The densification of pure magnesia was examined along with mixtures containing 0·5 and 1·0 mol % of calcium oxide and forsterite. The sintering behaviour at temperatures between 1400 and 1800 °C was studied and measurements made of changes in shrinkage, porosity, bulk density, and grain size for sintering times of up to 8 h at sintering temperature. It was found that both the 0·5 and 1·0 mol % additions enhanced the sintering of pure magnesia in the temperature range 1500–1700 °C Increased grain growth was found for mixtures containing forsterite but little change occurred for mixtures containing lime. Examination of the grain growth data showed that the mixtures obeyed a relationship: Time at temperature × Constant = (grain size)n, where n = 2 for the grain growth of pure magnesia and mixtures containing lime, but n = 3 for mixtures of magnesia with additions of a silicate such as forsterite. A value of 78 kcal/mole was obtained for the grain growth of pure magnesia, which agrees with other researches.

The extent of the solubility of lime in periclase for each lime-magnesia mixture at each temperature was also examined using electron probe analysis and related to the sintering behaviour observed for these mixtures.

Deerite has been found in layers of Fe-rich metasediments, metamorphosed under conditions of blueschist to eclogite facies (T = ca. 480°C). Geochemical comparisons with other deerites described in the literature show that the Ile de Groix deerites most closely resemble the Mn-poor, alpine type, and Sifnos deerites. The P-T conditions of the Ile de Groix metamorphism do not conform with the stability field of deerite. In the assemblages examined here deerite seems to be a relic from earlier stages of prograde metamorphism.

The new mineral, dyrnaesite-(La), is found in the Ilímaussaq alkaline complex, South Greenland. The holotype material originates from an arfvedsonite lujavrite sheet as an accessory mineral. Dyrnaesite-(La) is pale yellowish green, with no cleavage and an irregular fracture. Density is 3.68(2)/3.682 g/cm3 (measured/ calculated). It is biaxial, negative, 2Vα = 47(1)/48 (measured/calculated); α = 1.6226(5), β = 1.6852(10), γ = 1.6982(2); X = c, Y = a, Z = b. The average values of microprobe analyses are (wt.%) P2O5 37.17, SiO2 0.15, CaO 0.90, Na2O 20.06, La2O3 16.44, CeO2 20.23, Pr2O3 1.40, Nd2O3 3.47, Sm2O3 0.24, Dy2O3 0.06, Y2O3 0.06.

The crystal structure was solved from single-crystal X-ray diffraction data. Dyrnaesite-(La) is orthorhombic, Pnma; a = 18.4662(7) Å, b = 16.0106(5) Å, c = 7.0274(2) Å, V = 2077.7(2) Å3, Z = 4. The structural formula calculated from the diffraction data and microprobe analysis is Na7.89(Ce0.94Ca0.06)∑1.00(Ca0.12La1.14Ce0.40Pr0.10Nd0.24)∑2.00(PO4)6, the simplified formula is Na8Ce4+REE2(PO4)6. The crystal structure is related closely to that of vitusite-(Ce), but is distinct from it in several aspects. The five strongest lines of the powder X-ray diffraction pattern are (d Å, (I %), (hkl)); 6.57 (100) (101), 4.62 (40) (301, 230, 400), 3.50 (40) (331), 2.80 (86) (232, 402), 2.67 (54) (060,630).

Camptonites from the Taourirt region of Morocco contain kaersutite crystals that exhibit clear sector zoning. The electron microprobe reveals systematic variations between sectors, with preferential enrichment of Mg and Si in sector (011) and higher values for Fe, Ti and Al in sectors (110) or (100). These differences are similar to those recorded in clinopyroxenes with hour-glass zoning where this type of crystallization has been known for more than a century.

