Staringite, (Fe,Mn)0·5(Sn,Ti)4·5(Ta,Nb)1·0O12, occurs as inclusions in tapiolite from pegmatites at Seridózinho and Pedra Lavreda, Paraiba State, NE. Brazil. An indexed powder pattern is presented. The mineral is tetragonal with a 4·742 Å and c 9·535 Å, and most probably has a ‘trirutile’ structure. Electron-microprobe analysis yielded Ta2O5 21·5%, Nb2O5 1·8, SnO2 73·3, TiO2 0·03, FeO 3·7, MnO 0·3, sum 100·6%. Dcalc 7·17. Micro-indentation hardness (load 100 g) 1033–1187 kg/mm2; reflectivity at 470 nm (R0) 12·8 to (R′e) 14·5%, at 546 nm 12·1–13·9, at 589 nm 12·0–13·7, and at 650 nm 11·8–13·6; staringite is uniaxial positive.

Geochemical investigation of samples from 20 granitic intrusions in six tectonic zones of the Hellenides shows that both I-type and S-type granites occur in the region. The I-type granites from four of the zones, namely the Rhodope Massif (RM), the Serbomacedonian Massif (SMM), the Perirhodope Zone (PRZ) and the Attico-cycladic Zone (ACZ), show some systematic differences in their geochemistry. In particular, the Rb, Y, Nb, K and Ti contents increase in the sequence PRZ, SMM, RM and ACZ. The PRZ granites are of Jurassic age, those of the SMM and RM are Eocene to Oligocene and the ACZ ones are Miocene. The differences between zones are attributed to a combination of differences in partial melting and high-pressure fractionation processes. Geochemical differences within zones are explained by variable degrees of amphibole and apatite fractionation and accumulation.

Coal slag and ash, obtained from burning coal in a textile factory in Duga Resa (Croatia) was discharged directly into the Mrežnica River for 110 y (1884–1994), from where it travelled to the Korana River and further to the Kupa River at Karlovac, a total of ~50km from its source. Of 54 elements determined by inductively coupled plasma mass spectrometry (ICP-MS) in the <2 mm sediment fraction, a number of anomalously high levels were recorded. The geoaccumulation index (Igeo) for the anomalous elements were: Hg (1.88), B (4.05), Na (1.44), Al (2.05), V (1.65), Cr (1.20), Fe (1.18), Ni (2.10), Cu (2.37), Sr (0.97), Zr (3.27), Mo (3.34) and U (4.03). Low-field magnetic susceptibility (MS) was measured for each sample. The Igeo for MS in the anomalous region is 5.85. Correlation analysis showed good correlation (>0.90) of MS with: B (0.96), U (0.95), Zr (0.94), Sr (0.93), Na (0.92), Mo (0.92) and Ni (0.90). Cluster analysis of R-modality indicates that MS is linked to B, Mo, Na and U. Low correlation of MS with Fe (0.36) suggests that Fe in stream sediments is not in a ferromagnetic form. Neither maghemite, nor magnetite phases were identified by X-ray diffraction (XRD) in the sediments. Low-field magnetic susceptibility provides an indicator of contamination of river sediments by transported coal slag and ash, although it cannot be prescribed to a single element.

Two new analyses of magnesian cordierites (MgO ∼ 12 %) reveal about 1% by weight of H2O +, and one sample contains 15 × 10−5 cm3STP/gm argon, which is twenty times in excess of argon expected for its age. Host granulites contain unexpectedly light oxygen, and three cordierites have δ 18O values of 2·0, 2·8, and 3·1 ‰, respectively.

The determination of ferrous iron in minerals, such as staurolite and kornerupine, which cannot be effectively dissolved by dilute sulphuric and hydrofluoric acids has been made possible on the macro-scale by the work of H. P. Rowledge; the mineral is fused with sodium fluoride and boric oxide at 900°C. in a sealed pyrex glass tube, the fusion cake dissolved in hot dilute sulphuric acid in a current of carbondioxide, and the solution titrated with potassium permanganate. We have met with no difficulty in applying the method on the macro-scale, but when only small amounts of a mineral are available several difficulties arise, and modifications become necessary.

