A blue-green scaly coating on a slaty specimen from the Bastenberg mine, near Ramsbeck, Germany, yielded an X-ray powder pattern akin to schulenbergite. Chemically it is the zinc analogue of schulenbergite. Electron-probe data, XRF and ICP/OES analyses are presented which demonstrate two distinct zinc-rich compositions. Thermogravimetric analysis, together with CHN results, suggest the phase may contain 3-4 water molecules. Powder data are indexed on a hexagonal cell with a 8.293(2) Å, c 7.247(4) Å and cell volume 431.6(2) Å3, with Z = 1.

The crystal chemistry of a meso-octahedral Li,Be-bearing mica from the Harding pegmatite (Dixon, Taos County, New Mexico, USA) has been investigated by constant-wavelength single-crystal neutron diffraction at 20 K, single-crystal X-ray diffraction at 100 K and inductively coupled plasma-atomic emission spectrometry (ICP-AES). The chemical composition based on ICP-AES analysis leads to the following chemical formula (calculated on the basis of 12 oxygen atoms): Ca(Na0.26K0.04Ca0.69)∑0.99M(Li0.29Mg0.03Fe0.023+Al1.78)∑2.12T(Al1.73Be0.16Si2.11)S4.00O12H2.53. The apparent excess of H is probably due to the fact that the fraction of H2O was assumed by difference to 100 wt.%, and slightly overestimated. On the basis of the previous experimental findings on Li,Be-bearing mica, X-ray (at 100 K) and neutron (at 20 K) structure refinements were performed in the space groups Cc and C2/c. The neutron structure refinement in the space group Cc offers a view about the (Al,Be,Si)-tetrahedral ordering: the best fit of the refinement was reached with the T1 and T4 sites occupied by (Be + Al) and T2 and T3 fully occupied by Si. This leads to a final population of T(Al1.88Be0.12Si2.00)∑4.00 p.f.u., in reasonable agreement with the chemical analysis. The neutron refinement provides unambigous evidence of the occurrence of Li at the M1 site. The refined fraction of Li at the M1 site ranges between 0.27 and 0.29 a.p.f.u., in excellent agreement with the chemical analysis. The presence of Li, at least at a significant level, at the M2 (and M3) site can be ruled out, as a full site occupancy with the scattering length of Al was obtained. The location of the H sites and the complex hydrogen-bonding scheme are described. A comparison between the structure features of this Li,Be-mica and other brittle micas is carried out.

Ore specimens from the abandoned copper mine at Seathwaite Tarn, Cumbria, were studied in polished section by reflected light microscopy. The mineral paragenesis is described and related to current views on Lake District ore genesis. A common origin with the neighbouring deposit at Coniston is proposed. Wittichenite was identified in the ore, and is the first authenticated occurrence in Great Britain.

A review is presented here of the crystal chemistry of natural silicates of alkaline elements, mainly Na, with a focus on reporting recent data on the structural mineralogy of the new members of this chemical family and their crystal structures. The majority of the natural hydrous silicates of alkaline elements studied are characterized by a specific crystal-chemical feature − the presence of silanol groups Si−OH. The discovery of the two new minerals, chesnokovite and yegorovite, means that all the main topological types of the [SixOy] complexes are represented in the crystal structures for this family.

Gold of magmatic origin has been discovered in the lamproitic dyke of El Tale (Fortuna, Province of Murcia), a small outcrop of ultrapotassic rocks of tile Tertiary magmatic province of southeastern Spain. It is the first finding of gold grains in lamproite magmas from southeastern Spain, and indeed worldwide. Pure gold occurs only in the glassy groundmass as very rare spherules and globular grains (up to 5 µm). Despite the occurrence of gold grains, the bulk rock contains not more than ∼19 ppb Au.

The magmatic origin of gold is inferred from the heterogeneous distribution of the grains in the rock, the shape of the grains (which is comparable to that of gold grains crystallized experimentally from mafic liquids) and from the As-Sb-S-Cl-poor composition of the bulk rock. The Pd/Ir and Au/Pd ratios, little affected by the early segregation of olivine (∼10 vol.%), support an Au- and PGE-rich composition of the mantle source. The low f O2 (≈IW) and the complexing with F and alkalies probably favoured partitioning of Au and PGE into the lamproite magma.

