In specimens of Mn skarn from the type locality of Långban, hyalotekite, (Ba,Pb,K)4Ca2−(Si,B,Be)12O28F, occurs in a matrix consisting mostly of aegirine (⩽22 mol.% CaMnSi2O6), andradite (⩽27 mol.% Mn3Fe2Si3O12), hematite, pectolite, quartz, calcite, baryte, barylite, and hedyphane. Melanotekite, plumbian taramellite, ferrian K-feldspar (to 6.5 wt.% Fe2O3), rhodonite, a talc-like mineral, apophyllite, and several Pb-As-Sb-O minerals are found in trace amounts. In a single specimen of reedmergnerite-microcline pegmatite from Dara-i-Pioz, hyalotekite occurs in close association with microcline. Other accessory minerals are albite, aegirine, pyrochlore, eudialyte, and polylithionite. The optical constants for hyalotekite from Långban and Dara-i-Pioz are, respectively, α = 1.656, 1.646, β = 1.659–1.660, 1.649, γ = 1.670–1.671, 1.659 (all ± 0.002), 2Vγ (mcas) = 57.2–60.5 ± 0.5°, 57.0 ± 1.1°(λ = 589 nm). Cell parameters of the Dara-i-Pioz hyalotekite for a body-centred triclinic cell are: a = 11.284(2), b = 10.930(1), c = 10.272(8) Å, α = 90.35(2)°, β = 90.11(3)°, γ = 89.98(1)°. Electron and ion microprobe data show that Långban hyalotekite is heterogeneous even within a given sample; the most important substitutions are Pb = Ba, K and coupled B = Si and B = Be. Minor constituents include Mn in the Långban hyalotekite and Na in the Dara-i-Pioz hyalotekite, which also differs in its significantly higher Ba/Pb ratio. Conditions suggested for hyalotekite formation at Långban and Dara-i-Pioz are P ⩽ 4 kbar, T ⩾ 500°C, silica saturation, peralkalinity, and relatively high oxygen fugacities and low sulphur fugacities. These temperatures must have been sufficiently high to allow for miscibility of Pb with Ba (and K) despite the lone pair of electrons of Pb2+.

Two distinct generations of pyrite, with different morphologies, are described from the Proterozoic Broken Hill-type Pinnacles deposit in western NSW. The earlier, py1, forms concentric layers interpreted as colloform banding. Although the textures are somewhat similar to those observed in supergene alteration zones, textural relationships in fresh rocks suggest that these are pre-metamorphic and that the pyrite formed as the result of precipitation from hydrothermal fluids in open veins, vugs and fissures. The second generation, py2, post-dates py1 and forms euhedral overgrowths on it. It is interpreted as being synchronous with the main phase of base metal sulphide mineralisation. The textures reported here are previously unrecorded for Broken Hill-type mineralisation, and have implications for the regional identification of feeder zones to the Broken Hill deposit. The evidence supports a model in which mineralising conditions at the Pinnacles were characterised by slightly higher oxygen and lower sulphur fugacity (further constrained by Fe contents of sphalerite) than at Broken Hill, where pyrrhotite is the major Fe sulphide.

The pre-metamorphic textures observed in the pyrite at the Pinnacles deposit are also unusual because they have survived granulite facies metamorphism and five phases of deformation, whereas previously the preservation of such textures has not been recognised at metamorphic grades greater than amphibolite facies.

The rare zeolite mineral gobbinsite has been found in vugs of altered basalts at the Magheramorne Quarry, Lane, Northern Ireland, intimately associated with phillipsite. The crystal chemistry of the sample (Na4.3Ca0.6Si10.4Al5.6O32·12H2O) is close to that reported for gobbinsite from the type locality. The crystal structure of the Magheramorne gobbinsite has been refined from X-ray powder diffraction data using the multiphase Rietveld full profile technique. The orthorhombic Pmn21 space group is confirmed. The refined cell parameters (a = 10.1027(5), b = 9.8016(5), and c = 10.1682(6) Å) are slightly different from those reported in the literature for the K-rich gobbinsite from Island Magee (a = 10.108(1), b = 9.766(1), and c = 10.171(1) Å), whose structure was also refined from powder data.

