The specimen to be described was found in 1925 by Miss H. K. Cargill and Miss J. A. Ledeboer on a scree slope beneath a gully in the basaltic capping of the Slaufrudal granite-granophyre stock at Kvosafoss, SE. Iceland. Unfortunately the rock was not discovered in situ, but it must belong to the upper part of the stock or a dike apophysis of it. An examination of the rock was begun by Miss Ledeboer, but she was unable to continue the work; I am indebted to her for the photographs of pl. VII, figs. 1 and 2.

During the examination of the basalts of Calciferous Sandstone age which are mapped on the one-inch Sheet 23 (Hamilton, Lanarkshire) Scotland, the peculiarities of zoning exhibited by the porphyritic felspar were studied in some detail. As only a summary of the details is possible in the memoir explanatory of the geology of this Sheet, the description of the zoning is offered here, and some conclusions regarding the magmatic history of the zoned felspars are presented.

An accurate and highly sensitive method for the measurement of reflectivities incorporating a photomultiplier and a direct-reading galvanometer is described. The high sensitivity of the technique permits the determination of spectral reflectivities as opposed to ‘white’ light reflectivities, the latter values being subject to variation according to the type of apparatus used in their determination. The absolute spectral reflectivities of pyrite determined by the method are in good agreement with those quoted by some previous workers. Spectral reflectivities in air and oil and refractive and absorption indices are given for wavelengths from 430–650 mµ for manganese oxide minerals.

Several restricted outcrops of potash-rich volcanic rocks occur in the Spanish provinces of Murcia and Almeria, where they form intrusive pitchstones or surface lavas among country rocks consisting of Tertiary and Quaternary sediments: the volcanic rocks include jumillites and verites from the type localities of Jumilla and Vera and it is these rocks that have been investigated. Jumillites are basic lavas, sometimes coarse-grained, rich in MgO, CaO, K2O, TiO2, and P2O8, poor in SiO2, Al2O3, and Na2O and they contain important, if minor, concentrations of Cr2O3, BaO, SrO, and ZrO2. Their mineralogy is distinctive: chrome diopside, forsterite, titaniferous phlogopite, kataphorite, and sanidine, with rare leucite. Verites, typically, are black pitchstones or pitchstone breccias that range from basic to acid in composition ; they are more variable in their chemistry than jumillites, but in part this variation might be due to introduction of silicate and carbonate into some of the verites during extensive hydrothermal alteration, which has undoubtedly affected their initial chemistry. Mineralogically, verites are simpler than jumillites and have fewer phenocrysts: forsterite, some diopside, phlogopite, and, occasionally, leucite. Certain mineralogical and compositional similarities of jumillites and verites suggest they may have originated from the same type of parental magma. Their mineralogy and chemistry also relate the jumillites and verites to phlogopite-bearing potash-rich volcanics from East Africa, America, and Australia and it seems possible that all these rocks might have a common parent in mica peridotite or mica pyroxenite.

The problem of magnesian pyroxenes in acid liquids is considered in the light of new analyses of pyroxene and magnetite phenocrysts. It is suggested that the early precipitation of titaniferous magnetite, which will strongly deplete the liquid in iron, will decrease the iron:magnesium ratio of the pyroxene components in the liquid. Accordingly the iron:magnesium ratio of a pyroxene precipitating from an acid liquid may vary over a wide range depending upon the presence or amount of early magnetite.

