bricks while those made with spent beer grain were the most porous and fragile. These results have important implications for the construction industry and for the conservation of architectural heritage.

Single-crystal X-ray crystal-structure refinements and electron-microprobe analyses of two julgoldite samples, in one case complemented by Mössbauer spectroscopy to determine the Fe valence distribution, yielded the compositions Ca2.00X(Fe2+0.44Fe3+0.29Mg0.17Al0.10)Y(Fe3+0.82Al0.18)2Si3O10.39(OH)3.61 (Bombay) and Ca2.00X(Fe0.67Mg0.16Al0.17)Y(Fe3+0.81Al0.19)2Si3O14?-?n(OH)n (4?=?n?=?3) (Kreimbach/Kaulbach), respectively. Structure refinements also allowed specification of the system of hydrogen bonds, which concur with those known for pumpellyite. A review of structural and chemical data for pumpellyite-group minerals including six julgoldite samples indicated that the length of the b axis is governed by the average size of ionic radii at the Y site, except for one sample of julgoldite-(Fe3+). Size effects of the concentration of “large” divalent cations (Mg, Fe) at the X site can be seen in the lateral extension of the (010) plane that acts as a buffer to accomodate the variable size of the X octahedra. Using unit-cell plots, the data suggest that five of the six tested julgoldite samples are julgoldite-(Fe2+) and only the one sample of the Bombay area studied by Artioli et al. (2003) is julgoldite-(Fe3+). Both samples studied in this paper were classified into julgoldite-(Fe2+). In contrast to pumpellyite samples sensu stricto, which exhibit a Me2+:Me3+ ratio of approximately 1:1, julgoldite samples may cover the whole range between Ca2X(Fe3+)Y(Fe3+)2Si3O11(OH)3 and Ca2X(Fe2+)Y(Fe3+)2Si3O10(OH)4.

Clino-oscarkempffite, Ag1.27Pb0.49Sb1.68Bi1.54S6.01, idealized as Ag1.25Pb0.5Sb1.75Bi1.5S6 (Z?=?12), from the Colorada vein, Animas mine, Chocaya Province, Department of Potosi, Sur Chichas, Bolivia, is an N?=?4 member of the lillianite homologous series, oversubstituted according to the Ag?+?(Bi, Sb)???2Pb substitution to 122.8% in comparison to the formula of gustavite, AgPbBi3S6. Optical properties of clino-oscarkempffite are very similar to those of oscarkempffite and other Bi (Bi–Sb) lillianite homologues. Reflectance values in air vary between 47.5 and 35.2%. Hardness was evaluated to 3–3½, based on VHN50 range 189–208, mean 200?kg?mm-2. Density was calculated to 6.04?g?cm-3. Minerals associated with clino-oscarkempffite are aramayoite, oscarkempffite, arsenopyrite, ferrokësterite, freibergite, miargyrite, pyrite and quartz. Clino-oscarkempffite is monoclinic, lattice parameters a 39.811(25)?Å, b 19.280(12)?Å, c 8.278(5)?Å, ß 96.195(9)°, V 6316.7?Å3, space group P21/c. It is a three-fold superstructure of the lillianite aristotype, with a doubled 4?Å axis and, uniquely, a tripled ~13.3?Å a parameter. In the crystal structure, configured as a general N?=?4 lillianite homologue, the central octahedra of the PbS-like slabs are mixed (Bi,Sb), (Sb,Bi) and Sb sites in alternation along the 8.3?Å direction, whereas in the marginal coordination octahedra (Sb,Bi) positions alternate with distorted tetrahedral coordinations of Ag. The bicapped trigonal coordination prisms on meeting planes of two octahedral slabs are occupied by mixed (Pb,Bi) sites. Cation occupation schemes result in blocks with monoclinic overall symmetry which alternate along [1?0?0] with blocks with orthorhombic overall symmetry. The order–disorder implications of this division are discussed in the paper.

The interest for the environmental, industrial and technological applications of Si-rich zeolites is very high. Among the large-pore zeolites, faujasite is one of the most exploited. The aim of this paper is to obtain detailed structural information on natural and NH4-exchanged faujasite before using this zeolite for dealumination tests, targeting the realization of large single crystals of all-silica faujasite. As one of the most Si-rich natural samples, faujasite from Sasbach (Na13.64K0.87Mg10.46Ca8.89Sr0.34(Al51.95Si139.57)O384·272.29 H2O; space group Fd-3m;a?=?24.6906(2)?Å) was chosen for study. Single-crystal X-ray diffraction structural refinements of both natural and NH4-exchanged samples are reported and discussed. In the natural faujasite sample, almost all the extraframework species could be located for the first time. In the NH4-exchanged sample the ammonium and water molecule sites were located. Ammonium cations occupy two of the sites occupied by the extraframework species in the original mineral.

This paper is a review devoted to a special type of arsenic mineralization related to volcanic fumaroles of the oxidizing type. Fifty-four hydrogen-free arsenates (40 valid species and 14 insufficiently characterized phases) with Cu2+, Mg, Al, Fe3+, Ti4+, Zn, Ca, Na, and K are identified here and 46 of them are endemics of fumarolic formation. Fifty-three of them have been found in active fumaroles at the Tolbachik volcano, Kamchatka, Russia. Thirty different structure types have been established for fumarolic arsenates, including 19 previously unknown among minerals. The alkali-richest (>17?wt% Na2O?+?K2O) and Ti-richest (12–28?wt% TiO2) natural arsenates occur in Tolbachik fumaroles. Nineteen fumarolic arsenates with Cu2+, Al, Fe3+ or Ti contain additional O2- anions. The major fumarolic arsenates at Tolbachik are alluaudite-group members (johillerite, calciojohillerite, nickenichite, bradaczekite and badalovite), lammerite, svabite, tilasite, berzeliite and urusovite. All Tolbachik arsenates crystallized at temperatures =450?°C (the major assumed temperature interval is 500–750?°C), under atmospheric pressure and high oxygen fugacity. They were precipitated directly from the gas phase as volcanic sublimates, or were formed as a result of gas–rock interaction in fumarolic cameras, where the host basalt was the source of the less volatile elements Al, Ti, Mg and Ca. The empirical data on fumarolic As5+ minerals are summarized and discussed, including their chemistry, crystal chemistry (with special attention paid to isomorphic substitutions and solid solutions) and occurrence. Electron-microprobe analyses illustrating the chemical diversity and variability of 53 fumarolic arsenates are given as supplementary data, as well as a photographic documentation of their morphology and paragenetic relationships.

Abstract This paper describes the composition, decay patterns and degradation mechanisms of the building stones and mortars of the Cathedral of Lleida (Catalonia, Spain). Various areas present considerable damage. Four forms of decay are apparent: grain disintegration, joint mortar loss, flaking and efflorescence. The type of stone, its composition and the orientation of the building determine the appearance of the decay forms. The paper analyses these altered mineral forms in the monument, and discusses their possible origin at the level of mineral reactions and stability.