The new minerals natromarkeyite, Na2Ca8(UO2)4(CO3)13(H2O)24⋅3H2O (IMA2018-152) and pseudomarkeyite, Ca8(UO2)4(CO3)12(H2O)18⋅3H2O (IMA2018-114) were found in the Markey mine, San Juan County, Utah, USA, where they occur as secondary phases on asphaltum. Natromarkeyite properties are: untwinned blades and tablets to 0.2 mm, pale yellow green colour; transparent; white streak; bright bluish white fluorescence (405 nm laser); vitreous to pearly lustre; brittle; Mohs hardness 1½ to 2; irregular fracture; three cleavages ({001} perfect, {100} and {010} good); density = 2.70(2) g cm–3; biaxial (–) with α = 1.528(2), β = 1.532(2) and γ = 1.533(2); and pleochroism is X = pale green yellow, Y ≈ Z = light green yellow. Pseudomarkeyite properties are: twinned tapering blades and tablets to 1 mm; pale green yellow colour; transparent; white streak; bright bluish white fluorescence (405 nm laser); vitreous to pearly lustre; brittle; Mohs hardness ≈ 1; stepped fracture; three cleavages ({10$\bar{1}$} very easy, {010} good, {100} fair); density = 2.88(2) g cm–3; biaxial (–) with α = 1.549(2), β = 1.553(2) and γ = 1.557(2); and it is nonpleochroic. The Raman spectra of markeyite, natromarkeyite and pseudomarkeyite are very similar and exhibit bands consistent with UO22+, CO32– and O–H. Electron microprobe analyses provided the empirical formula Na2.01Ca7.97Mg0.03Cu2+0.05(UO2)4(CO3)13(H2O)24⋅3H2O (–0.11 H) for natromarkeyite and Ca7.95(UO2)4(CO3)12(H2O)18⋅3H2O (+0.10 H) for pseudomarkeyite. Natromarkeyite is orthorhombic, Pmmn, a = 17.8820(13), b = 18.3030(4), c = 10.2249(3) Å, V = 3336.6(3) Å3 and Z = 2. Pseudomarkeyite is monoclinic, P21/m, a = 17.531(3), b = 18.555(3), c = 9.130(3) Å, β = 103.95(3)°, V = 2882.3(13) Å3 and Z = 2. The structures of natromarkeyite (R1 = 0.0202 for 2898 I > 2σI) and pseudomarkeyite (R1 = 0.0787 for 2106 I > 2σI) contain uranyl tricarbonate clusters that are linked by (Ca/Na)–O polyhedra forming thick corrugated heteropolyhedral layers. Natromarkeyite is isostructural with markeyite; pseudomarkeyite has a very similar structure.

The new leucophosphite-group mineral ammoniotinsleyite is found in a guano deposit located on the Pabellón de Pica Mountain, Iquique Province, Tarapacá Region, Chile. Associated minerals are halite, gypsum, salammoniac and clay minerals. Ammoniotinsleyite occurs as pink to pale violet globular aggregates up to 3 mm across with individual single crystals ~10–15 μm. The mineral is brittle. Its Mohs hardness is 4. Dmeas. = 2.42(2) g cm–3 and Dcalc. = 2.451 g cm–3. The IR spectrum shows the presence of NH4+ and PO43– groups and H2O molecules. Ammoniotinsleyite is optically biaxial (+), α = 1.557(2), β = 1.559 (calc.), γ = 1.563(2) (λ = 589 nm); and 2Vmeas. = 75(10)°. The chemical composition (K, Mg, Ca, Al, Fe and P from electron-microprobe data; H, C and N measured by gas chromatography on products of ignition at 1200°C; wt.%) is: (NH4)2O 7.25, K2O 1.50, MgO 0.42, CaO 0.34, Al2O3 29.91, Fe2O3 2.36, P2O5 43.97, H2O 14.89, CO2 below detection limit, total 100.64. The empirical formula is [(NH4)0.88K0.10Ca0.02)]Σ1.00(Al1.86Fe3+0.09Mg0.03)Σ1.98(PO4)1.96(OH)1.05⋅2.11H2O. The idealised formula is (NH4)2Al2(PO4)2(OH)⋅2H2O. The crystal structure of ammoniotinsleyite was refined based on powder X-ray diffraction data, using the Rietveld method. The final agreement factors are: Rp = 0.0071, Rwp = 0.0093 and Robs = 0.0167. The new mineral is isostructural with tinsleyite, spheniscidite and leucophosphite. It is monoclinic, space group P21/n, a = 9.5871(1) Å, b = 9.6089(1) Å, c = 9.6467(2) Å, β = 103.4461(8)°, V = 864.31(2) Å3 and Z = 4. The strongest reflections of the powder X-ray diffraction pattern [d,Å(I,%)(hkl)] are: 7.56(23)($\bar{1}$01), 6.71(79)(011, 110), 5.947(100)(101, $\bar{1}$11), 4.676(36)(002, 200), 3.032(28)($\bar{1}$13, 031, 130), 2.958(25)($\bar{2}$22, 310, $\bar{1}$31) and 2.635(29)($\bar{2}$31).