Heklaite, with the ideal formula KNaSiF6, was found among fumarolic encrustations collected in 1992 on the Hekla volcano, Iceland. Heklaite forms a fine-grained mass of micron- to sub-micron-sized crystals intimately associated with malladrite, hieratite and ralstonite. The mineral is colourless, transparent, non-fluorescent, has a vitreous lustre and a white streak. The calculated density is 2.69 g cm–3. An SEM-EDS quantitative chemical analysis shows the following range of concentrations (wt.%): Na 11.61–12.74 (average 11.98), K 17.02–18.97 (average 18.29), Si 13.48 –14.17 (average 13.91), F 54.88–56.19 (average 55.66). The empirical chemical formula, calculated on the basis of 9 a.p.f.u., is Na1.07K0.96Si1.01F5.97. X-ray powder diffraction indicates that heklaite is orthorhombic, space group Pnma, with the following unit-cell parameters: a = 9.3387(7) Å, b = 5.5032(4) Å, c = 9.7957(8) Å , V = 503.43(7) Å3, Z = 4. The eight strongest reflections in the powder diffraction pattern [d in Å (I/I0) (hkl)] are: 4.33 (53) (102); 4.26 (56) (111); 3.40 (49) (112); 3.37 (47) (202); 3.34 (100) (211); 2.251 (27) (303); 2.050 (52) (123); 2.016 (29) (321). On the basis of chemical analyses and X-ray data, heklaite corresponds to the synthetic compound KNaSiF6. The name is for the type locality, the Hekla volcano, Iceland.

Banded sphalerite from Bleiberg, Austria, contains ubiquitous relics of Fe-thiosulphates and Fesulphites up to 50 μm in size. Zn, Pb, Ni and As form admixtures ranging from a few to 12 wt.% in these compounds. It is suggested that banded sphalerite is formed by a replacement of banded thiosulphate and thiosulphite precursors. This suggestion is supported by a significant admixture of Fe 0.41-8.20 wt.%) and the presence of goethite inclusions in banded sphalerite. In contrast, crystalline ZnS intergrown with the banded variety is Ni-free and contains only 0.06-0.14 wt.% Fe.

Banded pyrite contains inclusions of Fe-thiosulphate up to 200 μm in size. These thiosulphates contain (wt.%): 0.09-1.92 Zn, and 2.67−4.02 Pb. Pyrite formed by replacement (breakdown) of Fethiosulphate precursors contains 3.69-3.83 wt.% Pb.

It is suggested that banded sulphides precipitate from solutions carrying sulphur with mixed valances, and crystalline sulphides grow from solutions where the dominant dissolved sulphur is in the form of sulphidic anions.

Mercury has been determined by radiochemical neutron-activation analysis in nineteen representative rocks from the Skaergaard intrusion and in the separated cumulus minerals of five. The chilled marginal gabbro contains 0.23 ppm Hg, values in the Layered Series rocks ranging from 0.07 to 0.34 ppm, in one exceptional case reaching 1.23 ppm Hg. There is a tendency for mercury to be more abundant in leucocratic than in average or melanocratic rocks at a similar horizon. Somewhat higher levels of mercury are found in the granophyric rocks at the top of the intrusion.

Apart from a weak and sporadic tendency to be preferentially enriched in plagioclase, the distribution of mercury between the various cumulus phases is fairly uniform and it is thought to occur as uncharged atoms mainly occupying spaces resulting from lattice defects and imperfections rather than in specific structural sites.

The distribution pattern of mercury in the intrusion appears to be determined by its high volatility and chemical inertness; no real evidence of any chalcophile character is observed.