Tomichite, (V,Fe)4Ti3AsO13(OH), a new mineral species related to derbylite, has been found in the ‘green leader’ gold lodes at Kalgoorlie, Western Australia. It is monoclinic, with space group P21/m or P21; a = 7.119 (3), b = 14.176 (5), c = 4.992 (2) Å, β = 105.05 (I)°, Z = 2. Strongest diffraction lines: 3.092 (4), 2.836 (9), 2.663 (10), 1.572 (5). Tomichite occurs as tiny euhedral crystals in quartz; associated minerals are vanadian muscovite, rutile, pyrite, and calaverite. Tomichite is black, has a black streak, lacks internal reflections, is moderately anisotropic, and has S.G. = 4.16 (meas.), 4.42 (calc.). Reflectivity values are 470 nm-15.9%, 546 nm-16.3%, 589 nm 16.6%. Microhardness is VHN 800, using 50 g load.

Colourless, purple, and pink topaz and transparent quartz crystals have been found in calcite veins (with or without milky quartz) in calcareous rocks near Katlang (34° 24′ N, 72° 6′ E), Mardan district. The veins do not contain any fluorite nor the country rocks any topaz. The topaz and transparent quartz crystals are mostly broken and perfectly euhedral outlines are very rare. Refractive indices, 2V, specific gravity, and the fluorine (determined) and H2O + (calculated) contents of two topaz crystals are suggestive of their high 100 OH/(OH+F) ratios (> 25). Rather than being derived, the topaz may have formed in situ by hydrothermal/pneumatolytic activity, followed by tectonic movements that fractured the crystals and resulted in their incorporation in later-formed vein calcite.

Tantal-aeschynite occurs as idiomorphic metamict crystals in the Raposa pegmatite at São José do Sabugí, Paraíba State, NE. Brazil. Morphological data, microscopic properties, and differential thermal analysis results are given. Electron-microprobe analyses yielded a formula: {Ca0·28(Yt,Ln)0·425(Th,U)0·11}(Ta0·75Ti0·62Nb0·595Fe0·05)O6. Yttrium is the predominant rare-earth element, with cerium and neodymium as most abundant lanthanides. The tantal-aeschynite unit cell has (after heating) a 5·34, b 10·97, c 7·38 Å. An indexed X-ray powder pattern (similar to that of aeschynite) is presented.

A skarn mineral assemblage occurs at the junction between vent pyroclastics and a xenolithic Cretaceous chalk block which subsided into the collapsed caldera of the Central Ring Complex, Isle of Arran, Scotland. Adjacent to the metachalk marble an andradite garnet exoskarn zone has developed at the expense of the carbonate. An andradite grossular/diopsidic clinopyroxene endoskarn zone has formed in the surrounding agglomerate, and a magnetite exoskarn is present in places between the andradite and garnet/pyroxene zones. The andraditic exoskarn garnets have fluor-hydrogarnet components, indicating that fluorine was present in the metasomatic fluid. From petrographic evidence, three distinct episodes of exoskarn garnet crystallization can be recognized, in which the fluor-hydrogarnet component steadily increased as a function of time, which probably reflects falling temperature. The REE compositions of the exoskarn minerals are regarded as having been largely inherited from the carbonate, and the exoskarn garnets increasingly fractionated HREE with time. The endoskarn and agglomerate have also been epidotized. The REE signatures of epidotes appear to be inherited partially from precursor clinopyroxenes or feldspars, which have been replaced by epidote. Late-stage vein minerals include prehnite, laumontite and K-rich laumontite, and their REE compositions appear to have been derived from the marble, probably via REE fluoro-complexes in the fluid.

The ignimbrites of the northeast Niğde area, which are subdivided into the Lower, Middle and Upper ignimbrites on the basis of their compositional and stratigraphical characteristics, display textural variations from the base to the top. A large proportion of these ignimbrites have been altered and recrystallized by the processes of compaction, welding and devitrification, and as a result of volatile movement. The alteration and recrystallization processes include four stages: hydration, glassy and spherulitic stages accompanied by vapour-phase crystallisation. In the early phases of devitrification, detailed shard shapes are easily recognisable with the scanning electron microscope, but as alteration proceeds clarity of detail disappears because compaction results in collapse of the structure of the rock. Spherulitic and vapour-phase crystallisation usually involves the growth of alkali feldspar and cristobalite. These later stages are more common in the Upper Ignimbrite than the Middle and Lower ignimbrites.