The crystal structure and second world occurrence of the rare selenide brodtkorbite, ideally Cu2 HgSe2, are reported in this paper. Brodtkorbite occurs in the Príbram uranium and base-metal ore district, central Bohemia (Czech Republic) as anhedral aggregates up to 150µm across, in intergrowths with tiemannite and eucairite in a calcite gangue. Other associated minerals include berzelianite, umangite and uraninite. In reflected light, brodtkorbite is cream-white somewhat darker than the associated tiemannite and moderately pleochroic with light pink or bluish tints. Between crossed polarisers, the anisotropy is strong, with violet-grey to yellow-grey rotation tints. Reflectance values in air (R min, R max in %,l nm) are 29.4–36.9 (470), 27.8–34.4 (546), 27.2–33.7 (589), 26.4–33.4 (650). Its average composition (14 electron microprobe analyses) is Ag 0.49, Hg 43.08, Cu 23.86, Se 32.25, Te 0.04, S 0.05, total 99.78 wt%. The resulting empirical formula, on the basis 5 atoms per formula unit (apfu), is (Cu1.87 Ag0.02)S1.89 Hg1.07 (Se2.03 S0.01)S2.04. Brodtkorbite is monoclinic, a 7.5048(12), b 4.1851(9), c 8.0131(12) Å, ß 124.430 (16)°, V 207.59(8) A3, space group P 21/c, Z = 2. The crystal structure of brodtkorbite was solved by the direct method and refined to R = 8.05% on the basis of 416 unique reflections [I> 3s(I)] collected on a Rigaku (Oxford Diffraction) SuperNova diffractometer with an Atlas S2 CCD detector and using MoKa radiation. The crystal structure contains one special position of Hg and two general positions of Cu and Se. The crystal structure consists of layers of edge-sharing [CuSe4] distorted tetrahedra where Cu atoms show a 3 + 1 bond scheme. The [CuSe4] tetrahedra form mackinawite-like layers parallel to (100). The layers show an AA-type of stacking and are connected by linear Se–Hg–Se bonds. Each Cu atom shows three short contacts with three adjacent Cu atoms forming a pseudohexagonal net of metal-metal interactions within one layer. The brodtkorbite crystal structure shows similarities to that of imiterite (Ag2 HgS2), but the two minerals are not isostructural.

Typical characteristics of many anhydrous sulphates of exhalative origin at fumaroles at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia, are the presence of additional oxygen atoms (Oa) in the composition. Recentfield works on the fumaroles of the Second scoria cone in 2014 and 2015 resulted in discovery of a new mineral species, puninite, and collection of fresh alumoklyuchevskite and kamchatkite samples which allowed the re-refinement of crystal structures. The crystal structure of kamchatkite, KCu3O(SO4)2Cl, was solved and refined in Pnmaspace group (a= 9.755(2), b= 7.0152(15), c= 12.886(3) Å, V= 881.8(3) Å3, R 1 = 0.021), whereas alumoklyuchevskite, K3Cu3AlO2(SO4)4, is triclinic, P1 (a= 4.952(3), b= 11.978(6), c= 14.626(12) Å, a = 87.119(9), ß = 80.251(9), ? = 78.070(9)°, V= 836.3 (9) Å3, R1 = 0.049) in contrast to previously reported data. The new mineral puninite, ideally Na2Cu3O(SO4)3, was found in sublimates of Glavnaya Tenoritovaya fumarole. The mineral is named in honor of the Russian crystallographer Yurii Olegovich Punin (1941–2014). Puninite is closely associated with lammerite-ß, tenorite, hematite and anhydrite. Puninite is emerald-green in colour. It is biaxial, optically positive, a = 1.587(2), ß = 1.611(2), ? = 1.649(2), 2Vcalc= 60°. The mineral is soluble in water. The empirical formula of puninite based on 13 O atoms is (Na1.76K0.08)S1.84(Cu2.97Zn0.04)S3.01(SO4)3.02O0.92. Puninite is the first Na-dominant copper oxosulfate mineral observed on Second scoria cone. It is monoclinic, C2/ c, a= 17.41(1), b= 9.39(1), c= 14.40(1) Å, ß = 112.04(7)°, V= 2183(2) Å3, Z= 8. The eight strongest lines of the X-ray powder diffraction pattern are (I-d-hkl): 100-8.058-200, 18.88-6.675-002, 28.47-6.466-202, 14.1-4.398-202, 17.37-4.247- 113, 33.89-3.839- 022, 29.15-2.854- 224, 14.95-2.724- 024. Puninite is structurally related to euchlorine, NaKCu3O (SO4)3and to fedotovite, K2 Cu3O(SO4)3. The unit-cell a parameter value is very sensitive to the K-Na ratio in "euchlorine group" minerals. The crystal structure of puninite (R1= 0.035) is based on oxocentred [O2Cu6]8+dimers. Four sulphate tetrahedra are 'face-to-face' attached to the dimers, whereas the other sulphate tetrahedral groups provide their linkage in two dimensions. The structural architecture of all the copper-oxosulphate exhalative minerals described in this paper can be described as being organized via a "host–guest" principle.

New crystallographic data for holotype potassic-mangani-leakeite, with the ideal composition KNa2 (Mg2 Mn3+ 2Li) [Si8O22](OH)2, are presented. This end-member of the amphibole supergroup was formerly reported as"kornite" by Armbruster et al. (1993a) with the empirical formula (K0.65 Na0.31)(Na1.79 Li0.21 )(Mg2.13 Mn3+ 1.43Fe3+ 0.52Li 0.91)Si8O22(OH)2. X-ray crystal-structure refinements of four crystals taken from the holotype material (Wessels Mine, Kalahari Manganese Field, South Africa) showed that this amphibole composition has the standard space group C 2/ m, contrary to the original report. Differences in chemical composition (Mg vs. Li) were found based on scattering power determined by structure refinement. The crystals tested consistently show compositions significantly different from that reported in the original mineral description, especially as far as the Li content is concerned (0.45–0.85 vs. 1.11 apfu). The new data suggest that the Li content in the original paper is not characteristic of the studied single crystals and may have been overestimated. Three of the investigated crystals, represented by crystal no. 1, a = 9.9603(17), b = 17.830(3), c = 5.3056(9) Å, ß = 105.275(3)°, V = 909.0(3) Å3, yielded a refined composition of (K0.62 Na0.38)Na2 (Mg1.94 (Mn, Fe)2+ 0.36(Mn, Fe)3+; 1.85Li0.85)[Si8O22](OH) 2when using the simplified model without vacancies at the (K, Na)-bearing A site, M (1) and M (2) filled with Mg and (Mn, Fe), and M (3) occupied by Li and Mn. The range of Li at M (3) was bracketed by two models either with (0.64 Li + 0.36 Mg) or with (0.85 Li and 0.15 Mn) having the same scattering power. The choice of the above formula was made considering the agreement between observed and calculated (M (3)–O) bond lengths. On the same grounds, the one crystal with the lowest Li content of 0.46 apfu belongs to the compositional space of eckermannite. Small concentrations of A group vacancies cannot be excluded.

