Biotites from a number of granites have been analysed for major oxides and a wide range of trace elements. Their compositions are found to be typical of biotites from granite and to show element fractionation in presumed differentiation series. Estimates are made of the fugacity of oxygen and water during the crystallization of the granites. PH2O is found to increase slightly through the differentiation series, and fO2, for a temperature of 700°C is estimated to be between 10−18 and 10−12. Tin mineralization is connected with the igneous rocks and the relationship of tin in the micas to the rock compositions is described and the factors controlling the distribution of tin are discussed. The biotites have only up to 21 % of the tin of the granites. In general Sn increases in the biotites with decreasing temperature of equilibration and with increase in the degree of albitization of the granites. High Sn in biotites seems to be an indicator of potential mineralization.

Mereheadite, ideally Pb2O(OH)Cl, is a new mineral related to litharge and which is structurally similar to synthetic bismuth-oxyhalides. With other lead- and lead-copper oxychlorides, it occupies lenses and cavities in veins of manganese and iron oxide minerals which cut through a sequence of dolomitic limestones at Merehead quarry, Cranmore, Somerset (51°12′N, 2°26′W) Mereheadite is pale yellow to reddish-orange, transparent to translucent and has a white streak and a vitreous or resinous lustre. It is not fluorescent. Individual grains, up to a few mm across, cluster together in compact masses of 10–30 mm in size, but discrete crystals have not been observed. Specular reflectance data on randomly orientated grains from 400 to 700 nm are provided, and refractive indices calculated from these at 590 nm range from 2.19 to 2.28. H = 3.5, VHN100 = 171, D(meas) = 7.12(10) g/cm3, Dcalc = 7.31 g/cm3. The mineral is brittle with an uneven, conchoidal to hackly fracture and has a perfect (001) cleavage which is parallel to the sheets of PbO and Cl. It is intimately associated with mendipite, blixite, cerussite, hydrocerussite and calcite in lenses and pods in the veins. Other minerals which occupy cavities in these veins include chloroxiphite, paralaurionite, parkinsonite and the borosilicate datolite. Mereheadite is monoclinic, space group C2/c, and its cell parameters, refined from powder X-ray diffraction are: a = 5.680(2), b = 5.565(3), c = 13.143(9) Å, β=90.64(4)°, V = 415.4 (8) Å3, Z = 4. The ten strongest reflections in the X-ray powder diffraction pattern are [d in Å, (I, hkl)]: 2.930(10,113), 3.785(5,111, –111), 2.825(4,200), 6.581(4,002), 2.182(4,115), 2.780(4,020), 3.267(4,004), 1.980(3,–220), 1.695(3,224,132,117), 1.716(3,026). Its empirical formula is Pb8O4.19(BO3)0.51 (CO3)0.62(OH)0.76Cl4.09. Although it is very similar chemically to blixite, it has notably different cell parameters. There is some uncertainty about the essential nature of boron and carbon in natural mereheadite. This stems from the impossibility of ensuring the purity of samples for wet-chemical analysis, and from the predominance of lead in the structure of the mineral which has meant that the location of boron and carbon within the mereheadite structure is unresolved, 11B MAS NMR does show, however, that boron is present as BO3 groups. The structure consists of alternating PbO sheets and layers of chlorine atoms. Each lead atom is coordinated to four chlorines and four O/OH in a square antiprism configuration. As such, it is structurally-related to nadorite, thorikosite and schwartzembergite. Comparisons with structurally analogous phases such as bismuth oxychlorides and bismutite (Bi2O2CO3) suggest that the BO3 and CO3 groups are likely to replace chlorine in the layer between PbO sheets. The composition of natural mereheadite is defined by three end-members: the mereheadite end-member Pb2O(OH)Cl, and two fictive end-members Pb2(OH)2CO3 and Pb4O(OH)3BO3.