Voudourisite, Cd(SO4)·H2O, and lazaridisite, Cd3(SO4)3·8H2O, are two new minerals from the Esperanza Mine, Kaminiza Area, Lavrion Mining District, Greece. This small ancient mine is also the type locality of niedermayrite and katerinopoulosite. Further associated minerals are sphalerite, galena, edwardsite, chalcanthite, gypsum and greenockite. Both secondary minerals form tiny clusters or crusts and are among the latest to form in this paragenetic sequence. They are colourless or white, transparent to translucent, with a white streak and vitreous lustre. No fluorescence is observed. The minerals exhibit conchoidal fracture, no cleavage or preferred parting. The Mohs hardness is ~3 and both have brittle tenacity. Voudourisite is biaxial (–) with refractive indices at 589(1) nm of α = 1.580(2), β = 1.624(2), γ = 1.640(2), 2Vmeas. = 70(5)°, 2Vcalc. = 61° and β ~ || [010]. Lazaridisite is biaxial neutral with refractive indices at 589(1) nm of α = 1.552(2), β = 1.561(2), γ = 1.570(2), 2Vmeas. = 90(5)° and 2Vcalc. = 90°. The chemical compositions of voudourisite and lazaridisite are close to ideal with only minor amounts of copper detectable. The atomic arrangement in voudourisite (space group P21/c with a = 7.633(2), b = 7.458(2), c = 8.151(2) Å, β = 122.35(1)° and V = 392.0(2) Å3) is related to that of kieserite while lazaridisite (space group C2/c with a = 14.813(3), b = 11.902(2), c = 9.466(2) Å, β = 97.38(1)° and V = 1655.2(6) Å3) is a distinct structure-type. Calculated densities are 3.838 and 3.088 g/cm3, respectively.

The strongest lines in the powder X-ray pattern [d in Å (I) (hkl)] are: 4.890 (66) (110); 3.741 (25) (020); 3.578 (100) (11$\bar 2$); 3.230 (43) (200); 2.525 (33) (022); 2.395 (29) (112) for voudourisite and 6.860 (100) (200); 6.317 (72) (111); 5.965 (84) (020); 4.512 (58) (310); 3.727 (78) (202); 3.608(82)(13$\bar 1$); 3.109 (83) (40$\bar 2$); 3.020 (50) (33$\bar 1$) for lazaridisite, respectively.

Heat-generating waste provides a number of additional technical challenges over and above those associated with the disposal of ILW. A priority area of work for Radioactive Waste Management (RWM) concerns the effect of heat on the engineered barrier system, and how this may be mitigated through the management of heat (thermal dimensioning) in a UK Geological Disposal Facility (GDF). The objective of thermal dimensioning is to provide a strategy to enable acceptable waste package loading and spatial configurations of the packages to be determined in order to enable high-heat generating waste to be successfully disposed in a GDF. An early focus of the work has been to develop a thermal modelling tool to support analyses of different combinations of package assumptions and other GDF factors, such as spacing of those packages, to assess the compliance with thermal limits. The approach has a capability to investigate quickly and efficiently the implications of a wide range of disposal concepts for the storage of spent fuel/HLW and the dimensions of a GDF. This study describes the approach taken to undertaking this work, which has included a robust appraisal of the key data (and the associated uncertainty); recent thermal dimensioning analysis has been performed to identify constraints on those disposal concepts.

Five celestine crystals were sampled from the (palaeo)surface intervening between the late Miocene to Pleistocene basaltic sequences of the Jabal Eghei (Nuqay) volcanic province in southern Libya and then characterised by applying a combination of the SEM–WDS, ICP/OES, PXRD and IR methods. Colour variations and related minerogenetic frameworks were also investigated. Three samples have greenish-blue-to-blue colour (480.4–482.5 nm), whereas the other two samples have blue–green colour (cyan; 489.1–494.1 nm). The colour purity ranges from 1.36–7.16. Their composition is similar, end-member celestine, in which only 1.6–4.1 at.% of Sr2+ content was substituted by Pb2+ (0.7–0.9 at.%), Ba2+ (0.5–0.7 at.%) and Ca2+ (0.2–0.8 at.%). Three samples contained vacancies, from 1.0 to 1.9 at.%. The content of other chemical elements is minor. The resulting unit-cell parameters have the ranges: a0 = 8.3578(9)–8.3705(6) Å; b0 = 5.3510(5)–5.3568(4) Å; c0 = 6.8683(7)–6.8767(2) Å and V0 = 307.17(5)–308.34(4) Å3. The PXRD and IR results are mainly in accordance with the SEM–WDS results, with a high level of correlation. However, a few discrepancies were found, producing several possible interpretations, the primary cause being a slight unit-cell axial anisotropy i.e. thermal expansion. As a consequence these results yield a new geothermometric tool that is based on the unit-cell axial anisotropy. The celestines investigated were formed during a Miocene intraplate volcanism with basaltic magmas, and associated brines lifted by the structural conduits (normal faults crosscutting the Sirt basin). The Sr-bearing fluids then poured into and over the faulted and fractured lagoon-type gypsum, anhydrite Eocene sediments. The celestine mineralisation formed within a ~368–430 K (~95–157°C) temperature range. The celestine formed at slightly elevated temperature and pressure conditions, close to the shallow subsurface environment (over 250 bars).

