A phonolite dyke at Mount Goonneringerringgi, south-eastern Queensland, carries prominent pink specks of eudialyte, together with manganoan pectolite (ranging to calcian serandite), aegirine, albite, arfvedsonite, nepheline, natrolite, and analcime. This is the first confirmed occurrence of eudialyte in Australia

We document the occurrence of Fe-bearing trioctahedral micas in the Poudrette quarry in the Mont Saint-Hilaire alkaline intrusion, characterize them by microprobe analysis, Mössbauer spectroscopy, X-ray diffraction, and optical measurements, describe their mineral chemistry, and discuss their petrological significance. In the nepheline and sodalite syenite, biotite and annite occur as coarse crystals characterized by low Al content (typically 2 atoms per formula unit, a.f.u.), high Mn content (typically 0.2 to 0.8 a.f.u.) and variable Fe/(Fe+Mg) values from 0.61 to 0.97. In the gabbro, biotite is less Fe-rich, has lower Mn content and high Ti content. Phlogopite is found as small metamorphic crystals in marble xenoliths within the syenite and siderophyllite occurs as large crystals in a metasomatized albitite dyke. Fe3+/Fetot values extend from 0.079 in the siderophyllite to 0.282 in a high-Fe3+ annite. All of the micas except for the phlogopite have high contents of (Fe3+)iv (∼0.13 to 0.45 a.f.u.) despite the high availability of Al in the rocks. We suggest that the high (Fe3+)iv amounts are caused by the high Mn abundance via a local structural mechanism. The great variety of mica encountered at Mont Saint-Hilaire reflects the highly heterogeneous conditions that prevailed during magmatic and postmagmatic crystallization in this intrusion.

Qandilite, a new species of the spinel group, has been found in a forsterite-rich rock in contact with a kaersutite-rich banded diorite from the Qala-Dizeh region, NE Iraq. Chemical analysis yielded MgO 29.62, FeO 10.32, MnO 0.76, Fe2O3 28.27, Al2O3 4.83, TiO2 26.41, SiO2 0.02, sum 100.23 wt. %. This analysis calculates to [(Mg1.20Ti0.60)][Mg0.12Mn0.02)(Al0.17)]O4 with a composition of Mg2TiO4 63.8, MgFe2O4 12.8, FeFe2O4 23.4 mole %. Qandilite is cubic with a = 8.4033±0014 Å; cell volume 593.40 Å3 and space group Fd3m; Z = 8. The seven strongest lines in the X-ray diffraction pattern are (d,I,hkl): 2.971, 30, (220); 2.53, 100, (311); 2.101, 45, (400); 1.617, 50, (333, 511); 1.486, 60, (440); 1.0938, 30, (553, 731); 0.9704, 25, (555, 751). The colour is black, lustre metallic, streak black, fracture even and the cleavage perfect on (111). It is opaque, strongly magnetic, Dcalc = 4.04, Dmeas = 4.03, and VHN100 = 960–1045 kg/mm2, with H-7. The reflection colour is grey with a pinkish tint; it is isotopic with no internal reflections. Reflectance measurement data in air and oil in the range (400–700 nm) are given. Colour values for illuminant C in air and oil in terms of CIE colour space are: x = 0.307, 0.307; y = 0.311, 0.310; Y% = 13.10, 3.0; λd = 465, 460; and Pe% = 2.0, 2.2. Calculated data for the absorption coefficients (k) and refractive indices (n) in the range 400–700 nm are also presented.

