Olivine-plagioclase corona textures occur in ophitic to sub-ophitic olivine gabbros at Black Hill, South Australia. Contrasting with many corona and symplectite textures previously described, these do not involve spinel or garnet as reaction products and did not form under high-pressure conditions. Rather, the coronas formed at no more than 1 kbar pressure and are composed of a shell of orthopyroxene around the olivine often succeeded by a shell of amphibole or occasionally biotite. Beyond this, a vermicular symplectite of anorthite containing orthopyroxene and rarer amphibole vermicules extends out to host plagioclase of labradorite composition. Textural relations are used to infer a subsolidus igneous origin for all but the orthopyroxene shell which may have formed in the presence of some magma. Compositional zonation is absent from all the constituent phases except the amphibole shell which is strongly zoned in Mg# and may have a late origin. An average maximum corona width of 150- 200 μm indicates a limiting distance for subsolidus chemical diffusion. The corona products involve the reactants olivine and plagioclase in the proportions 1:3 and symplectite formation may have been promoted by a Na potential gradient. The system must also have been open to minor components including H2O and TiO2, with H2O possibly being derived from a hydrothermal system. Such systems may have been set up in the country rocks on intrusion of the magma and subsequently collapsed inwards into the pluton during sub-solidus cooling.

Takedaite, Ca3B2O6, has been found in crystalline limestone near gehlenite−spurrite skarns at Fuka, Okayama Prefecture. It occurs as aggregates of granular crystals up to 0.8 mm long and 0.3 mm wide. The mineral is associated with nifontovite, olshanskyite, pentahydroborite, frolovite, sibirskite, calcite and an unidentified mineral, is white or pale gray, and has a vitreous luster. Takedaite is trigonal with space group of Rc, a = 8.638(1), c = 11.850(2)Å, Z = 6. The strongest lines in the X-ray powder pattern [d in A(I)(hkl)] are 2.915(100)(113), 1.895(75)(223), 2.756(61)(104), 2.493(44)(300), 2.044(21) (214,131), 2.160(19)(220), 1.976(18)(006), 1.549(12)(306). The Vickers microhardness is 478 kg mm−2 and the Mohs hardness 4.5. The density is 3.10(2) g cm−3 (meas.) and 3.11 g cm−3 (calc.). Wet chemical analyses give the values CaO 71.13%, B2O3 28.41%, ig. loss 0.14%, and total 99.68%. The empirical formula calculated on the basis of O = 6 is Ca3.053B1.965O6, with the simplified formula of Ca3B2O6.

Here we report a nomenclature and classification for the seidozerite-supergroup minerals. The TS (Titanium-Silicate) block is the main structural unit in all seidozerite-supergroup structures; it consists of a central O (O = Octahedral) sheet and two adjacent H (H = Heteropolyhedral) sheets where Si2O7 groups occur in the H sheets. The TS block is characterized by a planar minimal cell based on translation vectors, t1 and t2, the lengths of these vectors are t1 ≈ 5.5 and t2 ≈ 7 Å, and t1 ^ t2 is close to 90°. The forty-five minerals of the sedozerite supergroup are divided into four groups based on the content of Ti and topology and stereochemistry of the TS block: in rinkite, bafertisite, lamprophyllite and murmanite groups, Ti (+ Nb + Zr + Fe3+ +Mg + Mn) = 1, 2, 3 and 4 apfu (atoms per formula unit), respectively. All TS-block structures consist either solely of TS blocks or of two types of block: the TS block and an I (Intermediate) block that comprises atoms between two TS blocks. Usually, the I block consists of alkali and alkaline-earth cations, H2O groups and oxyanions (PO4)3-, (SO4)2- and (CO3)2-.The general formula of the TS block is as follows AP2 BP2 MH2 MO4 (Si2O7)2X4+n, where MH2 and MO4 = cations of the H and O sheets; MH = Ti, Nb, Zr, Y, Mn, Ca + REE, Ca;MO = Ti, Zr, Nb, Fe3+, Fe2+, Mg, Mn, Zn, Ca, Na; AP and BP = cations at the peripheral (P) sites = Na, Ca + REE, Ca, Zn, Ba, Sr, K; X = anions = O, OH, F, H2O; XO4+n=XO4 +XPn , n = 0, 1, 1.5, 2, 4; XP = XPM and XPA = apical anions of MH and AP cations at the periphery of the TS block.