Inclusions of platinum-group minerals (PGM) within alluvial isoferroplatinum nuggets from the Freetown Peninsula, Sierra Leone, are aligned with their shape determined by the structure of their host. The edges of the majority of the inclusions lie at 0°, 45° or 90° to external crystal edges of the nugget which shows that the inclusions are not randomly oriented earlier minerals incorporated within their host. The inclusions are later infills, probably formed at the surface of the nugget during growth and subsequently enclosed by the growing nugget. PGM on the present surface of the nugget represent the last stage of this partnership. A single nugget containing abundant inclusions is described here but similar features are observed in other nuggets from the same area. The inclusions contain laurite (RuS2), irarsite–hollingworthite (IrAsS–RhAsS), Pd–Te–Bi–Sb phases, Ir-alloy, Os-alloy, Pd-bearing Au, an Rh–Te phase, Pd–Au alloy and Pd–Pt–Cu alloy. PGM found on the nugget surface include laurite, irarsite and cuprorhodsite (CuRh2S4). The Pd–Te–Bi–Sb phases may include Sb-rich keithconnite (Pd20S7) and compositions close to the kotulskite–sobolevskite solid-solution series (PdTe–BiTe). Textural evidence suggests that formation of the nuggets began with the isoferroplatinum host and the voids were filled starting intergrowths of laurite and irarsite–hollingworthite with both laurite and irarsite–hollingworthite often showing compositional zonation and each of them replacing the other. Filling of the voids probably continued with Pd-Cu-bearing gold, Sb-rich keithconnite (Pd,Pt)20.06(Te,Sb,Bi)6.94, keithconnite, telluropalladinite Pd9(Te,Bi)4, RhTe and finally Ir-alloy and then Os-alloy. The nuggets are thought to be neoform growths in the organic- and bacterial-rich soils of the tropical rain forest cover of the Freetown intrusion. The mineralogical assemblage in the layered gabbros of the intrusion has been previously shown to differ from the alluvial assemblage in the rivers and these inclusions, not seen in Pt3Fe in the unaltered rocks, add a further item to the catalogue of differences.

The Duotoushan deposit is an important Fe–Cu deposit in the Aqishan–Yamansu metallogenic belt of eastern Tianshan, NW China. Magnetite occurs in two main habits which are common in many Fe–Cu deposits, i.e. platy (TD1 Mag) and granular magnetite (TD2 Mag) have been identified at Duotoushan. Platy magnetite shows two different zones (bright and dark) based on the observations by scanning electron microscopy. The bright part (TD1-L) is the main part of TD1 magnetite and lacks inclusions. The dark part (TD1-D) is very porous and has abundant tiny silicate inclusions. Granular magnetite is usually anhedral with obvious oscillatory zoning in back-scattered electron images. In general, the dark zones of magnetite are characterised by greater Si, Ca, Al and lesser Fe contents than the bright zones. In situ X-ray diffraction (XRD) analysis shows that the lattice parameter of TD1 magnetite is approximately equal to that of standard magnetite and slightly higher than that of TD2 magnetite, indicating that some cations with ionic radii smaller than those of Fe2+ or Fe3+ entered the magnetite lattice by simple or coupled substitution mechanisms in TD2 magnetite.

The results in the present study show that the effects of temperature and $f_{{\rm O}_ 2}$ on platy magnetite are very limited and the changing fluid composition might be the major controlling factor for the formation of Duotoushan platy magnetite. Although the possibility that mushketovite transformed from hematite cannot be excluded entirely, evidence from in situ XRD data, pore-volume ratio calculation and the growth habit of intergrown minerals indicates that platy magnetite (TD1) coexisting with amphibole was more likely to have been precipitated originally from hydrothermal fluid. This was then affected by changes in the fluid composition which consequently led to dissolution of primary magnetite (TD1-L) and re-precipitation of TD1-D magnetite (with abundant porosity and mineral inclusions). Meanwhile, granular magnetite (TD2) with oscillatory zoning, and coexisting with epidote and quartz, was precipitated from fluid with periodic variation in temperature. These oscillatory zones are characterised by bands enriched in Si, Al and Ca alternating with bands depleted in these elements. The present investigation revealed a complex evolutionary process for magnetite formation in the Duotoushan deposit. The importance of combined investigation of texture and compositional characterisation of magnetite for study of the ore genesis and evolution of Fe–Cu deposits is highlighted.