Haláp Hill is an eroded remnant of young (∼3 Ma) alkaline basalt in the western part of the Bakony–Balaton Highland Volcanic Field, Tapolca, Hungary. Cavities in the basalt contain miarolitic minerals (augite, apatite, magnetite, plagioclase and sanidine), zeolites (analcime, chabazite-Ca, chabazite-Na, garronite, gismondine, gmelinite-Ca, gmelinite-Na, gobbinsite, gonnardite-Na, natrolite, mesolite, phillipsite-Ca, phillipsite-K, phillipsite-Na and scolecite) and other secondary minerals (calcite, smectite-group minerals, goethite and Mn-oxides). Chabazite-Na, gmelinite-Ca, gonnardite-Na, phillipsite-Na and phillipsite-K are reported from Haláp Hill for the first time. The Ca-rich and Na-rich zeolites and abundant calcite were produced by hydrothermal alteration. Mineral assemblages were characterized by X-ray diffraction, differential thermal analysis, energy-dispersive spectrometry and wavelength-dispersive spectrometry. The secondary mineral assemblages were probably formed as a result of low-temperature hydrothermal activity at 50—100°C. Miarolitic minerals crystallized first in cavities in the basalt; they were followed by zeolite-group minerals and calcite. Analcime and phillipsite with or without chabazite/gmelinite/garronite or gobbinsite were the first zeolite-group minerals to crystallize; gonnardite-Na and natrolite crystallized later from Na-rich fluids. Calcite and smectite-group minerals crystallized continually. This paragenetic sequence is similar to others which have been reported in basalt from other localities in the Balaton Highland, Iceland and Northern Ireland.

Eocene tholeiitic basalts occur throughout the length of New Caledonia where their emplacement preceded that of the peridotite massifs. In the south, two areas of basaltic rocks are intimately associated with Eocene sediments, which have been overridden by the peridotites. The aphyric, holocrystalline basalts consist of plagioclase, clinopyroxene, titanomagnetite, and minor quartz together with their abundant alteration products, which include epidote and uralite. The chemical compositions of these rocks fail to show agreement with oceanic tholeiitites, as suggested by earlier writers, although strong similarities exist with the basalts of the Papuan Ultramafic Belt.

Vincentite, a new palladium mineral containing As, Sb, and Te, has been discovered in platinum-gold concentrates from the Riam Kanan River, SE. Borneo. It occurs as small grains (up to 40 µm) in iron-bearing platinum. In reflected light, vincentite is light brownish-grey and in some sections weakly anisotropic. Reflectance at 470, 546, 589, and 650 nm is 46·3–47·5, 49·2–52·8, 51·7–53·9, and 54·9–56·0, respectively. VHN15 = 494. Electron probe analysis has been performed on two grains, the compositions of which are (Pd5·32Pt0·68) (As0·90Sb0·48Te0·65) and (Pd5·17Pt0·83) (As0·89Sb0·70Te0·45) or, simplified, (Pd,Pt)3(As,Sb,Te). This is distinctly different from both arsenopalladinite, Pd5(As,Sb)2 with As > Sb as defined by Clark (1974), and mertieite, Pd5(Sb,As)2.

The following lines have been observed in the powder pattern: 4·180, 3·950, 3·240, 2·750, 1·997, 1·749, 0·944. This cannot be matched by the patterns of arsenopalladinite, mertieite, isomertieite, stibiopalladinite, atheneïte, or synthetic Pd3As.

The name is in honour of Prof. E. A. Vincent, of Oxford.

The new mineral greenlizardite (IMA2017-001), (NH4)Na(UO2)2(SO4)2(OH)2·4H2O, was found in the Green Lizard mine, Red Canyon, San Juan County, Utah, USA, where it occurs as a secondary alteration phase. It is associated with ammoniozippeite, boussingaultite and dickite. It forms as light green-yellow blades up to ~0.3 mm long. The mineral is vitreous and transparent with a white streak. It fluoresces greenish blue in 405 nm light. Mohs hardness is ~2. Crystals are brittle with irregular fracture and two cleavages: perfect {001} and good {2$\bar 1$0}. Greenlizardite is easily soluble in room-temperature H2O. The calculated density is 3.469 g cm–3. Optically, it is biaxial (+) with α = 1.559(1), β = 1.582(1) and γ = 1.608(1) (measured in white light). The measured 2V is 88(1)°; the calculated 2V is 87.8°. Dispersion is moderate, r < v. Pleochroism is X = very pale yellow green, Y = pale yellow green and Z = light yellow green; X < Y < Z. The optical orientation is X ≈ c, Y ≈ a and Z ≈ b*. The Raman spectrum exhibits bands attributable to both sulfate and uranyl groups. Electron probe microanalyses (with H2O based on the crystal structure) yielded (NH4)0.98Na1.00U1.96S2.04O18.00H10.02. Greenlizardite is triclinic, P$\bar 1$, a = 6.83617(17), b = 9.5127(3), c = 13.8979(10) Å, α = 98.636(7), β = 93.713(7), γ = 110.102(8)°, V = 832.49(8) Å3 and Z = 2. The crystal structure (R1 = 2.39% for 2542 I > 2σI) contains edge-sharing dimers of UO7 pentagonal bipyramids. The dimers link by sharing corners with SO4 groups to form a [(UO2)2(SO4)2(OH)2]2– sheet based on the phosphuranylite anion topology. Zig-zag edge-sharing chains of NaO6 octahedra link adjacent [(UO2)2(SO4)2(OH)2]2– sheets, forming thick slabs. NH4 bonds to O atoms in adjacent slabs linking them together. H2O groups occupy channels in the slabs and space between the slabs.

