Calzirtite, essentially CaTiZr3O9, has been identified in residual soils from the Bukusu carbonatite complex in Uganda. A satisfactory ultrasonic technique was developed for cleaning the samples prior to studying their mineralogy. Other heavy minerals present include ilmenite, perovskite, melanite, apatite, zircon, and baddeleyite. The properties and composition of calzirtite are compared with the available data from occurrences in the U.S.S.R. The mineral has a metasomatic paragenesis and probably indicates the presence of carbonatized rocks at depth.

We are apt to regard selenite or transparent gypsum as a useless mineral, apart from the very small quantity used in plates for microscope work. It is the object of this paper to show that from the first, to at any rate the seventeenth century in Europe and to the first half of the nineteenth in South America, considerable use was made of it. For the classical period the argument is based upon the identification of lapis specularis as mainly, if not entirely, selenite. Most translators render the name as talc or mica, the first word probably a vulgar error for the second, while some admit gypsum to have been included; Bailey in his notes on Pliny considers that two passages suggest gypsum but gives the preference to mica, while Zeitler claims nearly all the passages referred to below for this mineral. Pliny is, of course, our chief authority: I give the relevant passages in Philemon Holland's translation as more in keeping with the greater part of this paper, adding notes and the original Latin where necessary.

The synthetic analogue of mineral stillwaterite, Pd8As3, was synthesised and its crystal structure was solved to R1 = 0.0341 based on single crystal X-ray diffraction data. Pd8As3 is trigonal and the space group is P$\bar{3}$. The unit-cell parameters are a = 7.4261(4), c = 10.3097(9) Å and V = 492.38(7) Å3 with Z = 3. The structure builds up by layers of Pd and As atoms. Pd-nets and As-nets are parallel to (110) and stack along the c axis direction. The stacking sequence is ABCDEEDCBA. The relation between structures of minerals with the common formula Pd8T3 (T = As or/and Sb) are discussed. They are formed by nets of pnictogen and palladium atoms. The common feature of the structures is 36 topology of pnictogen nets. The differences are stacking sequences and topology of the palladium nets.

It is possible with a standard Geoscan microanalyser to produce back-scattered electron pictures that resemble Kikuchi patterns but which are produced by a different mechanism. These effects have been called scanning electron beam anomalous transmission (SEBAT) patterns and they are produced by the interaction of a parallel scanning beam of high-energy electrons with a crystalline sample. The patterns are excellent indicators of the crystallographic perfection and orientation of samples and can provide information about the lattice dimensions of solid, bulk specimens. The same specimens can, if necessary, be chemically analysed in the same instrument.

In order to produce the patterns the electron beam must be deflected through a minimum angle of approximately 20° and, on existing instruments, the beam covers an area of about 2 × 2 mm during such a deflection. Minor modification of the authors' microanalyser has reduced the scanned area to 0·5 × 0·5 mm and attempts are being made to reduce this even further.

In favourable circumstances the technique enables the mineralogist to determine, rapidly and easily, the crystallographic structure and orientation of large, bulk specimens. Examples are given of patterns that have been produced from cleaved, as grown, and polished mineral faces. The degree and nature of the crystallographic damage produced during mechanical polishing of a galena crystal are illustrated.

Ammonioleucite, (NH4)[AlSi2O6], and its deuterated analogue ND4-ammonioleucite (ND4)[AlSi2O6] have been synthesized in 20–150 mg amounts at 300°C and 500 MPa in 5 mm wide, 4 cm long Au capsules using Rene’ metal hydrothermal autoclaves. The resultant product consists of 20–30 mm-size single tetragonal crystals as well as 50 –100 mm wide clumps of ingrown crystals. Infrared (IR) spectra obtained from powdered samples are assigned on the basis of Td symmetry for both the ammonium and deutero-ammoniumion. They show triply degenerate vibrational bands (i.e. v3 and v4), some overtones, and combination modes from NH4+ and ND4+. While Td symmetry for NH4+ in ammonioleucite is not strictly correct due to distortion of the NH+4 molecule, the non-cubic field is not large enough at room temperature to cause a substantial splitting in the bands. However, this perturbation is documented in the IR spectra by a substantial increase in the FWHH as well as the occurrence of shoulders on the broadened bands. In contrast, at lower temperatures, the observed band splittings in the former triply degenerated states of v3 and v4 could be explained by an effective local field with D2 symmetry.