Twenty-six compositions in the system MgO-Al2O3-SiO2-H2O were investigated under conditions of 1 and 2 Kb water pressure and temperatures between 300 and 700°C. The solid solution for 7 Å and 14 Å chlorites has been delimited as well as that of the expanding phases (tri- and dioctahedral montmorillonites and expanding chlorites). Negative slopes were found for the transformation montmorillonite → expanding chlorite, and expanding chlorite → chlorite+quartz and a positive slope for 7Å → 4 Å transformation. The relative positions of the reactions chlorite+quartz → cordierite+talc, chlorite+andalusite → cordierite and chlorite+corundum → cordierite+spinel are located between 500 and 65°C.

Cell dimensions of the synthetic chlorites can be correlated with their chemical composition. Solid solution in synthetic minerals compares well with 325 analysis of natural minerals from the literature, indicating that the chemiographic relations between phases in the simplified synthetic system are applicable to natural mineral assemblages. The phase relations indicate that at low temperature the 7Å aluminous chlorite is not stable with quartz or another silica phase.

The amphibolites and mafic schists that occur in the Precambrian metamorphic rocks of the Grand Canyon are divided into five major groups: anthophyllite and cordierite-anthophyllite rocks, early amphibolites, Granite Park mafic complex, hornblende-beating dykes, and tremolite-bearing dykes. Many types of amphibole occur in these rocks. Microprobe analyses identify gedrite, anthophyllite, cummingtonite, and grunerite, as well as three groups of calcic amphiboles. These last range in composition from colourless tremo-litic or actinolitic amphiboles, through pale-green horn-blende, to strongly pleochroic green-brown hornblende, which contains a significant proportion of the tscherma-kite and pargasite endmembers. Phase relationships between the coexisting amphiboles and other minerals are presented for two regional metamorphic events. Assem-blages containing chlorite, garnet, and hornblende were formed during the first event; from the absence of staurolite, but the presence of almandine garnet and oligoclase-andesine, it is concluded that the metamorphic grade was between the upper greenschist and the lower amphibolite facies. The second period of metamorphism produced rocks of the staurolite and sillimanite zones, within which three main ‘subfacies’ can be distinguished on the basis of phase relationships in the mafic schists.

The structure hierarchy hypothesis states that structures may be ordered hierarchically according to the polymerization of coordination polyhedra of higher bond valence. A mathematical hierarchy is an ordered set of elements where the ordering reflects a natural hierarchical relation between (or arrangement of) the elements. Here, I review the structure hierarchies for the borate, uranyl oxide, phosphate, sulfate, beryllate and oxide-centred Cu, Pb and Hg minerals (plus synthetics where appropriate). Structure hierarchies have two functions: (1) they serve to organize our knowledge of minerals (crystal structures) in a coherent manner; (2) if the basis of the classification involves factors that are related to the mechanistic details of the stability and behaviour of minerals, then the physical, chemical and paragenetic characteristics of minerals should arise as natural consequences of their crystal structures and the interaction of those structures with the environment in which they occur. We may justify the structure hierarchy hypothesis by considering a hypothetical structure-building process whereby higher bond-valence polyhedra polymerize to form the structural unit. The clusters constituting the FBBs (fundamental building blocks) may polymerize to form the following types of structural unit: (1) isolated polyhedra; (2) clusters; (3) chains and ribbons; (4) sheets; and (5) frameworks. The major advantage of this approach to structure hierarchy is the fact that the hypothetical structure-building process outlined above resembles (our ideas of) crystallization from an aqueous solution, whereby complexes in aqueous and hydrothermal solutions condense to form crystal structures, or fragments of linked polyhedra in a magma condense to form a crystal. Although our knowledge of these processes is rather vague from a mechanistic perspective, the foundations of the structure hypothesis give us a framework within which to think about the processes of crystallization and dissolution.