The structure of corundum is not amenable to accommodating beryllium, yet Be is commonly added to corundum for purposes of colour modification. Where the main sites in corundum are octahedrally coordinated, Be is tetrahedrally coordinated in all known Be minerals. To attempt to explain this discrepancy, the configurations of Be in the Be–Al–O±H system were determined using density functional theory (DFT). In the Be–Al–O system, the most likely Be configuration is in triangular coordination, replacing Al and bonded to three oxygen on the basal plane (large triangle) of the Al-vacant octahedral site. When H is added, OH groups form at the opposite face of the same octahedron, pointing either into or out of the site. Be–H (beryllium hydride) defects are also stable at the DFT level, with Be bonded to three O and one H. As some defects contain O–H or Be–H bonds, the DFT calculations can be corroborated by FTIR spectroscopy. Spectra recorded from 1000 corundum crystals with elevated Be confirm that bands centred at 3062 and 2490 cm–1 correspond to Be-associated defects. Polarised spectra show that the band at 2490 cm–1 resolves into two, one centred at 2491 cm–1, with a shoulder at 2523 cm–1, one of which is probably associated with a Be–H bond. The 3062 cm–1 band resolves into at least three, including a major band at 3058 cm–1, a shoulder at 3140 cm–1 and a small, sharp band at 3082 cm–1. Whilst there are caveats relating to curve fitting and baseline subtraction, the 3058 cm–1 band can probably be attributed to the defect where H points into the Al-vacant octahedral site, and the 3140 cm–1 band to the defect where the H points out. To our knowledge, this is the first occurrence of Be in triangular coordination proposed for a naturally occurring mineral. This substitution mechanism may also explain the high diffusivity of Be, as Be is effectively associated with its own Al vacancy.

Bostwickite, CaMn63+Si3O16-7H2O, is a new species from the Franklin Mine, Franklin, New Jersey. Chemical analysis yielded MgO 0.9, CaO 5.1, Mn2O3 56.3, Fe2O3 0.5, Al2O3 1.0, As2O5 1.0, SiO2 20.1, H2O [15.1], sum = 100.0%. This yields (Ca0.76Mg0.19)Σ0.95(Mn5.973+Fe0.053+)Σ6.02(Si2.80Al0.16As0.075+)Σ6.02(Si2.80Al0.16AS5+0.07)Σ3.03O16·7.01H2O, corresponding to the idealized formula. The strongest lines in the X-ray powder diffraction pattern are (d, I): 11.3, 100; 3.548, 30; 2.898, 30; 2.567, 40; 2.262, 25; 2.238, 25; 1.470, 25. Bostwickite is dark red in colour; hardness c. 1 (Mohs'); density (meas.)= 2.93 g/cm3. It occurs in radial aggregates of acicular compound crystals. Optically, bostwickite is biaxial negative with 2Vα = 25deg; α = 1.775, Β = 1.798, γ = 1.800;, dispersion strong, r > v; strongly pleochroic with α = β redbrown, γ = yellow-brown; absorption is α = β = γ. Bostwickite is named in honour of Richard C. Bostwick, collector and compiler of data on the minerals of Franklin and Sterling Hill.

The hydrocerussite-related phase, NaPb5(CO3)4(OH)3, has been found as colourless lamellar crystals in cavities within a pebble of the ancient marine slag collected in the Pacha Limani area of the Lavrion mining district, Attiki, Greece. This phase of anthropogenic origin was characterized by electron microprobe, infrared spectroscopy, powder and single-crystal X-ray diffraction. The unique crystal structure (P63/mmc, a = 5.2533(11), c = 29.425(6) Å, V = 703.3(3) Å3 and R1 = 0.047) is based upon structurally and chemically different electroneutral blocks. Each of the blocks can be split into separate sheets. The outer sheets in each block are topologically identical and have the composition [PbCO3]0. The [Pb(OH)2]0 lead hydroxide sheet is sandwiched between the two [PbCO3]0 sheets resulting in the formation of the first block [Pb3(OH)2(CO3)2]0 structurally and compositionally identical to that one in hydrocerussite Pb3(OH)2(CO3)2. Similarly the [Na(OH)]0 sheet is sandwiched between another two [PbCO3]0 sheets thus forming the [NaPb2(OH)(CO3)2]0 block described previously in the structure of abellaite NaPb2(OH)(CO3)2. Stereochemically active lone electron pairs on Pb2+ cations are located between the blocks. There are two blocks of each type per unit cell, which corresponds to the following formula: [Pb3(OH)2(CO3)2][NaPb2(OH)(CO3)2] or NaPb5(CO3)4(OH)3 in the simplified representation. The formation of NaPb5(CO3)4(OH)3 in Lavrion slags is by the contact of lead-rich slags with the sea water over the last two thousand years.

