Thirty pyrite samples from a wide range of localities were analysed using relative comparator and k0 neutron activation analysis (NAA) techniques at the University of Missouri Research Reactor, Columbia, Missouri, USA (MURR) and the Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, Australia (ANSTO), respectively. Statistical analyses of the trace-element data produced by the two methods showed a generally good correlation, with the majority of elemental concentrations of paired data reported by MURR and ANSTO being indistinguishable at a 0.05 significance level. Trace-element analyses of pyrite from Navajún in Spain by both techniques compare well with published data. There is evidence for contamination by Al, Na and Ti in one set of samples, this is likely to have been introduced by contact with a plastic used in sample preparation.

A rare earth element (REE)-, Cr- and Mg-bearing variety of the vanadium epidote-group mineral mukhinite occurs in a calcite–dolomite carbonatite dyke cutting metamorphosed volcano-sedimentary rocks exposed in the walls of the quarry of the Svetlinsky gold deposit, South Urals. This mineral was found in a paragene assemblage including native sulphur, phlogopite and fluorophlogopite, together with accessory pyrite, other sulfides and sulfosalts, gold, Cr- and V-bearing muscovite, margarite, Cr- and V-bearing dravite, fluoro-tremolite, actinolite, fluoro-pargasite, anhydrite, apatite, uranium hydroxides, V-rich titanite, V- and Nb-rich rutile, spinel and corundum. The contents of ΣREE2O3 and V2O3 in mukhinite vary in the ranges of 4.01–9.69 and 5.34–7.46 wt.%, respectively. A Raman spectrum of REE-rich mukhinite is provided. The main schemes of isomorphic substitutions in mukhinite are ΣREE + Mg ↔ Ca + Al and V+Cr ↔ Al. The crystal structure of REE-rich mukhinite has been studied by single-crystal X-ray diffraction analysis. The mineral is monoclinic, with the space group P21/m, and unit-cell parameters are: a = 8.8972(11) Å, b = 5.6221(6) Å, c = 10.1519(12) Å, β = 115.169° and V = 459.60(11) Å3. The crystal structure of REE-rich mukhinite is similar to that of its synthetic analogue; the refined crystal-chemical formula of the sample studied is (Z = 2): {A1CaA2(Ca0.8REE0.2)}{M1(Al0.95Cr0.05)M2AlM3[(V,Cr)3+0.40Al0.35Mg0.25]}(Si2O7)(SiO4)O(OH).

The paper presents detailed mineralogical and structural characteristics of novograblenovite that occurs abundantly on a burning coal dump at Radlin, Upper Silesia, Poland. Our results indicate that NH4MgCl3⋅6H2O is the proper formula of this mineral. The thermal behaviour of novograblenovite shows a two-step dehydration at 155 and 193°C and sublimation of NH4Cl at 341°C. A Raman spectrum, obtained for the first time, reveals the normal modes of H2O and NH4+ vibrations. The crystal structure of novograblenovite was refined on the basis of high quality X-ray diffraction data. The final discrepancy factor wR2 was 0.0567 for 94 parameters and 1464 independent reflections. The structure has a monoclinic C2/c space group symmetry with the following unit cell parameters: a = 9.2709(3) Å, b = 9.5361(2) Å, c = 13.2741(4) Å and β = 90.054(3)°. We were able to specify the architecture of the disordered NH4+ cation located at the symmetry centre. This led to reasonable parameters for the H-bonding formed by this cation. In carnallite the K+ cations occupy an identical space to the ammonium ion in novograblenovite, but when embedded into the latter crystal structure it is bound less tightly. Voids occupy 14% of the space in the novograblenovite crystal structure. Novograblenovite is exactly the same phase as the ‘redikortsevite’ described previously from Chelabinsk coal dumps and this informally introduced name should be abandoned.