Hydrothermal conversion of single crystals of calcite, CaCO3, dolomite, CaMg(CO3)2, and magnesite, MgCO3, was carried out in ammonium phosphate buffer solution. While calcite easily forms a pseudomorph of hydroxylapatite, Ca5(PO4)3OH, it takes several weeks to convert magnesite into pseudomorphic dittmarite, (NH4)Mg(PO4)·H2O. The conversion of dolomite, as the compositional intermediate, also proceeded slowly, but yielded a biphasic pseudomorph composed of whitlockite, Ca9Mg(PO4)6O(PO3OH), and dittmarite. To our knowledge, this is the first description of a biphasic pseudomorph with chemically and structurally different phases. Near the surface, the two phases formed a porous layered structure, while towards the core of the single crystal a fine-grained mixture of both minerals precipitated. The initially sequential pattern of precipitation of Ca-rich whitlockite followed by Mg-rich dittmarite can be explained by dissolved Mg ions being adsorbed onto the dolomite surface or incorporated into hydrated magnesium complexes, retarding crystallization of dittmarite. Surface adsorbed Mg ions impeding further dissolution of dolomite also partly accounts for the observed lower reaction rates of dolomite and magnesite, as compared to calcite. An additional factor decreasing the reaction rates of dolomite and magnesite is a considerable increase in molar volume upon conversion, which restricts the formation of porosity and, hence, ion transport to the reaction front.

Cell dimensions have been measured from correctly indexed powder patterns of thirty natural and two synthetic orthopyroxenes. The natural specimens (mostly metamorphic) contain exsolved phases largely avoided during microprobe chemical analysis. Linear regression analysis between the cell dimensions and Mg, Al, Ca contents (ignoring minor elements) was quite unsatisfactory until a term in Mg2 was added. Two separate regression analyses for the ranges Mg 0–0·5 and 0·5–1 using only Mg, Al, and Ca were satisfactory. Olivine yielded satisfactory regressions for the whole range without a term in Mg2 (Louisnathan and Smith, 1968). The difference between olivine and pyroxene results from absence of site preference by Mg and Fe in olivine compared to strong preference in pyroxene revealed by electron density and Mössbauer studies (Bancroft, Burns, and Howie, 1967; Ghose and Hafner, 1967).

The data were recalculated by means of a new best-fit procedure developed by Hey in which the errors in the chemical and physical parameters are considered simultaneously.

Earlier measurements of a and b for plutonic pyroxenes are consistent within possible experimental uncertainties with those given here; however a and b data obtained by Kuno and by Hess on volcanic specimens are considerably higher by variable amounts. Although there are uncertainties in the Ca content and its effect on a and b, the larger dimensions probably result from lower site preference as indicated by Mössbauer studies.

Prediction of Mg, Ca, and Al from just the cell dimensions is only moderately accurate even for metamorphic orthopyroxenes.

Mn-rich graftonite, (Ca,Mn2+)(Fe2+,Mn2+)2(PO4)2, ferrisicklerite, Li1–x(Fe3+,Mn2+)PO4, manganoan apatite, (Ca,Mn2+,Fe2+Mg)(PO4)3Cl, staně kite, Fe3+Mn2+O(PO4) and Mn-rich vivianite, (Fe2+)3(PO4)2·8H2O, occurring in a granitic pegmatite at Soè Valley (central Alps, Italy) were characterized by powder and single-crystal X-ray diffraction (XRD) and electron microprobe analyses. Geochemically, the Mn-rich graftonite phases are poorly evolved Fe/Mn-phosphates of rare-earth elements-lithium (REE-Li) granitic pegmatites. The assemblage Mn-rich graftonite + ferrisicklerite + staněkite has rarely beendocumen ted in pegmatites. Inthe Soè Valley pegmatite, ferrisicklerite forms exsolution lamellae with Mn-rich graftonite associated with manganoan apatite and staněkite. Graftonite is associated with Mn-rich vivianite. Powder and single-crystal XRD data indicate that the unit-cell volume of graftonite increases as a function of Mn2+ content. Staněkite shows a distinctly smaller unit-cell volume with respect to previously reported staněkites, probably due to reduced Mn2+. Vivianite with significant Mn2+ has a unit-cell volume similar to nearly Mn-free vivianite. The formation of Mn-rich graftonite and manganoan apatite is related to destabilization of Mn-rich almandine and biotite during pegmatite formation. Ferrisicklerite forms exsolution lamellae along the 010 cleavage planes of Mn-rich graftonite, whereas staněkite forms by alterationof ferrisicklerite and Mn-rich vivianite due to circulation of late-stage hydrothermal fluids.