The air present in the sealed tube of a Rowledge fusion, using the quantities and dimensions he specifies, is already sufficient to oxidize about 3 to 5 mg. of ferrous oxide. But when the weight of the sample is reduced to 10 mg., it is not possible to reduce the dead-space in the tube in proportion ; it can hardly be reduced below about ¼c .c. which is sufficient to oxidize 0·3 mg. or 3% FeO and is likely to be more effective in this direction than on the larger scale, since the surface of the fusion is proportionally greater.

Two small fragments of unpromising-looking ferruginous material, recovered from inside the Dalgaranga crater, near Mount Magnet, Western Australia, have been sectioned and, while one is largely composed of iron oxides and adds little to the record of this crater, the second fragment is one of the rare, predominantly stony ones reported by Nininger and Huss, and is sufficiently fresh for a thin section to be prepared. As far as is known no thin sections have been described of material from this crater. Microscopic study with transmitted light shows the stony material to be achondritic and to have affinities with the mesosiderites, and, in spite of the low nickel-iron content of this fragment, it seems preferable to regard it as representative of an iron-poor area within a mesosiderite than as true stony meteorite material. Although closely related to the howardites it cannot be classified with any known achondrite type because of the prominent olivine phenocrysts and it bears no resemblance at all to chondritic material. Mineralogical and petrographical details are described and illustrated, and the significance of this new evidence discussed. The origin of the crater is reconsidered.

K-rich nepheline with a structural formula of A2B6T14T24T34T44O32 (Z = 1) within melilite–olivine nephelinite from Hamada, Shimane Prefecture, Japan, was investigated to clarify its crystal structure and to determine cation distributions in the A and B structural positions of structural channels and tetrahedral T1–T4 sites. The chemical formula of a single-crystal sample was (Na5.437K2.248Mg0.034Ca0.031)Σ7.750(Si8.332Al7.445Fe3+0.158Ti0.009Cr0.005)Σ15.949O32, which results in 65.2, 27.8, 2.1, 3.2 and 1.6 mol.% NaAlSiO4, KAlSiO4, NaFe3+SiO4, □Si2O4 and □0.5(Ca,Mg)0.5AlSiO4 end-member components, respectively, where □ is a vacancy. X-ray diffraction data of a single crystal with dimensions of 0.28 mm × 0.15 mm × 0.05 mm measured at 296 K indicate the space group P63. In the structural refinement, the R1 factor was reduced to 3.69% by taking twinning by merohedry into the refinement. The refinement accounted for 77.7% of the absolute structure and 22.3% of the a and b axes reversed absolute structure. The atomic populations determined in the A and B positions were 1.834 K + 0.166 □ and 5.705 Na + 0.198 K + 0.031 Ca + 0.034 Mg, respectively, implying the substitution of K for Na in the B position. The a and c dimensions are a = 10.0270(3) and c = 8.4027(3) Å. The average <A–O> and <B–O> distances are 3.009 and 2.65 Å, respectively. The substitution of K for Na in the B channel results in increased volume and bond-length distortion of the BO8 polyhedra, which then reduces distortion of the AO9 polyhedra. The average T–O distances indicate that the T1 and T4 sites are essentially filled with Al, whereas the T2 and T3 are filled with Si. Despite the deviation of the O1 oxygen from the triad axis and the combination of K+ ions and vacancies in the hexagonal channels, an incommensurate structure was not observed in the X-ray diffraction data or using the electron diffraction technique.