Rietveld refinement indicates that ammonioleucite, like leucite, has a tetragonal structure with space group symmetry I41/a. Here the NH4+ molecule replaces the K+ cation on the 8-fold co-ordinated W site, which has m symmetry. Substitution of NH4+ for K+ in the leucite structure results in an increase of the cell parameter a, whereas c is slightly reduced. The mean <W–O> bond length of ammonioleucite is increased in comparison to leucite from 3.00 to 3.12 Å whereas the mean <T–O> bond length of 1.65 Å remains unchanged. This results in an increase in the volume of the polyhedron hosting the NH4+ molecule as well as a decrease in distortion for structural channels parallel to the <111> direction, formed by the arrangement of the six-fold rings, on which the W cations are located. The same effect is also observed, in general, when Rb+ or Cs+ is substituted for K+ in leucite.

Amphibole in the Larvik alkaline plutonic complex in the Oslo rift, Norway, has Ti-rich compositions from edenite through pargasite to kaersutite, and has a large H+ deficiency (0.7–1.1 atoms per formula unit: a.p.f.u.) with a large oxy component in the amphibole OH– site (O2– = 2 – (OH + F + Cl) = 0.2–0.9 a.p.f.u.), similar to the mantle-derived kaersutites. Their compositions reveal a characteristically low Fe3+/(Fe3++Fe2+) ratio (<0.23) and a high F concentration (0.3–0.9 a.p.f.u.). Correlation with the Fe3+ ratio caused by Fe2+ + OH– = Fe3+ + O2– + 1/2H2 substitution is negligible, which is supported by H and O isotope compositions. A possible substitution, [6]Al3+ + OH– = [6]Ti4+ + O2– may be operative for Larvik kaersutites when the O2–/Ti is 1.0. A relatively larger O2–/Ti ratio (1.2—2.0) suggests an another kaersutite substitution mechanism, [6]R2+ + 2OH– = [6]Ti4+ + 2O2–, where [6]R2+ = Fe2+ + Mg + Mn. These effects might result in the limited O2–/Ti ratio value from 1.0 to 2.0.

A negative correlation between Ti and F, suggesting F incorporation into kaersutite may diminish the O2–/Ti ratio, not only due to the occupation of this non-oxy species in the O3 site, but also due to F—Ti avoidance. Composition-dependent H and O isotope variations (δD = –106 to –71% and δ18O = 4.6–5.2%) suggest equilibrium in the closed-system magma with differentiation. The mineral chemistry of Larvik oxy-kaersutitic amphibole could reflect the crystallization in a closed-system magma during rifting with passive crustal thinning at the Oslo palaeorift.

The new alluaudite-group mineral khrenovite with the ideal, end-member formula Na3Fe3+2(AsO4)3 was found in the Arsenatnaya fumarole, Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with aphthitalite-group sulfates, badalovite, calciojohillerite, nickenichite, johillerite, tilasite, svabite, achyrophanite, ozerovaite, pansnerite, arsenatrotitanite, anhydrite, sanidine, hematite, cassiterite, rutile and pseudobrookite. Khrenovite occurs as coarse prismatic crystals up to 0.2 × 0.3 × 0.8 mm and their clusters up to 1 mm across. It is transparent, honey-coloured, red-, orange- or yellow-brown, with vitreous lustre. Khrenovite is brittle, cleavage was not observed. Dcalc is 4.257 g cm–3. Khrenovite is optically biaxial (+), α = 1.825(7), β = 1.834(7), γ = 1.845(7) and 2Vmeas. = 80(10)°. The chemical composition (wt.%, electron-microprobe) is: Na2O 11.47, K2O 1.23, CaO 0.18, MgO 0.01, MnO 4.10, CuO 4.27, ZnO 1.99, Al2O3 0.17, Fe2O3 21.12, SiO2 0.08, P2O5 0.01, V2O5 0.10, As2O5 56.03, SO3 0.02, total 100.78. The empirical formula calculated on the basis of 12 O apfu is (Na2.26K0.16Ca0.02Mn0.35Cu0.33Zn0.15Al0.02Fe3+1.62)Σ4.91(As2.98Si0.01V0.01)Σ3.00O12. Khrenovite is monoclinic, C2/c, a = 12.2394(7), b = 12.7967(5), c = 6.6589(4) Å, β = 112.953(7)°, V = 960.37(10) Å3 and Z = 4. The crystal structure was solved from single-crystal X-ray diffraction data with R1 = 0.0287. Khrenovite is isostructural with other alluaudite-group minerals. Its structural formula simplified to the species-defining constituents is A(1)NaA(2)’NaM(1)NaM(2)Fe3+2(TAsO4)3. The mineral is named in honour of the Russian volcanologist and geologist Anatoly Petrovich Khrenov (1946–2016).