The aim of this paper is to identify the mechanisms responsible for the chromatic alteration of Pietra Serena sandstone, the stone used in Florentine Renaissance architecture. This stone has a bluish-grey colour when fresh, but is often oxidized acquiring an ochre-brown or reddish colour on buildings. A mineralogical, chemical, petrographic and physical characterization was carried out on the blocks of Pietra Serena used for the Waldensian Church, located in the centre of Florence, showing a characteristic reddish colouring, and on samples from the quarry from which these blocks were extracted. Micro-Raman and SEM-EDS analyses were performed on the red surfaces of the samples in order to highlight the mineralogical and chemical transformations. The results confirmed that the chromatic alteration of Pietra Serena is caused by the mobilization of Fe2+ (prevalent in the clay minerals that make up the matrix of this sandstone and in aluminosilicates such as biotite), which is easily oxidized to Fe3+ in an oxidative environment. This is a consequence of a particular condition of decay, such as the presence of water, CO2, low pH.

Monohydrocalcite (MHC, CaCO3 · H2O) is a thermodynamically metastable phase relative to calcite and aragonite in aqueous solution. Although MHC occurs broadly in organisms, little information about its biogenic origin is available. In this paper, a series of amorphous calcium carbonates (ACCs) with different Mg2+ contents were first synthesized in the presence of polyaspartic acid (PASP), and the phase transformations of the PASP-regulated Mg-ACCs (PASP-Mg-ACCs) were then studied under different medium conditions. The structure, morphology and composition of the precursor PASP-Mg-ACCs and transformation products were investigated by using a wide range of techniques, including XRD, FT-IR, FESEM, TG-DTA,13 C NMR and ICP-AES. Our results show that PASP-Mg-ACC with 24.71 mol% Mg2+ can be transformed into MHC, without formation of hydromagnesite or other hydrated magnesium carbonates, whereas the PASP-Mg-ACCs with <24 mol% Mg2+ resulted in magnesian calcite and aragonite. Time-course transition experiments unveiled that the transformation from PASP-Mg-ACCs to crystalline phases proceeds through the dissolution of the initial precursor PASP-Mg-ACCs and the subsequent crystallization of the secondary mineral phases. The formation of different secondary minerals depends not only on the Mg2+ but also on the PASP content in precursor PASP-Mg-ACCs. Because of the exclusive formation of MHC from PASP-Mg-ACC under current biomimetic conditions, biomacromolecule-regulated Mg-ACC may act as the transient precursor and be responsible for the biogenesis of MHC. The current results contribute to the elucidation of the biogenic origin and role of MHC in nature.

The chlorites are good indicators of rock history because their wide compositional variations are sensitive to the formation conditions, like pressure (P), temperature (T), redox state, fluid composition. Accordingly, many geothermometers based on their composition, either empirically or thermodynamically, have been proposed during the last 30 years, especially in low-temperature contexts (T < 350 °C). This paper presents a graphical tool that considerably facilitates the use of two of the most recent chlorite thermometers for low- and very-low-T chlorites. The temperature–composition relationships for low-T chlorites are represented in T–R2+–Si diagrams, allowing chlorite compositions to be predicted as a function of temperature or, conversely, temperature to be estimated from compositional fields of natural chlorites. This graphical projection is based on a comparison of the parameters (ideal chlorite compositions and calculated T) predicted by geothermometers with analyses of natural chlorites for which independent T estimates are available over a range of geological environments. The new T–R2+–Si diagram provides a practical tool for thermometric purposes in the applicability range of the considered models, in particular for diagenesis and low-grade metamorphism.

The paper presents the first data on the crystal chemistry of the cation-exchanged forms of layered titanosilicates belonging to the epistolite group. It was found that these heterophyllosilicates have high exchange capacity and selectivity for cations of chalcophile elements (Ag, Cu and Zn) and could be considered as potentially novel raw materials or, more likely, as possible prototypes of cation-selective synthetic microporous materials. The crystal structures of Ag- and Cu-exchanged forms of lomonosovite and Ag-exchanged form of murmanite were studied by single-crystal X-ray diffraction. The topology of the main structural unit, the HOH block, remains unchanged in cation-exchanged forms as compared to the initial lomonosovite Na4Ti4 (Si2O7)2O4 · 2Na3PO4 (P-1) and murmanite Na4Ti4(Si2O7)2O4 · 4H2O (P-1). In Ag-exchanged murmanite, Ag cations occupy two crystallographically non-equivalent positions: one in the heteropolyhedral (H) sheet and another one in the octahedral (O) sheet corresponding to the positions of Na in initial murmanite. The crystal structure of the Ag-exchanged form of lomonosovite is characterized by an increased unit-cell parameter c and doubled parameter b as compared to initial lomonosovite. Ten large-cation sites statistically occupied by Ag and Na correspond to the Na sites in the initial lomonosovite: six in the interlayer space, two in the H sheet and two in the O sheet. Silver significantly replaces Na in sites in the interlayer space and in the O sheet, whereas sites in the H sheet are less affected by the ion exchange. Unit-cell parameter c of the Cu-exchanged form of lomonosovite decreases by 3.58 % as compared to the initial lomonosovite whereas a and b remain almost the same. The Cu cations occupy two crystallographically independent positions. The Cu(1) site, corresponding to the Na(3) site in the initial lomonosovite, is located in the interlayer space. The low-occupancy Cu(2) site is located on the inversion centre in the O sheet; this site is vacant in the initial lomonosovite. The Cu(2) site is surrounded by six O atoms forming an octahedron distorted due to the Jahn-Teller effect.

Neutron scattering and neutron imaging are powerful techniques for studying the structure of objects without damage, which is an essential prerequisite for investigations in Cultural Heritage domain, particularly in Archaeology. The deep penetration of neutrons in most materials allows for the study of relatively large objects. The contrast between similar materials, like metals in alloys, or that due to the presence of hydrogen atoms gives information about the internal structure of objects that have been modified or repaired in the past. Imaging and tomography give a 3-dimensional view of the whole object, permitting discrimination between different parts of the object, voids, water content and large pores. Neutron scattering also provides information about elemental composition as well as about tiny pores and quantitative evaluations of the total area of internal surfaces or water content. The paper is an introduction to these techniques, which are easily accessible at neutron facilities.