Combustion experiments up to 1400°C were carried out with subbituminous coals from the Teruel power station, the Teruel Mining District, the Santa Eulalia coal deposit and with lignite from the As Pontes power station in Spain. The characterisations of the occurrence and distribution of inorganic matter and its transformation during combustion of these coals were carried out by means of X-ray diffraction and optical and electron microscopy. The combustion experiments show that the incorgainc transformations during the combustion of all the coals studied vary depending on the sulphur and calcium contents. The sulphur, iron and calcium contents govern the quality of anhydrite crystallisation (which takes place between 600 and 900°C Furthermore, the high calcium oxide content produces the fouling of the combustion wastes at relatively low temperatures (1200°C), prevents the occurrence of mullite and magnetite in the ashes and leads to the crystallistation of anorthite and esseneite during the colling. The comparison of the inorganic phases of fly ashes and slags from the Teruel power station with those of the experimental wastes shows that the inorganic transformations during coal combustion in the power station can be predicted by means of laboratory furnace experiments provided that the residence time in the flame and the effect of the cooling and evacuation controls of gases and particles from the power station are taken in consideration.

Arsenic-rich nagyagite (up to 5.5 wt % As) has been discovered in samples from the Au-Ag-Te deposit of Sacarimb, western Romania. Optical properties of the mineral show small but distinct differences to nagyagite (ss). Chemical analyses indicate a substitution of As for Sb, and chemical zonation suggests rapid changes in the chemistry of the mineralising fluids.

Apatite in most igneous intrusions has a high Cl/F ratio. However, chlor-apatite has been reported in the lower portions of the Bushveld and Stillwater Complexes. This has been used as evidence supporting the early separation of a Cl-rich discrete hydrous fluid in these intrusions. Mineralogical evidence is presented here to demonstrate that the Bushveld Complex, at least, formed from a nearly anhydrous magma, and did not release a hydrous fluid before apatite began to crystallize. It is suggested that apatite in the earliest cumulates equilibrated with trapped interstitial liquid, which converted it from the typical F-rich composition of cumulus apatite to a Cl-rich composition. This is an analogous process to that in which cumulus mafic minerals may become more Fe-rich on cooling and reaction with interstitial liquid.

The concept of force of crystallization is combined with that of depression of dissolution to explain diagenetic volume-for-volume replacement in both cases, either when the pressure is increased in early sedimentary settings, or when it is diminished in a late exposure. Also, a new textural criterion is added to the three classical ones in order to recognize diagenetic volume-for-volume replacement, and calculations are carried out to estimate the speed of the replacement.

Two subsilicic magnesian potassium-hastingsites (4.55 and 4.34 wt.% K2O) and one magnesian potassium-hastingsite occur in calc-silicate pods in well-layered gneisses from the transitional amphibolite- and granulite-facies terrain of a Cambrian metamorphic complex, East Antarctica. Subsilicic magnesian potassium-hastingsite is the most K-rich Ca-amphibole yet reported:

The crystal chemistry of clinopyroxene, orthopyroxene and olivine from a crushed fragment of the H5 Zaoyang chondrite has been investigated by X-ray structure refinement and detailed microprobe analysis. The meteoritic pyroxenes have cell and polyhedral volumes which compare well with such data from terrestrial pyroxenes that typically crystallize at low-pressure. Fe2+ and Mg are rather disordered in M1 and M2 sites of clino- and orthopyroxenes; the closure temperatures of the exchange reaction are 600 and 512°C respectively, which is consistent with a reasonably fast cooling rate, estimated to be of the order of 1°C/day.

The closure temperature for the intercrystalline Ca-Mg exchange reaction for clino- and orthopyroxenes is 900°C as calculated from clino- and orthopyroxene intergrowth.

The cooling rates obtained from Fe2+-Mg intracrystalline partitioning suggest a cooling of the order of degrees per day at temperatures of 600–500°C due to a strong loss of heat by irradiation.

A study of apatite crystals from the Asio mine, Japan, showed sectoral texture related to the growth of the crystal, and with optically biaxial properties within the sectors. Wet chemical analysis gave a composition Ca5(PO4)3(F0.64,OH0.38,Cl0.01)1.03 for the specimen.

Additional diffraction spots were not observed in precession and oscillation X-ray photographs and electron diffraction photographs. Since the internal textures correlate with the surface growth features, it is suggested that the internal textures and the unusual optical properties were produced during nonequilibrium crystal growth. The fluorine/hydroxyl sites in hexagonal apatite are symmetrically equivalent in the solid crystal but, at a growth surface, this equivalence may be lost, resulting in a reduction of crystal symmetry. Heating of the apatite to about 850°C results in the almost complete disappearance of the optical anomalies due to disordering, which may be related to the loss of hydroxyl from the crystal.

