Four distinct textures and related compositions of kosmochlor (Ko) and chromian jadeite in rocks from the Myanmar jadeitite area are described: (1) spheroidal or ellipsoidal aggregates with a corona texture surrounding relict chromite; (2) spheroidal or ellipsoidal aggregates with a core of jadeite; (3) granoblastic textures in undeformed coarse-grained clinopyroxene rocks; and (4) recrystallized fine-grained aggregates in deformed jadeitite. Nearly pure kosmochlor (97 mol.% NaCrSi2O6) was found in type 2 textures, closest to the end-member reported so far from a terrestrial rock. Sharp compositional boundaries between kosmochlor and chromian jadeite of variable composition are interpreted to be related to progressive crystallization or replacement at differing conditions. The compositions analysed plot along the kosmochlor-jadeite join. In contrast to conclusions of previous studies on the Myanmar clinopyroxenes there is no unequivocal evidence for miscibility gaps. The preservation of relict chromite in the centre of coronitic spheroidal or ellipsoidal aggregates of kosmochlor and jadeite indicates a metasomatic origin from a peridotite protolith at an inferred minimum pressure of 1.0 GPa and temperatures of 250—370°C. Recrystallization during later ductile deformation of the clinopyroxene rocks in the dislocation creep regime leads to fine-grained aggregates of chromian jadeite, which are of particular gemmological interest.

The kinetics of hydrogen mobility in grossular with a chemically homogeneous composition of Gr83.2 And14.3 Py2.2 were studied by sequential annealing experiments monitored by Fourier transform infrared spectroscopy. Slices of single crystals <0.5 mm thick were annealed at temperatures in the range 1073–1323 K at ambient pressure in air and in gas mixtures of Ar(90%)/D2(10%) and Ar(90%)/H2(10%). The change of total infrared (IR) absorbance in the OH-stretching region (3700–3500 cm–1) and the OD-stretching region (2750–2580 cm–1) was used to calculate the diffusion coefficients. The law for diffusion of deuterium is given by D = D0 exp[–102±45 kJ mol–1/ RT] with log D0 (m2/s) = –7.6. For hydrogen extraction in air the diffusion law is expressed by D = D0 exp[–323±46 kJ mol–1/RT] with log D0 (m2/s) = 1.0. This activation energy agrees with the values found for Dora Maira pyrope and for other pyropes from mantle xenoliths, but the diffusivity is slower for the grossular. A detailed investigation of the decrease in individual OH bands during hydrogen extraction in air revealed two different kinds of kinetics behaviour, suggesting that at least two different types of OH defects are present in this grossular.

Ferrihydrite and goethite are amongst the most important substrates for the sorption of contaminants in soil and other environmental media. Isotopic studies of the transition elements, particularly those that exhibit more than one oxidation state and show pH- and/or redox-sensitive behaviour at low temperatures, have been shown to be potentially useful present-day and past proxies for redox (or palaeoredox) conditions. We have made preliminary investigations of Fe isotope fractionation that take place during the formation of FeIII (oxy)hydroxides (FeIIIox) from an aqueous FeIII(NO3)3 solution (FeIIIaq) under laboratory conditions. We have attempted to keep the chemical system simple by excluding 'vital effects' and major changes in redox through the maintenance of abiotic conditions and use of FeIIIaq. Isotopic measurements (56Fe/54Fe, 57Fe/54Fe) of the FeIII(NO3)3 stock solution, the original ferrihydrite and the mixed ferrihydrite/goethite-supernatant FeIIIaq 'pairs' were carried out using a double focusing multicollector inductively coupled plasma mass spectrometer. The results reveal an apparent systematic variation indicating larger ΔFeIIIaq—FeIIIox with decrease in the ferrihydrite:goethite ratio, which reflects the time allowed for isotopic exchange. These values range from virtually zero (0.03%) after 24 h to 0.30% after 70 h. In each FeIIIox-FeIIIaq 'pair' the lighter Fe isotope is partitioned into the FeIIIox, leaving the FeIIIaq isotopically heavier. The observed fractionation reflects isotopic exchange of Fe between the FeIIIox and FeIIIaq upon at least a two step transition of ferrihydrite to goethite.

Fuel-oil contamination of groundwater and waterways is common throughout the world. The fuel components methyl-tert-butyl ether (MTBE) and benzene, toluene, ethylbenzene and o-, p- and m-xylenes (BTEX) compounds are most likely to reach a borehole after a contamination event, and also those that pose the greatest risk.