Nuclear Magnetic Resonance (NMR) can be successfully applied to a wide number of organic, inorganic, and hybrid materials regarding cultural heritage. High-resolution solid-state NMR provides information on the structure of materials, and portable NMR devices allow non-destructive and non-invasive in situ investigation of variably sized objects. This result is possible by combining open magnets and surface radiofrequency coils to generate a sensitive volume external to the sensor and inside the object under investigation. In this paper we focus on the application of NMR to investigate inorganic porous materials such as pottery, plasters, and stones from cultural heritage sites. 27Al MAS and 3QMAS, and 29Si MAS high-resolution solid-state NMR along with spectral deconvolution allowed for the investigation of the chemical structure of ancient pottery. Portable unilateral NMR was used to investigate, in a non-invasive and non-destructive way, the porous structure of pottery. The effect of protective-consolidating treatments on plaster was carefully investigated by 1H NMR depth profiles that allowed for scanning with micrometric resolution of plaster specimens. Changes occurring in the total open porosity after treatments were also evaluated. NMR diffusion measurements provided information on the restricted geometry of the porous structure of two types of biocalcarenite and tuff. A suitable processing of collected data enabled us to define the average pore radius and pores' interconnection in these materials.

The Koktokay No. 3 pegmatite is the largest Li-Be-Nb-Ta-Cs pegmatitic rare-metal deposit of the Chinese Altai orogenic belt, and is famous for its concentric ring zonation pattern (nine internal zones) and rare-metal reserves. In this paper, we present the results of major and trace element analysis for garnet, tourmaline, and beryl from the outer to inner zones of the No. 3 pegmatite. From previous studies on tourmaline and beryl, potential tracers of the degree of pegmatite evolution could be found by comparing with accepted indicators and evolutionary trends from the outer to inner zones of this pegmatite. The Sc, Y, Li, Ta contents and Y/Ho value of garnet, together with the Ti, Ca, Na, Pb, Bi and REE contents of tourmaline, and the Fe, Ga and Rb concentrations of beryl could be possible tracers of the degree of evolution of pegmatites. The textures and internal structures (homogeneity, oscillatory pattern, heterogeneous rims, replacement structures) of minerals in the pegmatite suggest that the rock underwent (1) rapid undercooling and crystallization after emplacement, resulting in the formation of an unidirectional solidification texture (UST), and then (2) became relatively stable, forming coarse crystals in outer zones, and finally (3) experienced disequilibrium crystallization, leading to the formation of complex internal structures of minerals in the inner zones, mainly caused by exsolution of more fluid and the formation of immiscible melts with different alkali contents. The evolutionary trend and the internal structures of tourmaline and beryl indicate that the formation of the Koktokay No. 3 pegmatite was controlled mainly by fractional crystallization. The convex tetrad effect, non-CHARAC Y/Ho values, and extreme Eu depletion of garnet suggest that immiscibility, which is a significant mechanism during the formation of the No. 3 pegmatite, occurred during emplacement. The differences in composition and internal structures of the minerals between the outer and inner zones of the No. 3 pegmatite suggest that there was an abrupt change, during transition from the melt stage to the melt–fluid stage, resulting from a decompression event, which led to the exsolution of the fluid and initiated the Li-Ta-Cs deposition in the pegmatite.

This paper analyses the efficacy of dispersions of nanoparticles of calcium hydroxide for consolidating lime mortars, according to three variables: the type of dispersion (three consolidating compounds—CaLoSil®, Nanorestore® and Merck®—with different-sized calcium hydroxide particles); the concentration of the dispersion (5 and 25 g/L of Ca(OH)2 in isopropyl alcohol); and the state of the sample (comparison of saturated and non-saturated samples). The outcome of the consolidation process was studied in terms of improved carbonation of the mortar, mineralogy (by means of X-ray diffraction and thermogravimetric analyses), texture (study of the porosity by mercury intrusion porosimetry) and compactness (measurement of ultrasonic velocity propagation through samples). To ensure that the treatment had no negative effects on the physical characteristics of the mortars, we performed microstructural (phase morphology studied by means of scanning electron microscopy) and aesthetic (colour and lightness measured by spectrophotometry) analyses. Of the different dispersions, CaLoSil® at 5 g/L produced the most significant improvement in the degree of carbonation and in the compactness of the mortar, thanks to the precipitation of small crystals of calcite and aragonite in the pores located between the matrix and the aggregate grains. This product also caused the least significant chromatic changes (slight decrease in lightness and yellowing) and the greatest increase in ultrasonic propagation velocity through the mortar samples. This research has specific application in restoration work that involves consolidation of lime mortars, especially in tropical climates or in confined environments with high humidity levels (such as deep hypogea).

This paper presents the photoluminescence and EPR experiments performed on two varieties of diamond crystals from the Sytykanskaya pipe: small crystals which were inclusions in the ancient olivines, and large sized specimens. Small crystals and the cores of large crystals contain B and P2 nitrogen defects whereas the outer zone of large diamonds includes A nitrogen centers and their derivatives with vacancies. Coatings of large diamonds are a product of a second step of crystallization. The interpretation of data obtained proposes that small crystals from Sytykanskaya pipe are the most ancient of the Yakutia province, and that the generation of the P2 centers is a result of B centers destruction during early plastic deformation.

This paper is focused on defining the geographic provenance of eight marble tesserae of archaeological interest used for the opus sectile floor slabs of the Villa con ingresso a protiro, located in the Roman underwater Archaeological Park of Baia (Naples, Italy). Geochemical, isotopic and petrographic data show that Carrara, Thasian and Docimium/Afyon marbles were used in manufacturing the mosaic constituting the floor slabs of the Roman Villa.

Process limitations have thus far prevented mineral carbonation of alkaline wastes from been widely applied. These barriers are caused by inefficient processing, but also by mineralogical aspects inherent to the materials. Better understanding and predictability of the effects of mineral carbonation on alkaline materials could be obtained by studying the carbonation susceptibility of constituent minerals separately, allowing for detailed and accurate analysis of their reaction kinetics and maximal conversions and of the carbonate products formed. For this purpose, this paper presents the synthesis and carbonation of the seven most abundant alkaline minerals found in AOD, CC and BOF slags, namely: a?kermanite (Ca2MgSi2O7), bredigite (Ca7Mg(SiO4)4), cuspidine (Ca4Si2O7F2), ?? and ??C2S (Ca2SiO4), merwinite (Ca3Mg(SiO4)2), and srebrodolskite (Ca2Fe2O5). Two experimental approaches to mineral carbonation of increasing levels of process severity are utilized: (mild) incubator carbonation, and (accelerated) pressurized slurry carbonation. In addition, the slags and two free oxides (CaO and MgO) are equally carbonated and evaluated. Data regarding CO2 uptake, mineral conversion and formed carbonate and non-carbonate products in the samples were obtained through TGA, QXRD (Rietveld refinement) and SEM techniques. Reduction in material basicity and evolution of particle morphology were also assessed. The synthesized mineral purities (>70 wt% target mineral phase) were found sufficient for more accurate assessment of carbonation behaviour of the individual minerals. Bredigite was found to be the most reactive mineral under all processing conditions; C2S and wollastonite were more reactive under slurry carbonation, while srebrodolskite and calcium monoferrite were found to be more reactive under moist carbonation. Merwinite and diopside had the slowest carbonation conversions. Calcite and aragonite were the dominant carbonate products formed, whereby aragonite formation was promoted in Mg-containing materials. The morphology of aragonite crystals and the packing density of its product layer were found to vary depending on the parent mineral. Characteristic slag carbonation products, not observed as extensively from synthetic mineral samples, were magnesian calcite from slurry carbonation, and monohydrocalcite and vaterite from moist carbonation. Wollastonite was the main crystalline non-carbonate product, occurring predominantly from slag carbonation, while silica-rich amorphous matter formed in all samples proportionally to CO2 uptake. Free lime, when present, controlled material basicity above pH 12, while silicates were found to typically possess pH in the range of 11.3?11.9, and Ca-carbonates eventually controlled the pH of well carbonated samples to values under 10.