The structure of the mineral schultenite, PbHAsO4, has been studied using pulsed neutron single crystal diffraction. The low-temperature, low-symmetry structure is found to exhibit substantial ordering of the hydrogen atom onto one of two possible sites, which are equally occupied in the high-temperature phase above 313 K. The occupancies found at low temperature agree well with the normal behaviour for such a hydrogen ordering phase transition in this type of material. In addition the heavy atom lattice distortion has been characterised as a function of temperature and found to follow broadly the pattern of hydrogen ordering. Higher-temperature measurements at and above the phase transition confirm the high symmetry nature of the structure in this region, with no significant distortions from this within the resolution of the present data.

Wycheproofite is a new hydrated sodium aluminium zirconium phosphate from a pegmatite vein in granite at Wycheproof, in northwestern Victoria, Australia. The mineral occurs as compact, finely fibrous masses in small cavities in the quartz/feldspar/muscovite/schorl-bearing pegmatite. The fibrous crystals are between 5 and 10 µm wide and up to several mm long. Accompanying minerals include two other zirconium phosphates — kosnarite and a new species, selwynite, the K-analogue of gainesite — as well as wardite, eosphorite, cyrilovite, leucophosphitc, rockbridgeite, a kidwellite-like mineral and saleeite. The wycheproofite aggregates are pale pinkish to brownish orange, with a vitreous to pearly lustre. The streak is colourless, fracture rough, cleavage not observed and the Mohs hardness is between 4 and 5. Optical data are incomplete due to the fibrous nature of the mineral; the indices of refraction are in the range 1.62–1.64. The measured density is 2.83 g cm−3. Chemical analysis gave (wt.%) Na2O 6.36, K2O 0.44, CaO 0.66, FeO 0.36, MnO 0.21, Al2O3 12.03, Cs2O 0.03, ZrO2 32.43, HfO2 1.24, P2O5 35.85, SiO2 0.23, F 0.34, H2O 9.0, less 0=F 0.14, Total 99.04. The simplified formula is NaAlZr(PO4)2(OH)2·H2O. Wycheproofite is triclinic with unit cell parameters a=10.926(5) Å, b = 10.986(5) Å, c = 12.479(9) Å, α= 71.37(4)°, β = 77.39(4)°, γ= 87.54(3)° V = 1375.9 Å3. For Z= 6, the calculated density is 2.81 g cm-3. The strongest lines in the X-ray powder diffraction pattern are [dobs (Å), Iobs,hkl] 2.603 (100) 040; 4.128 (80) 121; 3.711 (65) 023; 3.465 (60) 030; 8.865 (40) 101; 3.243 (35) 132. The crystal structure has not been solved due to the finely fibrous nature of the material available. The name is for the locality, which in the local Australian Aboriginal language means ‘witchie bushes growing on a hilltop’.

Data on the third occurrence of kosnarite, KZr2(PO4)3, at Wycheproof are also given.

In the arid, Late Precambrian terrain of southern Israel, a complex suite of minerals and amorphous species were deposited in host gneiss from fluids under near-neutral conditions within 1 m of the surface. The morphology of secondary gold appears to relate to its host mineral (skeletal-dendritic with quartz; multi-faceted crystals with arsenates; spherical droplets with iron oxide). The gold is very fine-grained, and was most likely complexed as a thiosulphate.

Three amorphous phases are present (iron oxide, chrysocolla, Cu-Mn-(Fe-As) silicate). At least in part, gold and baryte appear to have crystallized out of a metal-Fe-oxide gel. Other minerals, including apatite, anglesite, and conichalcite, may have grown from appropriate crystallites present in the gel.

The conichalcite occurs mainly as bladed to acicular radial spherulites. In the presence of lead, a solid solution phase between duftite and conichalcite (‘Pb-conichalcite’) was formed.