Arsenic and fluoride in groundwater from Quaternary loess deposits in Argentina pose major health concerns. Common sources for arsenic and fluoride have been suggested but the processes of mobilization are disputed, and distributions in groundwater are largely unresolved at a sample density >1/50 km2. At Los Pereyras in Tucumán Province, northern Argentina, we have evaluated distributions and hydrochemical associations of arsenic and fluoride with a sample density of 0.75 per km2 over an area of 75 km2, to a depth of 230 m. Groundwater in the loess is oxic and alkaline. Fluoride is restricted to the upper 20 m of the Quaternary loess, where it reaches 8.3 mg/1. Arsenic has a vertical layering consistent with that of fluoride, ranging from 20 to 760 μg/1 in the upper 20 m and 58—163 μg/l below this. There are two sources of arsenic, one unrelated to the fluoride source. Positive correlations between arsenic and fluoride with pH, but not with alkalinity, support desorption from iron oxyhydroxides as the likely mechanism of release to groundwater for arsenic and fluoride, rather than the weathering of silicate minerals. Stratigraphic and/or palaeohydrological controls may explain the observed depth distributions within the loess aquifer.

The petrographical, crystal-chemical and petrogenetical aspects of rutile rich in antimony (up to 33.75 wt.% Sb2O5; equal to 0.2 Sb5+ per O = 2) from St. Marcel-Praborna in the Aosta Valley, Italy, were re-examined. These compositions occur in two different petrographical environments (within the rock matrix or as microinclusions within Sb-rich titanite) in the manganese concentrations at this locality. The new data confirm our earlier hypothesis that two distinct petrogenetical/crystal-chemical processes both occurred: 1. Sb-metasomatism of pre-existing Sb-free rutile inclusions; and 2. creation of neoblastic Sb-rich rutile by the expulsion of Ti from pre-existing Sb-free titanite being metasomatized by Sb to form Sb-rich titanite. In the literature, Sb in minerals is variably considered as being trivalent and/or pentavalent. This work demonstrates that within rutile it is entirely Sb5+, substituting for Ti4+ by the following heterovalent cation exchange mechanism which is also the dominant one in the host Sb-rich titanite: 2 viR4+ = viR3+ + viR5+, where viR3+ = (Al,Cr,Mn,Fe)3+. A near-perfect correlation of ΣR5+vs. ΣR3+ (r > 0.98) is perturbed only by the presence of trace amounts of Ca2+, Sr2+ and Ba2+. Traces of Mn4+, Si4+ and/or (OH)− might also be present. These alkaline earth cations are the largest cations ever recorded in the rutile structure and are seemingly too large to occupy normal octahedral sites. The cation exchange mechanism involved might be that found in the ‘trirutile’ mineral group: 3 viR4+ = viR2+ + 2 viR5+. Alternatively these large divalent cations may be situated in the lozenge-shaped tunnels of the rutile structure, by analogy with other large cations occupying the wider subrectangular tunnels in the analogous cryptomelane/hollandite/priderite, romanéchite and todorokite mineral groups. This leads to a possible new cation exchange mechanism for the rutile structure: 2 viR4+ + tunelvacant = 2 viR3+ + tunnelR2+.

A series of titanium silicate glasses along the composition joins TiO2-SiO2, TiO2-Na2SiO3, TiO2-K2SiO3 and TiO2-CaSiO3, has been examined using oxygen K-edge X-ray absorption near edge structure spectroscopy (XANES) confined to the near-surface region. Sharp pre-edge features in the spectra can be used to determine the Ti coordination in the glasses. The presence of [4]Ti is indicated by a pre-edge peak at ∼534 eV while [5]Ti is indicated by a peak at ∼533 eV. Titanium exists in all these glasses as [4]Ti and [5]Ti with no [6]Ti being present. For alkali-containing glasses the [5]Ti site becomes more prevalent with increasing TiO2. TiO2-K2SiO3 compositions contain a greater proportion of [4]Ti than comparable Na2O compositions. This is consistent with earlier Ti L-edge findings. The TEY spectra for the TiO2-CaSiO3 compositions indicate the presence of significant amounts of [5]Ti at high TiO2 contents; however, comparison of TEY (near surface) and FY (bulk sample) XANES shows that the [5]Ti is confined to the surface of the glass sample with the bulk of the glass containing [4]Ti.