The criteria for the definition of a new mineral species currently used by the Commission on New Minerals Nomenclature and Classification (CNMNC) of the International Mineralogical Association are critically examined. In particular, the rule of the dominant constituent can violate the laws of conservation of electric charge. A series of additional rules: (1) valency-imposed double site-occupancy; (2) the dominant-valency rule; and (3) the site-total-charge approach, have been developed in an attempt to correct this error. However, none of these rules can overcome the fundamental flaw introduced by the rule of the dominant constituent, and the chemical formulae resulting from application of these rules can violate the requirements of an end-member, particularly that of electroneutrality. As a result, the IMA–CNMNC rules cannot derive end-member formulae for some groups of minerals, giving rise to many ad hoc decisions in defining distinct mineral species.

The occurrence of chloritic minerals as infillings of vesicular cavities in volcanic rocks is very common in rocks of all geological ages. Numerous chlorites have been described and analysed, but their classification and nomenclature are complicated by the fact that, as in the case with other hydrous alumino-silicates such as zeolites and clay minerals, the chloiites present a great variety of chemical compounds, usually of indefinite composition.

During 1907, a plumbiferous barytcs, deposited by a hot spring at Hokuto in Taiwan (Formosa), was discovered by Mr. Y. Okamoto. This mineral, although a special name ‘hokutolite’ was proposed for it by Professor K. Jimbō in 1912, is a variety of barytes. It shows a slight difference in its chemical composition as well gs its physical properties from ordinary barytes.

The majority of amphiboles conform to the general structural formula X2-3Y5Z8O22(OH,F,Cl)2, where X = Na, K, Ca, Y - Mg, Fe″, Mn, A1, Fe‴, Ti, and Z = Si, A1 or Ti. Two X ions occupy the positions filled by Ca in the ideal tremolite structure; the additional X ions are assumed to occur in the 'A' sites which are vacant in tremolite.

For the amphiboles, therefore, the method most commonly adopted for deriving a formula from a chemical analysis is to assume that a total of 24 anions is present in the formula unit.

Some thirty-five years or so ago small quantities of free gold were found in calcite in or near a crush-breccia filling an east and west fault, in the patch of Middle Devonian limestone which forms that portion of the coast known as Daddy Hole Plain directly south-east of Torquay. The name of the actual discoverer I have been unable to ascertain, neither do any specimens appear to have been preserved ; but the late Mr. T. Harrison, the then proprietor of the Queen's Hotel, Torquay, and several other persons subscribed about s and a small amount of prospecting work was carried out, apparently with little result. The only reference to this discovery which I know of is a brief one in 'The geology of the country around Torquay' (Mere. Geol. Survey, 1903, p. 48). To Mr. B. W. Stedham of Torquay I am indebted for the additional particulars given and also for pointing out to me the exact spot, which is on the side of a fissure formed by a large pinnacle of rock standing away from the cliff below the old quarry.