The evolution of Fe-containing phases of carbonaceous chondrites heated under various oxidation-reduction conditions was investigated by means of Mössbauer spectroscopy. Heating of the lower petrological types of chondrites (CM2) released gases which initially produced oxidizing conditions (∼450°C) and then reducing conditions (> 700°C Phase transformation occurred rapidly (during 1–5 minutes) at all temperatures. During heating the Fe-bearing phyllosilicate phases in CM2-chondrite converted to Fe-bearing olivine, metallic iron and troilite (pentlandite). These phases resemble those of CO3, CV3 and EH-chondrites. Iron distribution resembling that of ordinary chondrites (some additional Fe2+ in pyroxene) was obtained only by heating a mixture of oxidized matter (CM2) with reduced matter (EH).

A phase transition discovered at 1050°C is probably the temperature boundary between conditions of formation of the two main components of ordinary chondrites: matrix and chondrules. Chondrules of ordinary chondrites may be formed at temperatures > 1050°C while the matrix forms at temperatures < 1050°C For the carbonaceous chondrite Kainzas (CO3) these temperatures are approximately 1000°C and < 900°C The experimental conditions determined for the evolution of chondrites do not contradict the theoretical two-component model of Wood-Anders-Ringwood and may further its development.

A suite of orthopyroxenes from spinel Iherzolite xenoliths associated with basanites occurring in the Victorian (Australia) post-Pliocene ‘Newer Volcanics’ province was investigated by means of a crystal chemical methodology which provides accurate site occupancy and site configuration parameters.

The M1 configuration is essentially constrained by AlVI rather than Fe2+. In addition, Fe3+, Cr3+ and Ti4+ are confined to M1 (Molin, 1989) and AlIV to TB. M2 is controlled by FeM22+ ⇌ MgM2, constrained by (Fe2+ + Ca)M2 > 0.14 atoms per formula unit (p.f.u.). Cation substitution in TB and M2 constrains the sum of the volumes of the respective polyhedra VTB+VM2 to remain essentially constant. Therefore, M2 favours the retention of the large Fe2+ up to melting-point, causing non-ideality of this iron-depleted orthopyroxene. As a consequence, the investigated orthopyroxene can be considered an ultimate Fe2+ carrier during partial mantle melting.

Schwertmannite is a new oxyhydroxysulphate of iron from the Pyhäisalmi sulphide mine, Province of Oulu, Finland. It occurs there, and elsewhere, as an ochreous precipitate from acid, sulphate-rich waters. Associated minerals at other localities may include jarosite, natrojarosite, goethite and ferrihydrite. Schwertmannite is a poorly crystalline, yellowish brown mineral with a fibrous morphology under the electron microscope. A high specific surface area in the range of 100 to 200 m2/g, rapid dissolution in cold, 5 M HCl or in ammonium oxalate at pH 3, and pronounced X-ray diffraction line broadening are consistent with its poorly crystalline character.

Colour parameters for the type specimen as related to CIE illuminant C are L* = 53.85, a* = + 15.93, and b* = +47.96. Chemical analysis gives Fe2O3, 62.6; SO3, 12.7; CO2, 1.5; H2O−, 10.2; H2O+, 12.9; total 99.9 wt.%. These data yield an empirical unit cell formula of Fe16O16(OH)9.6(SO4)3.2·10H2O after exclusion of CO2 and H2O−. The most general simplified formula is Fe16O16(OH)y(SO4)z·nH2O, where 16 − y = 2z and 2.0 ⩽ z ⩽ 3.5. Schwertmannite has a structure akin to that of akaganéite (nominally β-FeOOH) with a doubled c dimension. Its X-ray powder diffraction pattern consists of eight broad peaks [dobs in (Iobs) (hkl)] 4.86(37)(200,111); 3.39(46)(310); 2.55(100)(212); 2.28(23)(302); 1.95(12)(412); 1.66(21)(522); 1.51(24)(004); and 1.46(18)(204,542), giving a = 10.66(4), c = 6.04(1) Å, and V = 686(6) Å3 for a primitive, tetragonal unit cell. The probable space group is P4/m. Upon heating, schwertmannite transforms to hematite with Fe2(SO4)3 occurring as an intermediate phase. Bidentate bridging complexes between Fe and SO4 are apparent in infrared spectra. Mössbauer data show the Fe in schwertmannite to be exclusively trivalent and in octahedral coordination; it has a Néel temperature of 75 ± 5 K and a saturation magnetic hyperfine field of about 45.6 T. Pronounced asymmetry of the Mössbauer spectra indicates different locations for Fe atoms relative to SO4 groups in the structure. The name is for Udo Schwertmann, professor of soil science at the Technical University of Munich.