Nuclear quadrupole resonance (NQR), nuclear magnetic resonance (NMR) and nuclear gamma-resonance (NGR or Mössbauer Effect) methods are generally described as highly sensitive tools in studies of local electronic structure and symmetry in solid-state materials. This is due to high informativity in electronic structure investigations, high resolution in phase-structural diagnostics (down to nano-scale), possibility to study polycrystalline and complex compounds, and to the non-destructive character of these methods. As applied to Earth sciences, both NQR/NMR and Mössbauer spectroscopy methods contribute to mineralogical material science and mineral physics. Another important aspect is the fact that these methods, as demonstrated recently, belong to unique techniques suitable for on-line bulk mineralogical analysis. This includes remotely operated sensors used with conveyor systems in mining/materials handling and similar applications where real-time data collection/processing provides significant commercial benefits. These developments open new pathways for NQR/NMR and Mössbauer spectroscopy applications. Notably, NQR/NMR and Mössbauer effects are observed primarily on different nuclei-probes but provide similar information about the local properties of materials (hyperfine fields, electric field gradients and relaxation effects). This makes NQR/NMR and Mössbauer methods mutually complementary despite their significant technical differences. This paper includes examples of recent applications of NQR, NMR and Mössbauer spectroscopic tools to studies of copper-, antimony- and iron-containing sulfides, demonstrating how these methods can contribute to an improved understanding of geochemical problems.

An unique mineral assemblage (graphite + wüstite + wagnerite + sarcopside + monazite-(Ce) + xenotime-(Y) + chlorite), included within fluorapatite, was identified in the S-type Caledonian Rumburk granite, Czech Republic. Graphite appears as a finely dispersed phase within apatite and other minerals and as interstitial flakes in the rock matrix; it is probably of restitic origin related to anatectic melting. Wagnerite, wüstite, monazite-(Ce), and xenotime-(Y) are commonly intergrown, indicating their cogenetic formation. Magmatic fluids, equilibrated with graphite, caused partial metasomatism of early-formed fluorapatite and triggered the formation of wüstite and the various phosphate-mineral inclusions within alteration domains in the apatite host (by dissolution-reprecipitation). The formation of wüstite was facilitated by the coexisting graphite, which maintained the required low oxygen fugacity, and the apatite host, which provided a silica-undersaturated environment. The lower temperature limit of the alteration event is defined by the wüstite stability field (>570 °C). Representative mineral formulae are Fe2+0.67Fe3+0.220.11O (wüstite), (Mg0.87Fe0.97Mn0.15)S=1.99(PO4)(F0.64OH0.36) (wagnerite), and (Fe2+2.27Mg0.45Mn0.19)S=2.91(PO4)2 (sarcopside). The results of this study improve knowledge about the natural occurrences of wüstite and wagnerite and their paragenetic relations; they permit additional insights into mineral-forming processes in granitic magmas under strongly reducing conditions. This paper provides the first record of wüstite occurring in granite.

This paper documents the occurrence of tinsleyite in the ''dry'' Cioclovina Cave, Sureanu Mountains, Romania. This is the first mention of tinsleyite as a cave mineral and the second find of this mineral species in the world. The mineral occurs in small quantities, as a rare authigenic, early diagenetic mineral, in the bat guano deposits in this cave. Low (alpha) quartz is the only closely associated mineral. This assemblage corresponds to a possible reaction in the natural guano-clay system upon decomposition of illite. Chemical analyses show variable leucophosphite contents (up to 31.68 mol.%). The unit-cell parameters calculated for an iron-poor sample are a = 9.638(5) Å, b = 9.522(4) Å, c = 9.540(4) Å and ß = 103.10(3)°, whereas those determined for an iron-rich sample are a = 9.639(6) Å, b = 9.538(8) Å, c = 9.553(7) Å and ß = 103.04(4)°. Thermal analyses show that water is lost in three steps and that the loss of molecular water is complete before 250°C. The fully dehydrated material is completely X-ray amorphous. Ammonium is expelled at about 490°C. The infrared spectrum of tinsleyite affords reasonable evidence for the presence of PO4, NH4 and OH groups, together with H2O molecules. The punctual symmetry of the PO4 groups is Cs.

Shock metamorphism is a fundamental process in the solar system. It is evidenced by craters on the surfaces of solid planets and asteroids, as well as by shock-induced microstructural modifications in minerals. This paper presents review of the main microstructural characteristics of shock signatures in meteoritic minerals (olivine, enstatite, diopside, plagioclase and metal) as evidenced by transmission electron microscopy (TEM). The nature of the shock-induced modifications strongly depends on the material and the shock conditions (peak pressure and peak temperature). It includes fracturing, dislocations and twins (evidence of plastic deformation), phase transformation to high pressure polymorphs, amorphization, recrystallization, melting and volatilization. The influence of shock-induced microstructures during post-shock events is also discussed and further research tracks on the microstructural aspect of shock metamorphism are outlined.

Gypsum alabaster is being used to realise works of art since ancient times. In Italy, a number of quarries exploiting Messinian outcrops (in particular in Sicily and Tuscany) are known since the Etruscan period, and the Opificio delle Pietre Dure of Firenze posed the question to geochemically characterise these in order to recognise the provenance area of raw materials. In this paper, a discrimination was attempted using Pb isotopes because of 1) the low residence time of this element in seawater, and 2) the supposed interaction between Tuscan alabasters and hydrothermal fluids of known Pb-isotope composition. Textures indicate that de- and re-hydration reactions after deposition actually affected alabaster involving fluids circulation. Pb-isotope data are scattered (206Pb/204Pb = 17.88-18.71, 208Pb/204Pb = 38.01-38.86, 207Pb/204Pb = 15.58-15.76) suggesting that: 1) fluids did not drive any compositional homogenisation; 2) the isotopic signature is inherited from the evaporitic sedimentary environment and reflects a complex hydrology of the Messinian evaporitic basins; 3) Pb isotopes are an unreliable marker because of the compositional overlap between Tuscan and Sicilian samples. However, at odds with the general trend of their large scattering, the collected data suggest a relative homogeneity at the local scale.