The Galway Granite often has a highly siliceous aphyric alkali granite at the margin, followed inwards by a K-feldspar phenocrystic adamellite and then a steeply layered granodiorite. This previously puzzling arrangement, which seemed to conflict with the necessity to cool from the periphery and crystallize the most basic granite at the margin, is examined by a traverse of chemically analysed rocks and biotites. The Mg/(Mg+Fe+Mn) values indicate that the granodiorite probably crystallized from the outside inwards. The marginal aphyric granite crystallized from the acid residuum in the nearly solid adamellite. This was drawn out of the adamellite by blocks of country rock falling into the adamellite and creating a zone of rarefaction behind them. This also explains the absence of a chilled margin and the aplitic texture and mineralogy of the aphyric granite. The adamellite largely accumulated by crystal settling with gravity grading but the granodiorite crystallized in vertical layers during upward vertical movements of the magma that tipped up the gravity layering in the adamellite. Scattered microdioritic xenoliths are postulated to be disrupted dykes. Eighteen granite and twenty-seven biotite analyses are tabulated.

In the United Kingdom, disposal of radioactive waste may involve packages of grouted waste being placed in a geological disposal facility (GDF) and surrounded by a cementitious backfill. This paper describes modelling that has been carried out to develop an understanding of the possible spatial and temporal evolution within the GDF.

A single waste package is assumed to be filled with an encapsulation grout, placed in an underground vault and surrounded by a cementitious backfill. Groundwater from the host rock flows into the vault and through the backfill. A simplified model system examines the interactions between groundwater, cementitious backfill and grout.

In most cases the model predicts a reduction in the backfill porosity due to precipitation and dissolution reactions, particularly at the upstream edge of the vault. The degree to which this occurs depends on the groundwater composition. The model also predicts precipitation and dissolution reactions would occur in the grouts close to their interface with the backfill, reducing the local porosity significantly which may isolate the grouts from the backfill, so that the pH within the grouts would be unchanged over an extended period.

Metahalloysite is one of the kaolin group of minerals with a composition approximating to the formuia Al2O3.2SiO2.2H2O, and its structure is generally considered to be built of composite layers of atoms of the kind found in other minerals of this group. It differs from them most strikingly in that it can be produced by the dehydration of the hydrated mineral halloysite, which has the approximate composition Al2O3.2SiO2.4H2O. Both minerals give comparatively poor X-ray diagranm showing relatively few lines attd bands. The lines correspond to reflections from a basal spacing of about 7·2 Å. in metahalloysite and 10·1 Å. in halloysite.

The distribution of As and Sb in a series of Skaergaard rocks and some of their minerals has been investigated using neutron activation analysis, and the geochemical behaviour of these elements during the fractionation of a basic magma is discussed.

It is concluded that As3+ is probably accepted into octahedral lattice sites usually occupied by Fe3+, Mg2+, Ti4+, and Al3+, and that there is also some substitution of As5+ for Si4+ and Al3+ in tetrahedral sites. There is a strong tendency for the element to concentrate in both interstitial and late-stage liquids.

Sb seems to show a marked preferential entry into early (magnesian) olivines, as in the case of Ni. The analytical results indicate that the substitution of Sb3+ for Fe2+ probably accounts for most of the Sb in silicate and oxide minerals. The tendency for Sb to concentrate in the residual Skaergaard liquids is less marked than in the case of As, but greater than in the cases of V, Cr, and Ni.

As and Sb have also been determined in four chondritic meteorites, in which the As/Sb ratio ranges from 8·5–12·4. Analyses for As and Sb in the standard rock powders G-1 and W-1 have also been made.

The earthworm calciferous gland produces a concentrated suspension of calcium carbonate and in certain species precipitates as concretions of CaCO3, which then enter the soil. Here we investigated the initial stages of CaCO3 formation in the earthworm Lumbricus friendi by means of Fourier transform infrared and electron microscopy techniques (field-emission scanning electron microscopy, transmission electron microscopy, high resolution electron microscopy and selected area electron diffraction). In addition, comparisons between the IR spectra of the water-dissolved carbonic anhydrase (CA) and the glandular secretion (‘milky fluid’) were performed in order to investigate the mechanisms involved in CaCO3 precipitation. Our results strongly suggest that carbonation starts with the dissolved CO2, which is transformed via deprotonation to HCO3-, then to CO32- and finally to amorphous calcium carbonate (ACC). While ACC stabilization takes place under the biological control, further transformation stages leading to calcite concretions seem to be inorganically driven by an Ostwald ripening process.