The new mineral zubkovaite, Ca3Cu3(AsO4)4, was found in the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with anhydrite, svabite, hematite, johillerite, tilasite, fluorophlogopite, sanidine and aphthitalite. Zubkovaite occurs as coarse prismatic crystals up to 0.01 mm × 0.01 mm × 0.2 mm combined in radiating aggregates or crusts. The mineral is transparent, bright sky-blue, turquoise-coloured or light bluish-green, with vitreous lustre. It is brittle, with imperfect cleavage. The Mohs’ hardness is ca 3. Dcalc is 4.161 g cm–3. Zubkovaite is optically biaxial (–), α = 1.747(5), β = 1.774(5), γ = 1.792(5) and 2Vmeas = 75(10)°. Chemical composition (wt.%, electron microprobe) is: CaO 19.22, CuO 27.37, As2O5 52.54, SO3 0.67, total 99.80. The empirical formula based on 16 O apfu is Ca2.96Cu2.97(As3.945S0.07)Σ4.015O16. Zubkovaite is monoclinic, C2, a = 16.836(3), b = 5.0405(8), c = 9.1173(17) Å, β = 117.388(13)°, V = 687.0(2) Å3 and Z = 2. The strongest reflections of the powder XRD pattern [d,Å (I) (hkl)] are: 7.44 (100) ($\bar 2$01), 3.727 (79) (400, $\bar 2$02, $\bar 3$11), 3.334 (92) ($\bar 1$12), 2.914 (73) (311), 2.765 (50) ($\bar 6$01, $\bar 6$02), 2.591 (96) ($\bar 3$13) and 2.521 (53) (020). The crystal structure is unique for minerals. It was solved from single-crystal X-ray diffraction data to R = 7.19%. The structure contains trimers of Cu2+-centred polyhedra (consisting of one distorted square CuO4 in the core and two distorted square pyramids CuO5) and two crystallographically independent As5+O4 tetrahedra playing different roles: As(2)O4 tetrahedra link neighbouring trimers into ribbons whereas As(1)O4 tetrahedra link adjacent ribbons into heteropolyhedral layers; Ca cations are located in the interlayer space. The mineral is named in honour of the Russian crystallographer and crystal chemist Natalia Vital'evna Zubkova (born 1976).

We have investigated the chemical zoning of garnet in three texturally different eclogite types from the Leaota Massif, Romania, to test the various zonation patterns of Ca, Fe, Mg and Mn as indices of time-lines in porphyroblastic garnets. Mn zonation was found to mark various growth stages very well. It indicates in each of our three case studies a complex growth history dominated by multiple nucleation and coalescence, but also interrupted by partial resorption, as shown by morphological characteristics. Chemical variations of the main elements in garnet during prograde high-pressure metamorphism define time-lines other than those of Mn which decrease, highlighting the stages of porphyroblastic growth. In particular, the Ca/Mn, Mg/Mn and Mg/Fe ratios are useful in late growth stages, when low Mn contents and radial gradients do not allow a satisfactory resolution of Mn time-lines. These ratio-based time-lines further substantiate the potential of Mn time-lines in revealing non-concentric porphyroblastic growth. This is important in order to correctly relate garnet growth stages to stable mineral assemblages, a prerequisite for a reliable derivation of the metamorphic history of the host rock.

Turkestanite, a rare Th- and REE-bearing cyclosilicate in the ekanite–steacyite group was found in evolved peralkaline granitesfrom the Morro Redondo Complex, south Brazil. It occurswith quartz, alkali feldspar and an unnamed Y-bearing silicate. Electron microprobe analysis indicates relatively homogeneous compositions with maximum ThO2, Na2O and K2O contentsof 22.4%, 2.93% and 3.15 wt.%, respectively, and significant REE2O3 abundances(5.21 to 11.04 wt.%). The REE patterns show enrichment of LREE over HREE, a strong negative Eu anomaly and positive Ce anomaly, the latter in the most transformed crystals. Laser ablation inductively coupled plasma mass spectrometry trace element patterns display considerable depletions in Nb, Zr, Hf, Ti and Li relative to whole-rock sample compositions. Observed compositional variations suggest the influence of coupled substitution mechanisms involving steacyite, a Na-dominant analogue of turkestanite, iraqite, a REE-bearing end-member in the ekanite–steacyite group, ekanite and some theoretical end-members. Turkestanite crystals were interpreted as having precipitated during post-magmatic stages in the presence of residual HFSE-rich fluidscarrying Ca, the circulation of which wasenhanced by deformational events.