Abstract The standard chemical potentials µ0s of aqueous solutes over a wide range of temperatures and pressures are needed to calculate phase and chemical equilibria in hydrothermal systems. The standard derivative thermodynamic properties of solutes such as enthalpies, heat capacities and volumes can be integrated to calculate µ0s at superambient conditions. These derivative properties can be obtained by extrapolation to infinite dilution of calorimetric and volumetric data for aqueous solutions measured as a function of concentration at various temperatures and pressures. A large amount of new experimental results has been reported over the past two decades, which allowed improvement of predictions based on equations of Helgeson, Kirkham and Flowers, among others. Several new thermodynamic models for the standard thermodynamic properties have been proposed during this period. This paper focuses on non-electrolyte solutes and provides an overview of the recent sources of experimental data. We also compare the ability of several thermodynamic models to correlate and predict µ0s

Abstract Clinotobermorite, Ca5Si6O17•5H2O, is a rare mineral, structurally related to tobermorite 11 Å. It is characterized by the presence of structural disorder (evidenced by the diffuseness of the reflections with k odd) which, until now, prevented the determination of its real structure. In this paper, a model for the real structure of clinotobermorite is proposed on the basis of OD theory, through examination of the X-ray diffraction pattern of a sample coming from the Wessels mine (South Africa). The proposed model, which assumes the presence of silicate double chains of wollastonite-type, is confirmed by structural refinements carried out for the two polytypes with maximum degree of order (MDO). The MDO1 polytype of clinotobermorite (monoclinic, space group Cc, a = 11.276(2), b = 7.3427(8), c = 22.642(4) Å, ß = 97.28(1)°) was refined up to R = 0.15, whereas the two refinements performed on the MDO2 polytype (triclinic, space group C1, a = 11.274(2), b = 7.3439(7), c = 11.468(2) Å, a = 99.18(1), ß = 97.19(1), ?= 90.09(1)°) converged to R = 0.12 and R = 0.10, respectively. In clinotobermorite infinite calcium polyhedral layers parallel to (001) are connected through double silicate chains [Si6O17]10- running along b; additional calcium cations and H2O molecules are placed in the channels of the resulting framework. By dehydration at 225°C, clinotobermorite transforms topotactically into a new phase, which also displays an OD character. The results of the structural refinement carried out for its triclinic MDO2 polytype (space group C-1, a = 11.156(5), b = 7.303(3), c = 9.566(5) Å, a = 101.08(4), ß = 92.83(5), ? = 89.98(4)°) indicate that this phase, with crystal chemical formula Ca5Si6O16(OH)2, exhibits single chains of wollastonite-type, resulting from decondensation of the double chains. On the basis of the new detailed structural information a possible explanation for the enigmatic thermal behaviour of tobermorite 11 Å has been proposed

Abstract This paper relates the finding of stoppaniite, a new mineral of the beryl group, at Capranica, Vico volcanic complex, Latium, Italy. Stoppaniite occurs inside the miarolitic cavities of a volcanic ejectum, as very rare, transparent, light-blue, hexagonal-prismatic euhedral crystals, up to 0.5 mm in length. It is optically uniaxial (-), and shows a weak pleochroism from colourless to very light blue. The refraction indices are: e = 1.619(3) and ? = 1.625(3); the density is: Dobs = 2.79(3) g/cm3, Dcalc = 2.811 g/cm3. Stoppaniite is hexagonal, s.g. P6/mcc, with a(Å) = 9.397(1), c(Å) = 9.202(2). Strongest X-ray powder diffraction lines (Gandolfi camera) are (d in Å, intensities visually estimated): 3.278 (vS), 8.12 (S), 2.903 (S), 4.00 (m), 2.553 (mw), 1.752 (mw). The empirical crystal-chemical formula is: (Fe3+2.70Mg0.64Al0.42Mn0.06Ti0.02Sc0.02)(Be6.88Si11.60)O36*2H2O(Na0.94K0.02Cs0.02) compatible with the simplified formula: (Fe3+)3(Mg,Fe2+)Na(Be6Si12O36)*2H2O, or ideally Fe3+ 4Be6Si12O36. A rational classification of beryl group minerals based on the octahedral occupancy is proposed.

Abstract This paper describes the occurrence of Th-rich hellandite-(Ce) and britholite-(Ce) within a volcanic ejectum from a pyroclastic formation of the Vico volcanic complex, north of Rome, Italy. The host rock is a saturated alkali-syenite which consists mainly of potassium feldspar and plagioclase, together with fluor-biotite, plagioclase, titanite, clinopyroxene and magnetite. Hellandite-(Ce) and britholite-(Ce) are associated with this mineral assemblage which contains also several accessory phases including zircon, fluorapatite, allanite, and silico-phosphates of Th, U, REE close in composition to cheralite-brabantite. Hellandite-(Ce) and britholite-( Ce) are typically intergrown with hellandite in all case observed rimming britholite. These unusual REE, Th, U minerals are secondary to the formation of the host rock and the compositions of the associated minerals suggest that they originated from fluids rich in F, P, and possibly S and C. The presence of fractures filled by clays containing dispersed REE-minerals, probably fluorocarbonates, suggests a very late-stage hydrothermal remobilization, transportation and redeposition of the REE. An important implication of such widespread secondary mineralization is that great care should be exerted when using bulk-rock trace-element data from these volcanic samples for geochemical modelling.

Abstract This paper describes a hydrothermal alteration sequence in the Soultz-sous-Forets granite (Alsace, France) and presents an interpretation of its origin, based upon petrographic observations, microthermometric measurements and mass-balance calculations. The alteration results from interactions between the granitic basement and sedimentary fluids which have circulated through the fracture network. The main stages of alteration observed in the studied zone are: total dissolution of primary quartz on both sides of a fault; complete transformation of oligoclase into tosudite in the presence of organic matter; precipitation of hairy illite, calcite and quartz in veinlets. The temperature during these events appears to have decreased from the tosudite stage (T ‹ 400°C) to the illite-calcite-quartz stage (140°C). Assuming tosudite is a geochemical analog of kaolinite, the nature and chronology of the alteration sequence show similarities with the diagenesis of some kaolinitic sandstones: clay enrichment in plagioclase by acidic organic fluids, metastable coexistence of aluminous clays (tosudite here instead of kaolinite in sandstones) with K-feldspar and quartz, and post-illitization of the clay fraction promoted by the circulation of brines. The preservation of orthoclase during these alteration stages reinforces the assumption that the reaction K-feldspar + Al-clays ? illite + quartz can be inhibited in natural environments, depending on the nature of the clay. A major difference between this alteration sequence and diagenetic reactions is that it proceeds with decreasing temperature. This implies that the fundamental parameter controlling the alteration sequence observed here is the chemistry of the fluids.