Found on a specimen in the mineral collection of the National Museum of Wales, no. NMW 27.111.GR414, from the Aberllyn mine, Llanrwst mining field, North Wales, with hydrozincite on a breccia cemented by sphalerite, quartz, calcite, and ankerite. Atomic absorption and TGA analyses gave ZnO 37.8, CuO 22.0, SO3 14.9, H2O 24.5, total 99.2%, corresponding to (Zn2.50 Cu1.49)Σ3.99 S1.00 O7·7.32 H2O on the basis of total O = 7 in the anhydrous part. The ideal formula is (Zn,Cu)4SO4(OH)6·4H2O where Zn > Cu. It is hexagonal a 8.29, c 10.50 ± 0.01 Å, possible space groups P6, P, P6/m, P622, P6mm, Pm2, P2m, and P6/mmm. Isomorphous with synthetic Zn,SO4(OH)66·4H2O and (Zn,Cu)4SO4(OH)6·4H2O. Strongest X-ray powder diffractions are: 10.59(100)0001, 5.31(15)0002, 4.15(25)110, 2.71(42)210, 2.63(41)211,0004, 2.41(22)212, 1.57(23)322, 1.55(20)411. Namuwite is pale sea-green in colour, lustre pearly, streak very pale green, H (Mohs) 2. Cleavage {0001}, perfect. Density (g/cm3) 2.77 (meas.), 2.81 (calc. on the normalized empirical formula). It is optically uniaxial, sign not determined owing to the extremely low birefringence. Refractive index n = 1.577(5)(NaD). The mineral and name have been approved by the Commission on New Minerals and Mineral Names, IMA.

Bluebellite, Cu6[I5+O3(OH)3](OH)7Cl and mojaveite, Cu6[Te6+O4(OH)2](OH)7Cl, are new secondary copper minerals from the Mojave Desert. The type locality for bluebellite is the D shaft, Blue Bell claims, near Baker, San Bernardino County, California, while cotype localities for mojaveite are the E pit at Blue Bell claims and also the Bird Nest drift, Otto Mountain, also near Baker. The two minerals are very similar in their properties. Bluebellite is associated particularly with murdochite, but also with calcite, fluorite, hemimorphite and rarely dioptase in a highly siliceous hornfels. It forms bright bluishgreen plates or flakes up to ~20 mm 620 mm 65 mm in size that are usually curved. The streak is pale bluish green and the lustre is adamantine, but often appears dull because of surface roughness. It is non-fluorescent. Bluebellite is very soft (Mohs hardness ~1), sectile, has perfect cleavage on {001} and an irregular fracture. The calculated density based on the empirical formula is 4.746 g cm–3. Bluebellite is uniaxial (–), with mean refractive index estimated as 1.96 from the Gladstone-Dale relationship. It is pleochroic O (bluish green) >> E (nearly colourless). Electron microprobe analyses gave the empirical formula Cu5.82I0.99Al0.02Si0.12O3.11(OH)9.80Cl1.09 based on 14 (O+Cl) a.p.f.u. The Raman spectrum shows strong iodate-related bands at 680, 611 and 254 cm–1. Bluebellite is trigonal, space group R3, with the unit-cell parameters: a = 8.3017(5), c = 13.259(1) Å , V = 791.4(1) Å 3 and Z = 3. The eight strongest lines in the powder X-ray diffraction (XRD) pattern are [dobs/Å (I) (hkl)]: 4.427(99)(003), 2.664(35)(211), 2.516(100)(21), 2.213(9)(006), 2.103(29)(033,214), 1.899(47)(312,21), 1.566(48)(140,217) and 1.479(29)(045,14,324).