Matulaite was first described by Moore and Ito (1980) from the Bachman mine, Hellertown, Northampton County, Pennsylvania, USA. Its ideal formula was reported as CaAl18(PO4)12(OH)20·28H2O, based on wet-chemical analysis. Re-examination of both existing cotype specimens of matulaite revealed no material matching the powder or single-crystal X-ray diffraction data reported for the species. Other samples examined from the type locality, as well as from the LCA pegmatite in North Carolina, USA, and Fumade, Tarn, France, provided material crystallographically consistent with matulaite: P21/n, a = 10.604(2), b = 16.608(4), c = 20.647(5) Å , b = 98.848(7)° and Z = 4. Electron microprobe and crystal structure analysis of newly studied material from the type locality showed the ideal formula of matulaite to be Fe3+ Al7(PO4)4(PO3OH)2(OH)8(H2O)8˙8H2O. The chemical composition reported by Moore and Ito (1980) was most probably determined on a mixture of mostly kobokoboite and afmite, with lesser amounts of crandallite. As there is no matulaite on any of the existing cotype specimens of the species, the two specimens used to obtain the new chemical analyses, powder and single-crystal X-ray diffraction data and the structure determination are designated as neotypes. The neotypes have also been used to obtain crystal morphology and new measurements of the physical and optical properties of the species. The neotypes and new data have been approved by the CNMNC, proposal 11-F. The crystal structure of matulaite contains seven-member chain segments of AlO6 octahedra decorated by PO4 tetrahedra. The PO4 tetrahedra also link to isolated FeO6 octahedra, resulting in a 'pinwheel' Fe(PO4)6 group. The linkage of octahedra and tetrahedra defines a thick layer parallel to {001}. The only linkage between layers is via hydrogen bonding to interlayer water molecules.

Three members of the pyroxene group, blanfordite, manganoan diopside, and brown manganiferous pyroxene, form important constituents of the manganese silicate rocks (gondite) of the metamorphosed manganese formations of India. The chemical composition of blanfordite is variable within the diopside-acmite series, that of the manganoan diopside corresponds to the diopside end of this series, and the brown manganiferous pyroxenes are related to aegirine-augites. The majority of the blanfordites studied have a composition within the aegirine-augite field, so that compositionally most of the blanfordites and brown manganiferous pyroxenes are similar in spite of the difference in their pleochroic schemes; The chemical composition of blanfordite varies: in association with calc-magnesian metasediments it has a high percentage of diopside, whereas in gondites and pegmatites its composition approaches more towards the acmite end. The blanfordites are often associated with manganiferous amphiboles such as juddite (manganoan magnesioriebeckite) and winchite (richterite-tremolite with blue and pink pleochroism) but never with tirodite. The brown manganiferous pyroxenes, on the other hand, are associated intimately with tirodite (richterite-tremolite with pleochroism in shades of yellow) but never with winchite and juddite.

Natural samples of the substituted basic Cu(II) chloride series, Cu4–xMx2+(OH)6Cl2(M = Zn, Ni, or Mg) were investigated by single-crystal X-ray diffraction in order to elucidate compositional boundaries associated with paratacamite and its congeners. The compositional ranges examined are Cu3.65Zn0.35(OH)6Cl2 – Cu3.36Zn0.64(OH)6Cl2 and Cu3.61Ni0.39(OH)6Cl2 – Cu3.13Ni0.87(OH)6Cl2, along with a single Mg-bearing phase. The majority of samples studied have trigonal symmetry (R3̄m) analogous to that of herbertsmithite (Zn) and gillardite (Ni), with a ≈ 6.8, c ≈ 14.0 Å. Crystallographic variations for these samples caused by composition are compared with both published and new data for the R3̄m sub-cell of paratacamite, paratacamite-(Mg) and paratacamite-(Ni). The observed trends suggest that the composition of end-members associated with the paratacamite congeners depend upon the nature of the substituting cation.

Optical and microprobe investigations have been made on the metal and silicate portions of four particles > 1 mm extracted from the magnetic fraction of lunar soil bulk sanaple 14162,80. Three of the particles have structures and compositions similar to those encountered in the < 1-mm fraction of this bulk sample. One of the particles shows a complex arrangement of melted metal, unmelted metal, micronorite, and vitroclastic silicate material. The structure of this particle is reported in detail and its structure is explained in terms of preferential melting of metal-phosphide interfaces under the influence of shock events operating on material at a temperature of about 650°C.

It is shown here that dyke rocks of type localities for ‘soda-minettes’ are not minettes (= lamprophyres dominated by phlogopite and K-rich feldspar). It has long been suggested that ‘soda-minette’ also be applied to otherwise normal minettes from elsewhere that carry modally variable amounts of groundmass aegirine and/or, more commonly, arfvedsonitic to riebeckitic amphibole. Despite the presence of sodic pyriboles, these rocks are poorer in Na2O then minettes lacking these phases. ‘Soda-minette’ is thus misleading and self-contradictory to the many petrologists to whom ‘soda-’ legitimately connotes that the rock in question either has K/Na < 1 and/or is rich in albitic feldspar. To eliminate this ambiguity it is recommended, with the approval of twenty-six other petrologists, that ‘soda-minette’ no longer be used as a rock name. As minettes with Na-pyribole(s) are markedly K-rich and most are both ultrapotassic and peralkaline, independent of the modal abundance of the Na-pyrobile, it is suggested that one of these three chemical characteristics be utilized adjectivally in naming these minettes.