Abstract This paper reports the discovery of new localities of diagenetic faujasite, occurring with phillipsite and chabazite in Quaternary tuffs in north-east Jordan. The distribution of zeolites shows a vertical zonation of a previously undescribed type, in which a phillipsite-chabazite zone occurs at the top and is underlain by a faujasite-phillipsite zone. It corresponds to the sequence of zeolite crystallization: faujasite-phillipsitechabazite. Faujasite is more abundant in the tuffs of the lower zone than at any other locality described hitherto, constituting up to 30 % of the rock. The faujasite occurs as octahedral crystals between 50 and 300 µm in size. At Jabal Aritayn, two generations of faujasite occur in the same sample. The first generation occurs as a lining to cavities and is characterized by a low K content, whereas the second generation occupies the central part of cavities and has a higher K content. The second type is richer in K2O than faujasite from any previously known locality (up to 2.93 %). The Si/(Si+Al+Fe) ratio of the Jordanian faujasites varies between 0.695 and 0.718. The formation of faujasite and the other zeolites is attributed to the alteration and leaching of sideromelane in an open hydrological system by percolating meteoric water.

Abstract The equilibrium between garnet-cordierite and orthopyroxene-sillimanite-quartz assemblages is of fundamental importance in constructing the phase relations of metapelitic granulites. Previous studies have inferred widely differing forms, pressure-temperature positions and dP/dT slopes for the reaction. The experiments presented here show that, for the KFMASH system, the reaction is grt + crd + kfs + qz = opx + sil + L, running from left to right with increasing pressure. The reaction extends from 900 (± 10)°C, 8.9 (± 0.3) kbar to 950 (± 10)°C, 7.8 (± 0.4) kbar, i.e. it has a negative dP/dT. Comparison with previous data shows the vital importance of accounting for the volatiles contained in cordierite and shows that the high-pressure stability limit of volatile-undersaturated cordierite is between that for volatile-saturated cordierite and volatile-absent cordierite. Natural assemblages are modelled most closely by experimental studies involving volatile-undersaturated cordierite, with the experimental data of this paper being most applicable to mineral assemblages low in carbon dioxide and calcium. The data of Hensen & Green (1970, 1971, 1972, 1973) are more suitable for natural assemblages high in carbon dioxide and calcium. Both sets of data constrain the reaction to lie between 8.0 and 11.0 kbar at 900°C and therefore, the occurrence of the orthopyroxene-sillimanite-quartz assemblage should not be taken as a necessary indicator of metamorphic pressures in excess of 11 kbar (Bertrand et al., 1991).

Abstract A mineral is an element or chemical compound that is normally crystalline and which has been formed as a result of geological processes. The IMA Commission on new Minerals and Mineral Names (CNMMN) defines in the present paper the exceptions to the general definition that should be permitted

Abstract A crystal-chemical database for natural garnets has been developed at the CSCC, Pavia. It presently consists of 281 garnets representative of common chemical compositions and petrogenetic conditions. For most samples, X-ray single-crystal structure-refinement and SEM-WDS analysis were done on the same crystal. Ionmicroprobe analysis for detection and evaluation of H, Li, Be, B was also done in some cases; spectroscopic techniques were used to confirm the presence of unusual substitutions. This combined approach allowed detection and characterization of substitutions occurring in natural garnets. Plots of atomic coordinates and geometrical parameters as a function of the unit-cell edge show that garnet crystal-chemistry is characterized by the presence of strong inductive effects and non-linear behaviour, the quantitative aspects of which are discussed in the companion paper. There are stringent structural constraints on chemical variability due to the extensive edge-sharing between adjacent polyhedra. These phenomena, which make the correct determination of site populations a non-trivial task, have now been analyzed in detail and fully understood. We present here an automatic procedure which allows the determination of reliable site-populations starting from the results of the structure refinement. It is based on multiple regression equations for the independent estimates of each cation content and on their subsequent normalisation according to crystal-chemical constraints

Abstract The first reproducible synthesis of diamond under metastable conditions was achieved reproducibly by Eversole at Union Carbide Corporation in the early 195O's, even before the high-pressure high-temperature (HPHT) experiments at General Electric were successful. Nevertheless, it has taken almost 30 years for the scientific-technical community to be generally convinced of the feasibility of continuous low-pressure diamond growth from activated gas phases. Since then, however, diamond chemical vapour deposition (CVD) technology has progressed considerably: a multitude of deposition processes are now available to grow diamond films, while textured and hetero-epitaxial (on Si) deposition has also been achieved. New technological applications of diamond films, which make use of their outstanding physical properties, are continuing to emerge. Simultaneously, there has been rapid progress in the understanding of which molecular species and physico-chemical processes are relevant for CVD growth of the metastable diamond phase, mainly due to the development of data-bases of chemical gas phase reactions in C-H-O systems using results of research on flames and combustion. This paper intends to give a short overview of the growth processes and different applications of diamond films.

Abstract The paragenesis of Y, Th, U, Zr and REE accessory minerals (monazite, apatite etc.) in four different late-Variscan granitic associations of the Sierra de Guadarrama are discussed. Characteristic accessory mineralogical paragenetic sequences are found in each association. The occurrence of different minerals is controlled by the initial trace-element contents of the melt, the aluminous index, the Ca content and volatiles, as well as (F, P) contents, ƒO2 and the LREE/HREE, Th/REE, U/REE and U/Th ratios of the melts. The accessory mineral assemblages can be changed by post-magmatic hydrothermal processes. The differences between the accessory mineralogical paragenesis and the individual mineral compositions in the granitic rocks are discussed using these parameters, which play a key role in determining the crystallization of accessory REE, Th and U-bearing phases in the studied granitoids. The paper also discusses the geochemical behaviour of these elements during granite petrogenesis.

Abstract This paper reports the results of a combined methodological study performed on tetraferriphlogopite from the Araxà carbonatite. We compare Mossbauer spectroscopy and X-ray absorption near-edge spectroscopy (XANES) results to previously reported single-crystal X-ray and electron microprobe analysis data (Cruciani & Zanazzi, 1994). The combined techniques provide evidence for the presence of a remarkable amount of tetrahedrally coordinated Fe3+ in this sample, and show that high OH content in tetraferriphlogopite is compatible with the large Fe2O3/FeO ratio inferred from the chemical and spectroscopic data.

Abstract The equilibrium curve 2 diaspore = corundum + H2O was experimentally investigated by reversal runs in a piston-cylinder apparatus in the pressure range 15 kbar-50 kbar. Its position is determined by reversal brackets at 15 kbar (488-519°C), 25 kbar (581-600°C), 30 kbar (629-648°C), 40 kbar (675-696°C), and 50 kbar (695-719°C), thus lying between the curves reported by Kennedy (1959) and Matsushima et al (1967). In addition, the behaviour of diaspore during heating at one atmosphere was determined using a Guinier camera with heating device. The resulting regression function for the volume has a higher slope in temperature than the function estimated by Berman (1988). Using this newly determined function to describe the thermal expansion of diaspore, the measurements of the isothermal compressibility of this phase performed by Xu et al (1994), and the other thermodynamic data provided by Berman (1988), the calculated curve fits the reversals presented in this paper rather well.