Amphiboles of the tremolite-ferro-actinolite series from the Bergslagen district in central Sweden have between 0 and 46% of their M1-M3 sites occupied by Mn. These amphiboles are divided into two groups; (1) a group characterised by Mn (M1-M3) > (Mg or Fe) (M1-M3), and (2) a group with much lower contents of Mn (M1-M3), showing the following chemical characteristics: (a) Mn (M1-M3) never exceeds Fe (M1-M3); (b) in Mg-rich members of the group [Mg (M1-M3) > (Mn or Fe) (M1- M3)], the highest amounts of Mn (M1-M3) occur in amphiboles with about 2.20 Mg (M1-M3) per formula unit (pfu); in Fe-rich members of the group Fe [(M1-M3) > (Mg or Mn) (M1-M3)] high amounts of Mn (M1-M3) [> 0.4 Mn (MI-M3)] pfu only occur in amphiboles with >3.40 Fe (M1-M3) pfu; (d) the lowest amounts of Mn (M1-M3) occur in amphiboles with Mg (M1-M3) = Fe (M1-M3).

Mn (M4) increases with increasing amounts of Mn (M1-M3), indicating that solid solution towards the tirodite-dannemorite series is enhanced by incorporation of Mn (M1-M3).

This paper presents a literature survey of compositions of the fibrous zeolites mesolite, natrolite, thomsonite and their derivatives such as pseudomesolite, high-Na mesolite, tetranatrolite, paranatrolite, ranite, and gonnardite, and evaluates them in the light of new electron probe analyses and X-ray powder data for gonnardites and associated minerals from Aci Castello, Gignat, Hills Port, Kladno, and Lamo. The analyses are plotted on the basis of bivalent vs. trivalent cations per 80 oxygen cell and a new chemical classification is tentatively proposed. It is concluded that ranite is definitely not synonymous with gonnardite and until species status is confirmed it is useful to retain this term as a Ca- and Al-rich disordered variety of natrolite. It is further concluded that natrolite and tetranatrolite contain up to 2 Ca, ranite 2–4 Ca, gonnardite 4–6 Ca and thomsonite 6–8 Ca atoms with corresponding limits on the Al atoms. Compositions are governed by NaSi = CaAl and to some extent by Na2 = Ca type replacements and the Al-content generally varies sympathetically with Ca-content. The plot reveals that most high-Na mesolites are ranites, a number of gonnardites are ranites and one or two are tetranatrolites. The compositional field of gonnardite crosses that of mesolite (and pseudomesolite), but these minerals can be easily distinguished optically and by their powder patterns. The unit cell volumes increase in the order tetranatrolite, ranite, gonnardite and paranatrolite, therefore if the 1040 (or 1460) line can be identified in the powder patterns one can distinguish between these minerals. New infrared spectra of gonnardite, ranite and tetranatrolite are compared with each other and with published spectra, and differences are noted. DSC results for gonnardite and ranite are compared and appear to be diagnostic.

The Loch Shin monzogranite is host to quartz veins bearing the sulphosalts aikinite, hammarite, lindströmite, krupkaite, gladite and pekoite, which belong to the aikinite-bismuthinite series, and represents the first significant occurrence of this series in the United Kingdom. Inclusions of the sulphotelluride tetradymite occur in krupkaite-gladite. Berryite is present as inclusions in chalcopyrite. Electron microprobe analyses reveal a range of compositions in individual crystal masses from hammarite to krupkaite in one sample, and from krupkaite to gladite in a second. Compositions between friedrichite and hammarite and gladite and pekoite are notably absent.