Various gas chromatography-mass spectrometry (GCMS) methods are available for the analysis of volatile organic compounds (VOCs) but many of these are not suitable for rapid and combined analysis of MTBE and BTEX. Here we describe and validate a simple and reliable method that fulfils these requirements. The method is quick: 48 samples can be analysed in a 24 hour period using the Precept II® autosampler and therefore is suitable for high throughput work. Validation of our experiments is presented in the form of linearity, precision and intra-day repeatability of standards as well as limits of detection and limits of quantification for the range 1—20 μg/l.

This MTBE/BTEX analytical method developed was used to study the optimization of a modular post-abstraction remediation system incorporating air-stripping and granular activated carbon (GAC) technologies (Hall, 2004), from which a selection of sample data is presented.

Intermediate members of the grossular–andradite and grossular–uvarovite series are known to display anomalous birefringence, which is inconsistent with the ideal cubic space group of garnet Iad. To determine the reason for such birefringence, the crystal structures of at least 15 samples were refined by different authors including the present ones. The crystals with the value of anomalous birefringence of Δn > 0.001 are normally characterized by partial ordering of the octahedral cations (Al/Fe and Al/Cr for grossular–andradite and grossular–uvarovite series, respectively). This reduces the symmetry to the orthorhombic space group Fddd or even to the triclinic space group I. As is seen from the distribution of occupancies over octahedral sites in the triclinic space group, eight occupancies are grouped into two quartets of similar occupancies, leading to pseudo-orthorhombic crystal structures. The variety of structures with different degrees of pseudo-orthorhombicity is due to the action of the growth dissymmetrization mechanism. Simulations of the optical indicatrix in the point-dipole approximation confirm cation ordering as the main cause of the anomalous birefringence.

Studies of the weathering of platinum-group minerals in natural deposits have indicated that the platinum-group elements (PGE) can be mobilized under appropriate conditions and have sufficient solubility to move into solution. Although inorganic chemistry provides feasible mechanisms under the extreme conditions encountered in laterites it appears likely that PGE-organic complexes offer a more convincing explanation of the apparent solubility. Experimental work undertaken to illustrate the organic processes and the reaction timescale examined various reactions including those between Pt and Pd foils and humic and fulvic acid solutions. These reactions appear pertinent to those that may occur between the PGE particles ejected by vehicle exhaust catalysts and the natural environment.

The experimental work produced up to 195 μ/l Pt and 102 μ/l Pd in humic acid solutions exposed to the metal foils for about a year at room temperature. The experimental conditions can be compared to those encountered in roadside drainage supplied with PGE particles and decaying vegetation.

Consideration of the possible health effects of the PGE from the particles ejected by vehicle exhaust catalysts has centred on inhalation of the particles or absorption through the skin. Intake from drinking water or from food produced using PGE-bearing water should now also be investigated. Due to the variety of organic compounds produced by decaying vegetation the identity of the PGE-organic products is not yet known so their toxicity cannot be estimated.

The Mathiatis massive sulphide deposit in Cyprus was a low-grade (0.3% Cu), three million ton ore body of pyrite and minor chalcopyrite occurring within basaltic lavas of the Troodos ophiolite. Cessation of mining in 1987 left a deep open pit surrounded by large heaps of spoil, which are undergoing oxidation and leaching. The aim of this study was to determine the mineralogical controls on the storage and potential remobilization of As, Cu, Pb and Zn within, and from, mine spoil heaps. Most of the spoil samples collected, and related materials (stream sediment, reaction zone between a boulder of massive pyrite and calcareous chert, salt crusts on stream beds), are enriched in As (27—220 ppm), Cu (110—400 ppm), Pb (10—140 ppm) and Zn (290—12,000 ppm) relative to both the basalt and calcareous chert (As 4—10 ppm, Cu 20—76 ppm, Pb 3—6 ppm, Zn 39—200 ppm).

Arsenic, Cu, Pb and Zn in the spoil and related materials are associated with Fe(-Al-S)-O, Fe(-Al-Mg)-S-O, Al(-Mg-Fe)-S-O and Mg(-Al-Fe)-S-O phases (the brackets represent minor components of less than 20 wt.% within the phases). Chemical extraction work using CaCl2 suggests that Cu, Zn and to some extent, As, are potentially more soluble than Pb. This is corroborated by the very high total concentrations of Cu and Zn in both the secondary salt crusts and the reaction zone material, high CaCl2-extractable As, Cu and Zn in the salt crusts, and aqueous data for the Mathiatis mine area collected for a European Union LIFE report. This may have implications for ecosystem health and water quality in the Mathiatis area and areas of similar mineralogy and climate world wide.