Abstract This paper deals with a crystal-chemical, infrared spectroscopic study of monoclinic epidotes from Praborna (St. Marcel, Val d' Aosta, Italy). The studied samples range in composition from clinozoisite (Czo) to Sr-rich piemontite (Pm). In the OH-stretching region, (Al,Fe3+)-clinozoisites show a single broad band centred in the range 3345-3380cm-1 which is assigned to the [M2]Al-O10 ? H...O4-[M1'3](Al,Fe3+) configuration. The spectra of Sr-rich piemontites show a well-resolvable doublet at almost constant wavenumbers (3417/3454 cm-1) which can be explained by two simultaneous effects: (i) the entry of Mn3+ in the non-OH-coordinated M3 octahedra and, (ii) the entry of Sr substituting for Ca in A2.

Abstract The famous association of metagabbros, eclogites, glaucophanites, jadeite rocks and ultramafics from the island of Syros forms a distinct lithostratigraphic or tectonic unit. It is interpreted as a high-pressure metamorphic ophiolite suite. This paper provides geochemical and Sr-isotope constraints on the geotectonic setting in which the magmatic protoliths of the Syros metabasites were formed. A compositional gap exists between the metagabbros with Mg-numbers [Mg# = Mg/(0.85Fetot + Mg) atomic ratio] of 0.75-0.88 on the one hand and eclogites and garnet-glaucophanites on the other hand with Mg# of 0.35-0.62, and maximum total iron contents of up to 18 wt.% FeOtot. Metagabbros from various localities and glaucophanites collected around Manna form geochemically coherent groups with smooth correlations between compatible as well as immobile incompatible elements and Mg#. By contrast, the behaviour of immobile incompatible elements, and to some extent also of compatible elements, is highly unsystematic in the eclogites and garnet-glaucophanites. Also, the more mobile elements display a wide scatter in all rocks. This, in conjunction with the unsystematic variation of Sr-isotopes, is thought to be due to secondary alteration. From the strong correlation of Ni and Cr with Mg# and the flat REE patterns lacking Eu-anomalies, a cumulus nature is inferred for olivine, clinopyroxene, and spinel, associated with intercumulus formation of plagioclase in the magmatic protoliths of the metagabbros. There is no direct genetic link between these rocks and the precursors of the Manna-type glaucophanites with REE characteristics typical of N- to T-type MORB. The extremely high geochemical diversity of the eclogites and garnet-glaucophanites from Syros favours individual evolution of their protoliths in small magma bodies as suggested for superferric eclogites from the Western and Ligurian Alps, as well as the ferrogabbros from the ophiolites of the Northern Apennines. From the geochemistry of the Syros metabasites along with the initial 87Sr/86Sr ratios of the metagabbros between 0.7031 and 0.7033, as well as an eNd value of 7.7 from a garnet glaucophanite, the magmatic protoliths are inferred to have formed in a back-arc setting. By analogy to the association of gabbros and ferrogabbros adjacent to the Atlantis II fracture zone of the SW Indian Ridge, we further suggest an origin at a spreading ridge in proximity to a transform fault.

Abstract A series of rocks collected from a single lava flow near Lake Bracciano (Rome) shows progressive stages of analcimization. This paper presents a chemical study of these rocks with calculations of gains and losses from the bulk-rock chemical composition based on atomic percent. With increasing alteration, Na increase is counterbalanced by a decrease in K, Ca and Mg; total iron content is constant but ferrous Fe increases. Mineral phases, either as phenocrysts and/or as laths present in the volcanic groundmass, have been analyzed by EMPA. In addition to leucite altered to analcime, feldspars and pyroxenes converge towards close composition with progressive analcimization. Plagioclases reach labradorite-bytownite compositions and a ternary Na-Ca-K member develops. Chemical variations observed either in bulk-rock composition or among minerals suggest that the analcimization process occurs in an open, reducing environment and that a partial rearrangement of alkalis occurs within the rock. Analcimization also appears to be linked to the rapid cooling of the rock and to the formation of zeolites which are subsequently transformed into analcime.

Abstract This paper presents trace element and Sm-Nd isotope data on the Mönchalpgneiss in order to compare the geochemistry of the two polymetamorphic igneous suites that comprise over 30% of the Austroalpine Silvretta nappe. The first are the so-called "Younger Orthogneisses" of the "Fliielagranitic Association" and the second are the "Older Orthogneisses" including the Mönchalpgneisswhich are associated with metagabbros, metadiorites, metatonalites and metagranitoids. U-Pb zircon results from the Mönchalpgneiss are indicative of anatectic processes in late Cambrian to Ordovician times. A volcanic-arc (VA) tectonic environment during intrusion explains the direct association of gabbroic and metagranitoid rocks in the Engadine area. This model is in line with the distribution of major, trace and rare earth elements in these anatectic rocks. However, the significance of the geochemical results remains ambiguous, since the average continental crust and paragneisses of the Silvretta also show VA-type signatures in the respective diagrams. Nd model ages on four Mönchalpgneiss whole-rock samples from the type locality are closely grouped around 1.70 Ga, which is a commonly obtained value for European continental crust. This age is interpreted to be the result of a homogeneous mixture of different crustal components.

Abstract An extensively exsolved cummingtonite from central Massachusetts, studied by transmission electron microscopy (TEM), contains nm-scale discs of hornblende which represent the youngest exsolution event. Because of the small size of these lamellae, it is only possible to obtain qualitative energy dispersive X-ray (EDX) analyses on a standard analytical TEM. An alternative new method to verify the presence of nm-scale exsolutions, called electron spectroscopic imaging (ESI), is described in this paper. By using electrons which have lost energy to Ca atoms (Ca1,2,1,3), ESI clearly distinguishes between the matrix and the disc-shaped lamellae. In contrast to EDX spectroscopy, ESI has the advantage that light elements can also be analysed, and that the electron beam does not have to be focused to reach a spatial resolution of < 2 nm, thus minimizing beam damage to the sample. The potential for quantification using ESI is discussed; for most of the mineralogically important elements (Z < 30) quantitative analyses can be obtained with the same accuracy as with EDX spectroscopy.

Abstract Functional bioceramic calcium phosphate thin films and thick coatings have been applied by a wide range of techniques to load-bearing metallic substrates ofbiomedical implants. In particular, research and development into bioceramic hydroxylapatite (HAp; Ca10(PO4)6(OH)2) coatings applied by plasma spray techniques show that the microstructure, cohesion and adhesion strength, and the in vivo resorption resistance of such coatings can be optimized by selecting appropriate plasma parameters. Since the functionality of a coating system depends to a large extent on the chemical and phase compositions at the substrate/coating interface, proper engineering of its microstructure is of paramount importance for the long-term stability of the bioceramic coating. Dense, highly crystalline, and phase-pure HAp coatings show maximum mechanical and biochemical stability in the very corrosive body environment. As a consequence, the plasma spray parameters and hence the microstructure of the deposited coatings need to be optimized by controlling the heat transfer from the plasma to the particles. In this paper, ways will be pointed out to potentially improve the properties and thus the in vivo performance of plasmasprayed HAp coatings including their adhesion strength and resorption resistance.