The compositions of trioctahedral micas from 51 samples of granitoids with different geochemical affiliations and grades of differentiation from the Bohemian Massif, Central Europe, were analysed using electron microprobe (major elements) and laser ablation inductively coupled plasma mass spectrometry (Li, Sc, Ga, Ge, Nb, In, Sn, Cs, Ta, W, Tl). The micas form a continuous evolutionary series from phlogopite to zinnwaldite. The phlogopites and biotites from the I-type rocks are characterized by 5.5–5.7 Si, 2.4–2.6 Al, <0.1 Li atoms per formula unit [apfu] and Mg/(Mg + Fe) = 0.4–0.8. The biotites from the S-type granites usually contain 5.3–5.7 Si, 3.2–3.6 Al, 0.1–0.3 Li apfu and Mg/(Mg + Fe) = 0.15–0.4. The annites and zinnwaldites from the rare-metal granites contain 5.7–6.8 Si, 3.2–3.8 Al, 0.6–2.6 Li apfu and Mg/(Mg + Fe) < 0.1. The concentrations of F, Rb, Cs and Tl increase from the phlogopites and biotites to zinnwaldites: F 0.1 → 8 wt.%, Rb2O 0.05 → 1.7 wt.%, Tl 2 → 50 ppm and Cs 40 → 2000 ppm. The concentrations of Sn, Nb, Ta and W in phlogopites and biotites from the I- and S-type granitoids generally correlate with those of the parent rocks and reach values of (in ppm) 20–100 Sn, 20–250 Nb, 1–20 Ta and <5 W. The highest concentrations were found in the Li-annites in the relatively early facies of rare-metal granites (in ppm): 250–600 Sn, 400–600 Nb, 60–120 Ta and 50– 120 W. The zinnwaldites in the late rare-metal granites facies are impoverished in these elements, which is explained by contemporaneous crystallization of cassiterite and columbite. Lithium enters the crystal lattice of trioctahedral micas via the exchange vector Li3□Si3Fe–6Al–1 up to concentrations of ∼2.5 wt.% Li2O (1.5 apfu Li). At higher Li concentrations, Li is incorporated through the exchange vector Li3Si1□–1 Fe–2Al–1.

Two clay samples originating in the kaolinized granite area near St. Austell, Cornwall, have been examined by Mössbauer spectroscopy. The iron-containing impurity in the sample with a red discoloration (sample A) has, by measurement of the hyperfine magnetic field, been identified as hematite. In the case of sample B, which was yellow in colour, preliminary Mössbauer work indicated β-FeOOH as the impurity, but detailed measurements of hyperfine field and Nöel temperature, when compared with similar results for a synthetic β-FeOOH sample, suggested otherwise. X-ray and chemical work suggested that the iron-containing phase in sample B is goethite, α-FeOOH in which some substitution of Al+3 for Fe3+ has occurred; the Mössbauer data are consistent with this conclusion. Both clay samples exhibited superparamagnetic behaviour and this has been utilized to obtain rough estimates of the mean radius of the particles of the iron-containing impurity. These were 117 Å for the α-Fe2O3 in sample A and 270 Å for aluminian α-FeOOH in sample B.

Composite populations of monazite-group minerals of both metamorphic and metasomatic origin have been discovered in thin layers of granulite-facies metabasites interlayered with metapelites, located in the Val Strona di Omegna region of the Ivrea-Verbano Zone, Italy. In addition to monazite-(Ce), which is uncommonly poor in Th and is probably formed by incongruent dissolution of apatite, these populations include members of the monazite-huttonite series. The latter minerals contain between 13 and 30.1 mol.% ThSiO4 [= huttonitic monazite-(Ce)], and are known from only half a dozen other occurrences worldwide. We propose that breakdown of primary monazite-(Ce) in the metapelites during granulite-facies metamorphism mobilized Th and the REEs, which were then transported by high-grade metamorphic fluids into the metabasite layers to form the Th-rich minerals of the monazite-huttonite series.