Emerald green chromian 2M1 mica occurs in metamorphosed and metasomatized limestones, related to serpentinic rocks from Sierra Nevada, Spain. Chemical analysis gave: SiO2 44.51, Al2O3 27.60, TiO2 0.17, Cr2O3 3.35, Fe2O3 1.76, FeO 0.07, MnO 0.00, MgO 8.59, Li2O 0.03, Rb2O 0.01, BaO 0.01, CaO 1.71, Na2O 0.40, K2O 7.86, H2O 4.21 = 100.28. Optic properties are: pleochroism X blue, Y green, Z bluish green; refractive indices: α=1.562, β=1.611, γ=1.616 (yellow light); inclined dispersion, r > v. Orientation: second order mica. Refined parameters are a = 5.2116(6), b = 9.045(2), c = 19.97(2)Å, β = 95.7(3)°. The structure is discussed and an order in the octahedral M(1) sites is observed, but no ordering in the tetrahedral T(1) and T(2) cations is detected. The mica described is a mariposite with anoma-lously high contents of Ca and Mg.

The new mineral uranoclite (IMA2020-074), (UO2)2(OH)2Cl2(H2O)4, was found in the Blue Lizard mine, San Juan County, Utah, USA, where it occurs as tightly intergrown aggregates of irregular yellow crystals in a secondary assemblage with gypsum. The streak is very pale yellow and the fluorescence is bright green–white under 405 nm ultraviolet light. Crystals are translucent with vitreous lustre. The tenacity is brittle, the Mohs hardness is ~1½, the fracture is irregular. The mineral is soluble in H2O and has a calculated density of 4.038 g⋅cm–3. Electron microprobe analyses provided (UO2)2(OH)2.19Cl1.81(H2O)4. The six strongest powder X-ray diffraction lines are [dobs Å(I)(hkl)]: 8.85(38)(002), 5.340(100)(200, 110), 5.051(63)($\bar{2}$02), 4.421(83)(112, 004, 202), 3.781(38)($\bar{2}$12) and 3.586(57)(014, $\bar{2}$04). Uranoclite is monoclinic, P21/n, a = 10.763(8), b = 6.156(8), c = 17.798(8) Å, β = 95.656(15)°, V = 1173.5(18) Å3 and Z = 4. The structure is the same as that of synthetic (UO2)2(OH)2Cl2(H2O)4 in which the structural unit is a dimer consisting of two pentagonal bipyramids that share an equatorial OH–OH edge. The dimers are linked to one another only by hydrogen bonding. This is the second known uranyl mineral containing essential Cl and the first in which Cl coordinates to U6+.

Golden perch (Macquaria ambigua) is a freshwater game-fish native to central and southeast Australia. Larvae of this fish species were used in two different types of experiments to evaluate the effects of short-term exposures (up to 6 days) to aqueous gold, 5 nm gold nanoparticles (AuNPs), or 50 nm AuNPs. Relative to the control, increased gold concentrations corresponded with yolk-sac edema (swelling). Larvae exposed to 50 μM of 5 nm AuNPs had yolk-sacs that were ~1.5 times larger resulting in the appearance of bent notochords. After two days of exposure, 100% mortality was observed. Total mortalities were <25% in the other larvae–gold systems, suggesting that these larvae can quickly adapt to the presence of gold. In terms of an oxidative stress response, the larvae from all systems did not express high enzymatic activity. The state of the gold determined how much could be taken up (or immobilised) by a larva. Aqueous gold and 5 nm AuNPs easily pass through cells; therefore, larvae exposed to these forms of gold contained the highest concentrations. Scanning electron microscopy confirmed that cells comprising the epithelium and fins contained AuNPs. Aqueous gold was reduced to nanometre-scale particles within cells. Comparatively, 5 nm AuNPs appeared to be aggregated within cells forming clusters hundreds of nanometres in size. On the contrary, 50 nm AuNPs were not observed within cells but were detected within larvae by (single particle) inductively coupled plasma mass spectroscopy, suggesting that these AuNPs were probably taken up through the mouth or gills. The results of the present study demonstrate that exposure to AuNPs had adverse effects on developing golden perch larvae. Additionally, these effects were dependent on the size of the AuNPs.