U-enriched granites occur in a Precambrian window in the Caledonides of central Sweden and intrude an extensive supracrustal formation dominated by acid terrestrial volcanics. During the Caledonian orogeny, thrusting, foliation, mylonites, and mesoscopic folds developed in the Precambrian rocks under low-grade metamorphic conditions. Ground and airborne γ-spectrometry indicate U-enrichment mainly in the northern part of the window where two uraniferous granites have been intruded. Several small U vein-type mineralizations are associated with one of the granites. The largest occurrence of the mineralization might be economic, and a Rb-Sr age determination has established a minimum age of 1500 Ma on the associated granite which is highly evolved.

Naldrettite, Pd2Sb, is a new intermetallic mineral discovered in the Mesamax Northwest deposit, Cape Smith fold belt, Ungava region, northern Québec. It is associated with monoclinic pyrrhotite, pentlandite, chalcopyrite, galena, sphalerite, cobaltite, clinochlore, magnetite, sudburyite (PdSb), electrum and altaite. Other rarer associated minerals include a second new mineral (ungavaite, Pd4Sb3), sperrylite (PtAs2), michenerite (PdBiTe), petzite (Ag3AuTe4) and hessite (Ag2Te). Naldrettite occurs as anhedral grains, which are commonly attached or moulded to sulphide minerals, and also associated with clinochlore. Grains of naldrettite vary in size (equivalent circle diameter) from ~10 to 239 μm, with an average of 74.4 mm (n = 632). Cleavage was not observed and fracture is irregular. The mineral has a mean micro-indentation hardness of 393 kg/mm2. It is distinctly anisotropic, non-pleochroic, has weak bireflectance, and does not exhibit discernible internal reflections. Some grains display evidence of strain-induced polysynthetic twinning. Naldrettite appears bright creamy white in association with pentlandite, pyrrhotite, clinochlore and chalcopyrite. Reflectance values in air (and in oil) for R1 and R2 are: 49.0, 50.9 (35.9, 37.6) at 470 nm, 53.2, 55.1 (40.3, 42.1) at 546 nm, 55.4, 57.5 (42.5, 44.3) at 589 nm and 58.5, 60.1 (45.4, 47.2) at 650 nm. The average of 69 electron-microprobe analyses on 19 particles gives: Pd 63.49, Fe 0.11, Sb 35.75, As 0.31, and S 0.02, total 99.68 wt.%, corresponding to (Pd1.995Fe0.007)2.002(Sb0.982AS0.014S0.002)0.998. The mineral is orthorhombic, space group Cmc21, a 3.3906(1), b 17.5551(5), c 6.957(2) Å , V 414.097(3) Å3, Z = 8. Dcalc is 10.694(1) g/cm3. The six strongest lines in the X-ray powder-diffraction pattern [d in Å (I)(hkl)] are: 2.2454(100)(132), 2.0567(52)(043), 2.0009(40)(152), 1.2842(42)(115), 1.2122(50)(204) and 0.8584(56)(1.17.4).