Several strategies are available to reduce or eliminate recalcitrant sulfonamide antibiotics (sulfa drugs) from aqueous media. These contaminants are bioactive and ubiquitous pollutants of soils and watercourses and are known to induce bacterial resistance. Here the biological, chemical and physical methods developed over the last 5 years to decontaminate waters polluted with sulfa drugs are reviewed with special attention to procedures that make use of porous adsorbent materials and their applicability to real waters.

Two occurrences of rutile are reported from Big Bell in Western Australia containing up to 5·8 wt % WO3, 1·7 wt % Sb2O5, and 1·7 wt % FeO. One occurs in a mica schist, and the other in a pegmatite, and both contain a fine intergrowth of ilmenite lamellae. Small grains of gudmundite are associated with the rutile in the pegmatite. Microprobe analyses do not conclusively establish the mechanism of isomorphous substitution.

Carbonatites are enriched in critical raw materials such as the rare-earth elements (REE), niobium, fluorspar and phosphate. A better understanding of their fluid regimes will improve our knowledge of how to target and exploit economic deposits. This study shows that multiple fluid phases penetrated the surrounding fenite aureole during carbonatite emplacement at Chilwa Island, Malawi. The first alkaline fluids formed the main fenite assemblage and later microscopic vein networks contain the minerals of potential economic interest such as pyrochlore in high-grade fenite and rare-earth minerals throughout the aureole. Seventeen samples of fenite rock from the metasomatic aureole around the Chilwa Island carbonatite complex were chosen for study. In addition to the main fenite assemblage of feldspar and aegirine ± arfvedsonite, riebeckite and richterite, the fenite contains micro-mineral assemblages including apatite, ilmenite, rutile, magnetite, zircon, rare-earth minerals and pyrochlore in vein networks. Petrography using a scanning electron microscope in energy-dispersive spectroscopy mode showed that the rare-earth minerals (monazite, bastnäsite and parisite) formed later than the fenite feldspar, aegirine and apatite and provide evidence of REE mobility into all grades of fenite. Fenite apatite has a distinct negative Eu anomaly (determined by laser ablation inductively coupled plasma mass spectrometry) that is rare in carbonatite-associated rocks and interpreted as related to pre-crystallization of plagioclase and co-crystallization with K-feldspar in the fenite. The fenite minerals have consistently higher mid REE/light REE ratios (La/Sm ≈ 1.3 monazite, ≈ 1.9 bastnäsite, ≈ 1.2 parisite) than their counterparts in the carbonatites (La/Sm ≈ 2.5 monazite, ≈ 4.2 bastnäsite, ≈ 3.4 parisite). Quartz in the low- and medium-grade fenite hosts fluid inclusions, typically a few micrometres in diameter, secondary and extremely heterogeneous. Single phase, 2- and 3-phase, single solid and multi solid-bearing examples are present, with 2-phase the most abundant. Calcite, nahcolite, burbankite and baryte were found in the inclusions. Decrepitation of inclusions occurred at ∼200°C before homogenization but melting-temperature data indicate that the inclusions contain relatively pure CO2. A minimum salinity of ∼24 wt.% NaCl equivalent was determined. Among the trace elements in whole-rock analyses, enrichment in Ba, Mo, Nb, Pb, Sr, Th and Y and depletion in Co, Hf and V are common to carbonatite and fenite but enrichment in carbonatitic type elements (Ba, Nb, Sr, Th, Yand REE) generally increases towards the inner parts of the aureole. A schematic model contains multiple fluid events, related to first and second boiling of the magma, accompanying intrusion of the carbonatites at Chilwa Island, each contributing to the mineralogy and chemistry of the fenite. The presence of distinct rare-earth mineral microassemblages in fenite at some distance from carbonatite could be developed as an exploration indicator of REE enrichment.