The new mineral aluminopyracmonite, ideally (NH4)3Al(SO4)3, was found in a medium-temperature (∼250°C) intracrater active fumarole at La Fossa crater, Vulcano, Aeolian Islands, Sicily, Italy. It occurs on a pyroclastic breccia as colourless to white prismatic crystals up to 0.2 mm long, in association with adranosite, mascagnite, alunite and salammoniac. The mineral is identical to the synthetic compound (NH4)3Al(SO4)3. It is trigonal, space group: R (no. 148) with a = 15.0324(8), c = 8.8776(5) 5, V = 1737.3(2) Å3 and Z = 6. The six strongest reflections in the X-ray powder diffraction pattern are: [dobs in Å (I)(hkl)] 3.336(100)(131), 7.469(62)(1 1 0), 3.288(60)(122), 4.289(45)(31), 2.824(29)(51), 4.187(27) (012). The empirical formula based on 12 anions is [(NH4)2.89K0.10]Σ 2.99(Al1.18Fe0.01)Σ 1.19S2.91O12, and the simplified formula (NH4,K)3Al(SO4)3. The measured density is 2.12(1) g/cm3, calculated density 2.143 g/cm3. The mineral is uniaxial(–) with ω = 1.545(3) and ε = 1.532(3) (λ = 589 nm). Using single-crystal diffraction data, the structure was refined to a final R(F) = 0.0258 for 998 independent observed reflections [I > 2σ(I)]. In spite of having unitcell parameters comparable with those of pyracmonite, the two minerals are not isostructural; the difference is related to a disordered conformation of the sulfate anions about the two independent Al3+ ions in aluminopyracmonite.

Several quartzite bodies outcrop along the Ferreira-Ficalho Thrust Fault (South Portugal), a major accident of the Iberian Variscan Orogen. The sediment is a very pure quartz sandstone, with trace amounts of ultra-resistant heavy minerals and chromite. Chemical characterization (microprobe analyses and Mössbauer spectroscopy) showed the chromite to be unique: besides being Zn-rich, complexly zoned and a cation deficient spinel, all the iron was found to be fully oxidized to Fe3+. Structure refinement of single-crystal X-ray diffraction intensities unambiguously identifies the mineral as a chromite and the Mössbauer data are consistent with tetrahedrally coordinated Fe3+ in the spinel structure. Current geodynamical models see the Ferreira-Ficalho Thrust Fault as a first-order suture resulting from a complex collision of two distinct continental blocks with partial obduction of the intervening oceanic crust. The chromite grains could be envisaged as remnants of an early erosion of this obducted oceanic crust, but its unique chemical character does not allow any definite conclusion. Yet, the complete quartzite heavy mineral contents and its petrographic features are not consistent with their deposition within a continental collision situation.

We have investigated a diamond crystal that consists of several misorientated subgrains. The main feature of the crystal is the dark areas in the cathodoluminescent core that has ‘estuary-like’ boundaries extending along the subgrain interfaces. The core has >3100 ppm of nitrogen, and the share of the B form is >95%; the absorbance of the centre N3VH at 3107 cm–1 reaches 75 cm–1. The N3 centre absorbance, as well as N3 luminescence, is absent in the core. In the outer part of the crystal, bright blue luminescence of the N3 centre is apparent, and the N3 absorbance reaches 5.3 cm–1. These observations could be explained by the conversion of N3 centres to N3VH after attaching a hydrogen atom. After the full conversion of the N3 centres, the diamond becomes darker under CL. We hypothesise the dark core has a specific shape due to the post-growth diffusion of the hydrogen.