Forty-three natural alkali feldspars have been homogenized and used to correlate with wt % K2O. The regression of Or on is Or (wt %) = 465·5 (Å)-1877·5, and is comparable to that obtained on an exchanged orthoclase (Wright, 1968). A deviation from the Orville (1963, 1967) determinative line for synthetic sanidine-albite is greatest at the high potassium end of the series. The discrepancy is not caused by failure to homogenize or incomplete disorder. The presence of cations other than potassium and sodium, or cation deficiency, or both cannot be discounted as a cause.

X-ray spectromicroscopy is a powerful tool for addressing key questions in the environmental sciences due to its high spectral and spatial resolution. It has been used successfully for material research, biology and environmental studies, e.g. in the form of μ-X-ray fluorescence and spectromicroscopy with a spatial resolution of <100 nm. With the combination of high-resolution microscopy and spectroscopy it is possible to determine elemental composition as well as chemical speciation, and also identify trace elements to nm-resolution. Samples from soils and groundwater aquifers have been imaged to visualize the appearance of structures on the nm- and μm-scale. The effectof changing chemical conditions in an aqueous environment on the appearance of these structures has been imaged and evaluated. Clay dispersions, microhabitats and morphological effects of biologically-induced redox changes of humic substances have been imaged tomographically, conveying a detailed threedimensional presentation of the specimen structure. Using the spectromicroscopy potential, the distribution of organic and inorganic components, as well as different inorganic components, has been studied. Spectra were analysed for major chemical constituents and were used, for example, to assess differentsulphur species in an entire soil profile.

Samples from Russia and Scotland are used to examine the interaction of the REE-Ti silicate chevkinite-(Ce) with hydrothermal fluids. Altered zones in crystals are distinguished by using areas of low intensity on backscattered-electron images, low analytical totals, increasingly large departures from stoichiometry and, in some cases, the presence of micropores. Initial alteration of the chevkinite results in strong Ca enrichment. With increasing degrees of alteration, Ca abundances drop sharply, as do those of the REE, Fe and Si. In contrast, Ti levels increase strongly, usually accompanied by higher Nb ± Th levels. The most altered zones contain up to 36 wt.% TiO2 and the formula cannot be expressed in the standard chevkinite formula. In detail, samples follow different alteration trends, presumably reflecting different P, T, fO2 and fluid composition. The Ti enrichment may have been related to a reaction front of dissolution-reprecipitation passing through the outer zones of the original chevkinite, leaving behind a reprecipitated Ti-enriched phase which may or may not be chevkinite.

Metasediments of the Tayvallich Subgroup of the Dalradian at Kinnairds Head, Fraserburgh are metamorphosed to sillimanite + K-feldspar grade and form part of the classic high-T low-P Buchan metamorphic terrain. Pelitic samples constrain peak-metamorphic conditions to 615±13°C and 2.2±0.2 kbar. At or close to the metamorphic peak, irregular garnetiferous aplites and autopegmatite bodies intruded the metasediments. Thin marble bands within the sequence are dominated by calcite with diopside, and equilibrated with relatively CO2-rich, internally buffered fluids. Where these are in close proximity to granitoid pegmatites, wollastonite dominates the matrix, and fractures and veins running through the rock contain concentrations of grossular and vesuvianite. With increasing distance from the pegmatite, vesuvianite and then grossular disappear, and wollastonite is only patchily developed. Such occurrences require a flushing of the marble by metasomatic (siliceous and aluminous) aqueous fluids which were derived from the de-watering of the adjacent pegmatite as it crystallized. The large quantities of dissolved silica led to pervasive wollastonite formation for several metres. The smaller quantities of Al reacted to form Ca-Al-silicates which were confined to the fractures.