Mojaveite occurs at the Blue Bell claims in direct association with cerussite, chlorargyrite, chrysocolla, hemimorphite, kettnerite, perite, quartz and wulfenite, while at the Bird Nest drift, it is associated with andradite, chrysocolla, cerussite, burckhardtite, galena, goethite, khinite, mcalpineite, thorneite, timroseite, paratimroseite, quartz and wulfenite. It has also been found at the Aga mine, Otto Mountain, with cerussite, chrysocolla, khinite, perite and quartz. Mojaveite occurs as irregular aggregates of greenish-blue plates flattened on {001} and often curved, which rarely show a hexagonal outline, and also occurs as compact balls, from sky blue to medium greenish blue in colour. Aggregates and balls are up to 0.5 mm in size. The streak of mojaveite is pale greenish blue, while the lustre may be adamantine, pearly or dull, and it is non-fluorescent. The Mohs hardness is ~1. It is sectile, with perfect cleavage on {001} and an irregular fracture. The calculated density is 4.886 g cm–3, based on the empirical formulae and unit-cell dimensions. Mojaveite is uniaxial (–), with mean refractive index estimated as 1.95 from the Gladstone-Dale relationship. It is pleochroic O (greenish blue) >> E (light greenish blue). The empirical formula for mojaveite, based on 14 (O+Cl) a.p.f.u., is Cu5.92Te1.00Pb0.08Bi0.01O4(OH)8.94Cl1.06. The most intense Raman bands occur at 694, 654 (poorly resolved), 624, 611 and 254 cm–1. Mojaveite is trigonal, space group R3, with the unit-cell parameters: a = 8.316(2), c = 13.202(6) Å and V = 790.7(1) Å 3. The eight strongest lines in the powder XRD pattern are [dobs/Å (I) (hkl)]: 4.403(91)(003), 2.672(28)(211), 2.512(100)(21), 2.110(27)(033,214), 1.889(34)(312,21,22), 1.570(39)(404,140,217), 1.481(34)(045,14,324) and 1.338(14)(422). Diffraction data could not be refined, but stoichiometries and unit-cell parameters imply that bluebellite and mojaveite are very similar in crystal structure. Structure models that satisfy bondvalence requirements are presented that are based on stackings of brucite-like Cu6MX14 layers, where M = (I or Te) and X = (O, OH and Cl). Bluebellite and mojaveite provide a rare instance of isotypy between an iodate containing I5+ with a stereoactive lone electron pair and a tellurate containing Te6+ with no lone pair.

Anomalous iron meteorites are those which do not have Ni, Ga, and Ge contents appropriate to one of the twelve chemical groups; they account for 14% of all irons. The chemistry of irons in the twelve groups can be largely understood in terms of primary fractionation in the nebula, which established the bulk composition of the groups, and secondary fractionation in the parent bodies (probably fractional crystallization), which produced the chemical trends within groups. Logarithmic element-Ga graphs containing data for groups and anomalous irons reveal that anomalous irons experienced the same primary and secondary fractionations as affected the groups.

The uniformity of chemical trends within groups allows possible genetic relationships between anomalous irons and groups and among anomalous irons to be tested. It is concluded that the sixty-nine anomalous irons are samples from fifty-odd additional groups, which had similar histories to the twelve groups. Less than five of the anomalous irons could be compositional end- members or reprocessed irons from the groups.

Because ‘anomalous’ means abnormal, some other term for the irons which do not belong to the twelve groups would be a useful reminder that these irons formed in a similar way to irons in the major groups. They could be called members of minor groups or grouplets.

Zeolites K-F and W (EDI and MER types) were synthesized hydrothermally using a natural rock as raw material. Chemical treatments were carried out on a diatomitic rock (containing opaline silica) from Crotone (Calabria, Italy) in order to separate/obtain potassium silicate, a reagent necessary for synthesizing zeolites. Synthesis experiments were performed by mixing the obtained siliceous solution with potassium hydroxide and alumina in varying proportions at 150°C and room pressure. Four synthesis series were performed to form zeolite K-F (EDI) and zeolite W (MER).