Allanite is a common accessory mineral in igneous rocks. Allanite becomes metamict over geological time-scales as a result of the α-decay of radioactive elements in the crystal structure. This study focuses on the recrystallization of metamict allanite from Savvushka, Russia. The structural recovery produced by annealing was investigated by X-ray powder diffraction, single-crystal synchrotron X-ray diffraction and infrared spectroscopy. A kinetic analysis is presented that shows that the recrystallization process proceeds by at least two different mechanisms.

An experimental study of optical anomalies in solid solutions of alums in relation to their composition, growth temperatures and rates, and hydrodynamic regime was carried out. Theoretical analysis of the data showed that they can be understood in terms of a mechanism of kinetic ordering of the isomorphous atoms (the phenomenon of so-called ‘growth dissymmetrization’). A theoretical model is presented which is supported by data for a number of minerals and synthetic compounds, which are known for their optical anomalies due to growth dissymmetrization.

A new mineral majzlanite, ideally K2Na(ZnNa)Ca(SO4)4, was found in high-temperature exhalative mineral assemblages in the Yadovitaya fumarole, Second scoria cone of the Great Tolbachik Fissure Eruption (1975–1976), Tolbachik volcano, Kamchatka Peninsula, Russia. Majzlanite is associated closely with langbeinite and K-bearing thénardite. Majzlanite is grey with a bluish tint, has a white streak and vitreous lustre. The mineral is soluble in warm water. Majzlanite is monoclinic, C2/c, a = 16.007(2), b = 9.5239(11), c = 9.1182(10) Å, β = 94.828(7)°, V = 1385.2(3) Å3 and Z = 16. The eight strongest lines of the X-ray powder diffraction pattern are [d, Å (I, %)(hkl)]: 3.3721(40)($\bar{3}$12), 3.1473(56)($\bar{4}$02), 3.1062(65)($\bar{2}$22), 2.9495(50)($\bar{1}$31), 2.8736(100)($\bar{1}$13), 2.8350(70)(421), 2.8031(45)(511) and 2.6162(41)($\bar{5}$12). The following structural formula was obtained: K2Na(Zn0.88Na0.60Cu0.36Mg0.16)(Ca0.76Na0.24)(S0.98Al0.015Si0.005O4)4. The chemical composition determined by electron-microprobe analysis is (wt.%): Na2O 9.73, K2O 15.27, ZnO 11.20, CaO 7.03, CuO 4.26, MgO 1.07, Al2O3 0.47, SO3 51.34, SiO2 0.12, total 100.49. The empirical formula calculated on the basis of 16 O apfu is K1.99Na1.93Zn0.84Ca0.77Cu0.33Mg0.16(S3.94Al0.06Si0.01)O16 and the simplified formula is K2Na(Zn,Na,Cu,Mg)Σ2(Ca,Na)(SO4)4. No natural or synthetic compounds directly chemically and/or structurally related to majzlanite are known to date. The topology of the heteropolyhedral framework in majzlanite is complex. An interesting feature of the structure of majzlanite is an edge-sharing of ZnO6 octahedra with SO4 tetrahedra.

Fibrolitic sillimanite in some high-grade gneisses from Broken Hill, Australia, shows microstructural features suggestive of compatibility with the main coarser-grained assemblage, namely: framework-silicate interfaces either meet (110)-sillimanite/framework-silicate interfaces at approximately 90° or are attached to the ends of 'fibrolite' rods; framework-silicate interfaces are deflected by 'fibrolite' grains; and interfaces of inclusions of one framework silicate in another are deflected by 'fibrolite' grains, producing irregular, rather than rounded, inclusion shapes. These criteria suggest that the 'fibrolite' in some rocks is a compatible member of the main metamorphic assemblage. Its persistence as small grains may be due to a high proportion of relatively low-energy prismatic boundaries in the fibrolitic aggregates.