Previously, it has been suggested that metal ions complexed to humic acid in the environment might show slower dissociation than those added to humic substances in the laboratory, which has serious implications for the transport of radionuclides in the environment. The dissociation of lanthanide and anthropogenic actinide ions from humic substance complexes has been studied as a function of humic concentration and metal ion:humic concentration ratio. The results suggest that the apparently slower kinetics observed for metal ions complexed in the environment are probably due to the large humic concentrations that are used in those studies. Further, there is no evidence that the dissociation rate constant varies at very low metal ion concentrations. Although humic samples size-fractionated by ultrafiltration showed that more metal may be bound non-exchangeably, there was no evidence for different rate constants. Ultrafiltration of Eu(III)/humic acid mixtures did show a shift in Eu from smaller to larger fractions over a period of two days. Therefore, the results suggest that dissociation rate constants determined in the laboratory at metal ion concentrations higher than those expected in the environment may be used in predicting radionuclide mobility, provided that the humic acid concentration is in the range expected at the site.

Kyawthuite, Bi3+Sb5+O4, is a new gem mineral found as a waterworn crystal in alluvium at Chaung-gyi-ah-le-ywa in the Chaung-gyi valley, near Mogok, Burma (Myanmar). Its description is based upon a single sample, which was faceted into a 1.61-carat gem.The composition suggests that the mineral formed in a pegmatite. Kyawthuite is monoclinic, space group I2/c, with unit cell dimensions a = 5.4624(4), b = 4.88519(17), c = 11.8520(8) Å, β = 101.195(7)°, V = 310.25(3) Å3and Z = 4. The colour is reddish orange and the streak is white. It is transparent with adamantine lustre. The Mohs hardness is 5½. Kyawthuite is brittle with a conchoidal fracture and three cleavages: {001} perfect, {110} and {110} good. The measured density is 8.256(5) g cm–3and the calculated density is 8.127 g cm–3. The mineral is optically biaxial with 2V = 90(2)°. The predicted indices of refraction are α = 2.194, β = 2.268, γ = 2.350. Pleochroism is imperceptible and the optical orientation is X = b; Y≈ c; Z ≈ a. Electron microprobe analyses, provided the empirical formula (Bi0.823+Sb0.183+)∑1.00(Sb0.995+Ta0.015+)∑1.00O4. The Raman spectrumis similar to that of synthetic Bi3+Sb5+O4. The infrared spectrum shows a trace amount of OH/H2O. The eight strongest powder X-ray diffraction lines are [dobs in Å(I)(hkl)]: 3.266(100)(112), 2.900(66)(112), 2.678(24)(200), 2.437(22)(020,114), 1.8663(21)(024), 1.8026(43)(116,220,204), 1.6264(23)(224,116) and 1.5288(28)(312,132). In the crystal structure of kyawthuite (R1 = 0.0269 for 593 reflections with Fo > 4σF), Sb5+O6 octahedrashare corners to form chequerboard-like sheets parallel to {001}. Atoms of Bi3+, located above and below the open squares in the sheets, form bonds to the O atoms in the sheets, thereby linking adjacent sheets into a framework. The Bi3+ atom is in lopsided 8 coordination,typical of a cation with stereoactive lone electron pairs. Kyawthuite is isostructural with synthetic β-Sb2O4 and clinocervantite (natural β-Sb2O4).

Eudialyte-related compounds have been synthesised hydrothermally at T = 600°C and P = 2 kbar from a stoichiometric mixture of Na2CO3, CaO, Fe2O3, ZrOCl2 and SiO2 using the Na:Ca:Fe:Zr:Si ratios corresponding to the eudialyte end-member Na15Ca6Fe3Zr3Si(Si25O73)(OH)Cl2⋅H2O, in the presence of 1 M aqueous solutions of NaCl and NaF. The synthesis was carried out in platinum ampoules over 10 days. Natural raslakite (a Ca-deficient member of the eudialyte group) was used as a seed and added in amounts corresponding to 2 wt.% of the whole charge. The products were characterised by powder X-ray diffraction, IR and Raman spectroscopy, morphological features, and electron probe microanalyses. In experiments with NaCl, almost pure eudialyte-type compounds were obtained. Synthesis in the presence of a NaF solution resulted in the formation of a F-dominant eudialyte-type compound related to raslakite as the main product and aegirine, vlasovite and lalondeite as by-products. All synthesised eudialyte-type compounds are Zr-rich and Fe-deficient, similar to eudialyte-group minerals from hyperagpaitic rocks related to foyaites. The increased NaCl contents in the reaction system results in increased Ca content in the synthesised eudialyte-related compounds. The crystal-chemical formulae of the synthesised eudialyte-type compounds are derived based on general regularities established earlier for eudialyte-group minerals.