The chemical-physical and morphological characterization of the zeolite phases were carried out. Cell parameters were calculated using the Rietveld method. Infrared, thermal and nuclear magnetic resonance (29Si) experiments confirmed the high quality of the zeolite products. The amorphous phase in the synthesis powders was estimated with quantitative phase analysis using the combined Rietveld and reference intensity ratio methods.

Recent TEM observations of two-phase microstructures and associated crystal defects in selected, rare dolomites have been extended to calcite-structured (R3̄c) carbonates and to other natural and synthetic carbonates that crystallize with the dolomite (R3̄) structure. The samples included siderites (FeCO3), smithsonites (ZnCO3), ankerites (Ca[Mg,Fe](CO3)2), and kutnahorites (Ca[Mn,Fe](CO3)2).

TEM methods show that the forms of second phases which result from the presence of common, divalent, metallic impurities are morphologically similar in R3̄c and R3̄ carbonates and occur more widely than hitherto realized. The most common form consists of thin ribbons of second phase which are coherent with and have the same crystallographic orientation as the host carbonate. Another form of microstructure, manifest as modulations in diffraction contrast, appears to be associated with incipient breakdown of single-phase carbonate. The results of extensive TEM/EDS microanalyses show that in siderite and ankerite the formation of ribbons is promoted by Ca impurity or Ca excess (with respect to R3̄c stoichiometry). In smithsonite, Cu and Ca impurities can play similar roles in relation to modulated microstructures. In kutnahorites, the perfection of grains and the absence of second-phase effects is strongly dependent on the ratio of Fe to Mn but is also affected by Ca in excess of the stoichiometric requirement. Electron diffraction results from several of the minerals show c-type spots, which can be interpreted as indicating ordering within basal layers of cations.

The results show that, by correlating analytical TEM data with the study of second phases and incipient two-phase microstructures, it should be possible to determine the limits of solid solubility in carbonate systems.

Illite crystallinity determinations on Palaeozoic pelitic rocks, whose stratigraphic range runs from Lower Cambrian to Westphalian, indicate that anchimetamorphism has affected both the Lower and Upper Palaeozoic sequences. Two metamorphic episodes are in evidence, with the earlier, Caledonian, being of slightly higher grade. The higher anchizone crystallinity values are recorded from the Fishguard area in which mineral assemblages of the prehnite-pumpellyite facies have recently been recognized in basic igneous rocks. The later metamorphic episode has affected rocks to the south of the Variscan front. Here crystallinity values are low anchizone but some straddle the boundary with the diagenetic state. The Pembroke coalfield lies in this southern area and has coals largely of anthracite rank with volatile matter contents of between 10.1 and 5% Grade of metamorphism as indicated by crystallinity and by coal rank data from the Pembroke coalfield shows anomalous results to that described from the main South Wales coalfield. A neo-formed 2M illite from the Variscan spaced cleavage is described with analytical and X-ray diffraction data.

During an investigation of stibiconite and cervantite (Vitaliano and Mason, 1952) we examined many specimens of antimony ochre. The commonest mineral in these specimens proved to be stibiconite, but others were found, and to establish their identity it became necessary to study the secondary products as a group. The mineralogy of these oxygenated secondary antimony minerals presents unusual problems on account of their earthy and often inhomogeneous nature. Our experience indicates that without X-ray powder photographs it is difficult to establish the true identity of much of this material. The purpose of this paper is to present the results of our investigations and to provide more adequate descriptions of some little-known species.

A thin (100 m) cover of flat-lying, Recent, calcite-rich tuff at Ndale near Fort Portal, Uganda, unconformably overlies steeply dipping Precambrian metamorphic rocks. It is locally radioactive owing to uranium-rich pyrochlore minerals and lesser amounts of zircon, monazite, titanite, and an unidentified thorium phosphate. In one concentrate, four grains of uranpyrochlore and one grain of uranoan pyrochlore showed a positive linear correlation of Ti with U, and negative linear correlations of Ti with Na, F and Sr. Ta remained high and relatively constant [11 anal., ave. 14.5 (0.6)% Ta2O5]. In the same concentrate the composition of a separate grain of uranoan pyrochlore did not plot on these lines and Ta was comparatively low [2 anal., ave. 4.5 (0.3)% Ta2O5]. The data suggest two separate paths of differentiation. However, zoned grains were not observed. Unit cells were cubic with a = 10.351 ± 0.002 Å for a grain with 12.9% UO2tot and 10.333 ± 0.002 Å for a grain with 26.6% UO2tot. On heating in air the cell size decreased, possibly due to oxidation of U4+. The crystalline nature of these minerals can be attributed to a very young (4000–5000 yr) geological age.