Zeolites occur at most of the 670 localities studied in the Antrim Basalts, and the ten most abundant species, in order of frequency, are chabazite, thomsonite, analcime, levyne, natrolite, mesolite, stilbite, gmelinite, heulandite, and phillipsite. Gismondine, laumontite, and mordenite are recorded for the first time. Chabazite and thomsonite characterize the upper parts of the lava succession. Below, they are joined by analcime and natrolite and, in some areas where zeolitization is most intense, by stilbite and heulandite, as well. These mineral zones have been mapped, and they probably reflect the temperature distribution in the lavas during zeolitization. Being discordant and clearly superimposed upon the lavas, these zones establish the late age of zeolitization in the volcanic history of Antrim. In places the zeolite zones are missing, and in their place a mineral assemblage rich in calcite, aragonite, quartz, and chalcedony is found. The tholeiite lavas that occupy a small area in north Antrim have an amygdale mineral assemblage different from that in the olivine-basalts, which constitute the remainder of the lava outcrop.

The volume proportions of the mineral phases in two strongly deformed olivine-orthopyroxene rocks have been quantified by whole-pattern stripping of fixed geometry X-ray powder diffraction data. The results were compared with the phase proportions as determined by Rietveld refinement of time-of-flight neutron powder diffraction data, and were shown to be in excellent agreement. The X-ray technique not only provides a very rapid and cost-effective method of determining phase proportions, but it also circumvents several of the problems associated with obtaining this information by image analysis. Moreover, the technique is particularly advantageous in strongly textured rocks or in rocks that contain significant residual strains. As such it offers a powerful technique for analysing the mineralogical composition of fine-grained and/or deformed experimental run products, which makes it of considerable potential for monitoring in situ the progress of mineral reactions during laboratory experiments.

Magnetite—apatite deposits associated with the Atacama Fault Zone of northern Chile are interpreted here, on field criteria, as being the products either of hydrothermal fluids with a strong magmatic signature, or of late-stage Fe-rich magmas mixed with an aqueous fluid. Even in the Chilean iron belt, apatite-rich magnetite deposits are a rarity. Variations in F- and Cl- contents in apatites, strongly zoned with respect to halogens, are indicative of primary variations in fHF and fHCI in the hydrothermal fluids. Small variations in halogen fugacities in the aqueous fluid are capable of buffering large variations in halogen content within apatite crystals in equilibrium with that fluid. The recorded halogen zonation profiles are inconsistent with crystallization of the apatites simply from a volatile-rich, late-stage fractionation Fe-rich magma, or its derived magmatic vapour. It is more likely that they are the result of mineral—fluid buffering with a fluid that represents the mixing of a magmatically-derived aqueous fluid with a meteoric fluid that has variably scavenged Ca and Cl from within the country rocks. The source magma of the former is probably an Fe-P enriched acidic magma, derived by fractionation of primary calc-alkaline basic magmas.

The crystal structure of quintinite-2H-3c, [Mg4Al2(OH)12](CO3)(H2O)3, from the Kovdor alkaline massif, Kola peninsula, Russia, was solved by direct methods and refined to an agreement index (R1) of 0.055 for 484 unique reflections with |Fo| ≥ 4σF. The mineral is rhombohedral, R32, a = 5.2745(7), c = 45.36(1) Å. The diffraction pattern of the crystal has strong and sharp Bragg reflections having h–k = 3n and l = 3n and lines of weak superstructure reflections extended parallel to c* and centred at h–k ≠ 3n. The structure contains six layers within the unit cell with the layer stacking sequence of …AC=CA=AC=CA=AC=CA… The Mg and Al atoms are ordered in metal hydroxide layers to form a honeycomb superstructure. The full superstructure is formed by the combination of two-layer stacking sequence and Mg-Al ordering. This is the first time that a long-range superstructure in carbonate-bearing layered double hydroxide (LDH) has been observed. Taking into account Mg-Al ordering, the unique layer sequence can be written as …=Ab1C=Cb1A=Ab2C=Cb2A=Ab3C=Cb3A=… The use of an additional suffix is proposed in order to distinguish between LDH polytypes having the same general stacking sequence but with different c parameters compared with the ‘standard’ polytype. According to this notation, the quintinite studied here can be described as quintinite-2H-3c or quintinite-2H-3c[6R], indicating the real symmetry.