Crimsonite (IMA2014-095), PbFe3+2(PO 4)2(OH)2, the phosphate analogue of carminite, is a new mineral from the Silver Coin mine, Valmy, Iron Point district, Humboldt County, Nevada, USA, where it occurs as a low-temperature secondary mineral in association with fluorwavellite, goethite, hematite, hentschelite, plumbogummite and variscite on quartz. Crimsonite occurs in subparallel aggregates of deep red blades or plates flattened on {100} and up to 0.1 mm in maximum dimension. The streak is light purplish orange. Crystals are transparent and have adamantine lustre. The Mohs hardness is ∼3½, the tenacity is brittle, the fracture is irregular to splintery and an imperfect cleavage is likely on {101}. The calculated density is 5.180 g/cm3. Crimsonite is optically biaxial (+), with 2V = 85.5(5)° and γ – α = 0.011. Using the Gladstone-Dale relationship, the calculated indices of refraction are α = 2.021, β = 2.026 and γ = 2.032. The optical orientation is X = b; Y = a; Z = c and the pleochroism is X light orange, Y light yellow, Z red brown; Y < X < Z. Electron microprobe analyses provided PbO 40.69, CaO 0.60, ZnO 0.72, CuO 0.13, Fe2O3 23.36, Al2O3 0.34, V2O5 0.70, As2O5 12.05, P2O5 16.03, SO3 0.33 and H2O 3.64 (structure), total 98.59 wt.%. The empirical formula (based on 10 O apfu) is (Pb1.06Ca0.06)∑1.12(Fe1.71Zn0.05Al0.04Cu0.01)∑1.81(P1.32As0.61V0.05S0.02)∑2.00O8[(OH)1.64(H2O)0.36]∑2.00. Crimsonite is orthorhombic, Cccm, a = 16.2535(13), b = 7.4724(4), c = 12.1533(9) Å, V = 1476.04(17) Å3 and Z = 8. The eight strongest lines in the powder X-ray diffraction pattern are [dobs in Å(I)(hkl)]: 5.86(42)(111); 4.53(45)(112); 3.485(64)(113); 3.190(100) (022); 3.026(40)(004); 2.902(54)(511); 2.502(77)(422) and 2.268(54)(224). The structure of crimsonite (R1 = 3.57% for 740 Fo > 4σF) contains FeO6 octahedra that share edges to form dimers, which are then linked to other dimers by corner sharing to form chains along [010]. These chains are linked by PO4 tetrahedra yielding sheets parallel to {001}. The sheets are linked to one another via bonds to 8-coordinated Pb2+ atoms with non-stereoactive 6s2 lone-electron pairs.

Tlapallite is a new mineral found in 1972 at the Bambollita (La Oriental) mine near Moctezuma, Sonora. Also recently found in old specimens from Tombstone, Arizona. Data for type (Mexican) material: Colour viridian green RHS-128A with pale streak, H = 3, D calc = 5·05 g/cm3. Crystals monoclinic, class unknown. Indexing based on Ito method gave a cell: a = 11·97 Å, b = 9·11, c = 15·66, β = 90 ° 36′. Strongest lines: 11·972 Å (10), 2·985 (10), 3·540 (6), 5·946 (5), 2·887 (5), 4·731 (4), 3·372 (4), 3·282 (4). Similar data obtain for Tombstone. Chemical analysis for type material yielded the formula H6Ca2Cu3(SO4)(TeO3)4,TeO6 with Te4+:Te6+ = 4:1. However, analysis of the Tombstone material indicates a more general formula H6(Ca, Pb)2(Cu, Zn)3(SO4) (TeO3)4,TeO6. The better data from this material indicate Z = 4, D calc = 5·465 vs D meas = 5·38. Characterized by extreme birefringence, α = 1·815, β = γ = 1·960; for Tombstone α = 1·955, β = γ = 2·115.

Named from the Nahua word tlapalli, meaning paint, in allusion to its mode of occurrence at the type locality.

The thermal expansions of trimerite and beryllonite have been determined up to 800°C. No anomalies were observed in the thermal expansion curves but the expansion coefficients for beryllonite are approximately twice those of trimerite. The thermal expansion behaviour of the minerals is interpreted in terms of a tetrahedral tilting model with the main change in apparent tilting being about the monoclinic 010 plane, i.e. the 0001 pseudo-hexagonal plane.

The analysis of an acid-soluble and acid-insoluble fraction of one systematically sampled, partially dolomitized limestone bed is reported. The original lime sediment, composed principally of skeletal remains, pellets, occasional intraclasts, detrital quartz, illite, and muscovite has been modified by the addition of calcite, dolomite, and dickite cements and has been patchily replaced by dolomite, quartz, and pyrite. Rapid chemical and mineralogical variations occur over short distances, i.e. within 10 m. Fe and Mn are both present in greater concentration in dolomite than in calcite. Dolomite itself varies in overall composition within the limestones and dolostones but is always Sr-deficient. The insoluble residue is dominated by quartz. Authigenic quartz occurs but its distribution is controlled by pre-existing detrital quartz so SiO2 distribution corresponds to a detrital arrangement. TiO2 and K2O follow the distribution of SiO2 and are believed to be sited in detrital minerals, muscovite, and other unidentified minerals. Sulphur, present in pyrite, has a patchy distribution but is deficient in totally dolomitized areas suggesting removal of pyrite during dolomitization.