This paper reports an infrared spectroscopic study of a set of sodalite-group minerals. The specimens have been identified using a combination of X-ray diffraction and microchemical analysis. As expected, the Si/Al ratio is ~1; the extra framework cation content is characterized by a well-defined Na ⇌ (Ca+K) substitution. The lattice parameters of the studied samples range from sodalite (sample LM11) with a = 8.889(2) Å, to haüyne (sample HR3S) with a = 9.1265(2) Å. The specimens, having the SO2– group as a dominant anion, show a clear correlation between the a cell edge and the K content. Singlecrystal FTIR spectroscopy shows that haüyne and nosean typically contain enclathrated CO2 molecules, inadditionto H2O and minor carbonate, while sodalite is virtually CO2-free. Detailed microspectrometric mappings show a non-homogeneous distribution of volatile constituents across the crystals, which may be related to the presence of fractures in the crystals. Because of such zoning, a relatively wide variation is observed when calibrating extinction coefficients on the basis of a bulk analytical method such as CHN elemental analysis.

The current state of the lillianite homologous series is presented, with its two branches − the lillianite branch of the predominantly Pb-Bi-Ag sulfosalts and the andorite branch of predominantly Pb-Sb-Ag sulfosalts. Both the natural and synthetic members are discussed, especially from the structural and compositional point of view and the related, chemically distinct and structurally more complicated members of the series are described. A number of new published, or hitherto unpublished observations is given, together with fairly exhaustive tables of data. Relationships between the complex structures of different ‘andorite’ species and principal structural features of ‘oversubstituted’ As-Sb and Bi-Sb species are discussed. Contrary to many studies of this subject, synthetic phases form an integral part of the paper. It is concluded that research in this long-known homologous series still supplies new interesting phases, especially in the fields of synthetic products and in its andorite branch.

In the large serpentinite body at Zöblitz, which is part of the Gneiss-Eclogite Unit of the Saxonian Erzgebirge, ilmenite rods have been detected in olivine. Although these rods are ≤1 μm wide, they can be unequivocally identified as ilmenite using electron backscatter diffraction. We also applied this method to prove that ilmenite is topotactically intergrown with the olivine host ([100]ol ‖ [001]ilm). This relation was found previously, e.g. for ilmenite exsolved from olivine of garnet peridotite from Alpe Arami, Swiss Alps. The degree of this exsolution phenomenon in the Alpe Arami rocks was taken as an indication of the original formation of a Ti-bearing mineral at depths of ∽300 km. As in the olivines of the serpentinite from Zöblitz, the density of the ilmenite rods is significantly less than in the rock from Alpe Arami. We think that our observation is compatible with previous P-T estimates of close to 4 GPa and 1000–1100°C for the ultramafic bodies in the central Saxonian Erzgebirge.

In a previous paper (24) the writer discussed the relations between the chemical and physical properties of a number of potash-sodafelspars, mainly of the schillerized or perthitic variety, and the effect of high temperatures upon them. The present paper gives the results of further examination of these and of several additional specimens selected to make the range of composition more complete.

Twenty-six specimens were selected for this investigation. They include two albites, six microclines, and eighteen felspars which have been grouped as an orthoclase-microperthite series. The confused nomenclature of the alkali-felspars makes a choice of suitable names difficult. Alling's classification (1, pp. 253-254) represents a systematic attempt to overcome this confusion, but it seems doubtful whether some of his arbitrary subdivisions (e.g. ‘anorthoclase potentially eutectoperthite’ and ‘microcline eutectoperthite’) can exist.