New occurrences of xenolithic alkaline rocks from three East African volcanoes are described. Micro-ijolites and alkali pyroxenites occur in the carbonate-rich tufts and lavas of Mount Elgon; kaersutite-rich pyroxenites and a suite of fenitized basement rocks in the caldera flows of Mount Meru, and apparently unique melanocratic hortonolite nepheline syenites in the central foyaite plug of Mount Kenya. The 87Sr/86Sr ratios indicate mantle origin, and all are enriched in trace elements such as Sr, Nb, and Zr. The xenoliths from Mount Kenya are cumulate equivalents of the glassy kenyte lavas of the mountain; the pyroxenites of Mount Elgon are also cumulates whose predominant titanaugite is of identical composition to that of the host lavas. The contrast between the 'dry' Elgon pyroxenites and the 'wet' amphibole-rich types from Mount Meru is believed to reflect different CO2/H2O ratios in the volatile phase accompanying the alkaline vulcanicity. Strongly alkaline, carbonate-rich suites such as that of Mount Elgon derive from fairly dry alkali-basaltic magma under high CO2 activity by dominant pyroxene fractionation, whereas the mildly alkaline lineage seen in some areas of Mount Meru forms under more hydrous conditions in which amphibole fractionation is important. Mount Meru in addition shows a transition to rock-types typical of the strongly alkaline lineage, and this is reflected in the occurrence of relatively amphibole-poor pyroxenites with the amphibole-rich types.

The fine lamellar structure (pl. IV, fig. 1 a and b) which is described here is very common in the orthopyroxenes of plutonic and regionally metamorphosed rocks. This structure can be seen under crossed nicols in sections inclined at a high angle to the optic axial plane (100), except on those sections which make a low angle with (001). When the main part of the crystal is in extinction, the fine lamellae stand out because their extinction position is different from that of the main crystal. Although this structure is common, it is not described in any of the widely used text-books, but several descriptions and references to it have been published in recent years. The purpose of this paper is to draw attention to the nature of this lamellar structure.

A series of albites was synthesized in the presence of aqueous NaOH fluids (concentration 0 to 4N NaOH, Pfluid = 15000 1b/in2) over the temperature range 300 to 500 °C. At fixed temperature-pressure conditions increasing NaOH concentration of the initial fluid can be correlated with decreasing obliquity of the albites.

The new mineral ammoniomathesiusite (NH4)5(UO2)4(SO4)4(VO5)·4H2O, was found in the Burro mine, San Miguel County, Utah, USA, where it occurs as a secondary phase on asphaltum/quartz matrix in association with ammoniozippeite, gypsum, jarosite and natrozippeite. The mineral forms pale yellow to greenish-yellow prisms, up to ~0.3 mm long, with pale-yellow streak and bright yellow–green fluorescence. Crystals are transparent and have vitreous lustre. The mineral is brittle, with Mohs hardness of 2½, stepped fracture and two cleavages: excellent on {110} and good on {001}. The calculated density is 3.672 g/cm3. Ammoniomathesiusite is optically uniaxial (–) with ω = 1.653(2) and ε = 1.609(2) (white light). Pleochroism is: O = green-yellow, E = colourless; O > E. Electron microprobe analyses yielded the empirical formula [(NH4)4.75(UO2)4(SO4)4(VO5)·4(H2.07O). The five strongest powder X-ray diffraction lines are [dobs Å(I)(hkl)]: 10.57(46)(110), 7.10(62)(001), 6.41(100)(101), 3.340(35)(240) and 3.226(44)(141). Ammoniomathesiusite is tetragonal, P4/n with a = 14.9405(9), c = 7.1020(5) Å, V = 1585.3(2) Å3 and Z = 2. The structure of ammoniomathesiusite (R1 = 0.0218 for 3427 I > 2σI) contains heteropolyhedral sheets based on [(UO2)4(SO4)4(VO5)]5– clusters. The structure is identical to that of mathesiusite, with ${\rm NH}_{\rm 4}^{\rm +} $ in place of K+.

Graphitic, quartz-rich black slate within the Late Ordovician Abercrombie Beds, Lachlan Fold Belt, southeast Australia, has undergone contact metamorphism adjacent to the Siluro-Devonian Wyangala Batholith. This produced porphyroblasts of andalusite and cordierite, and smaller grains of pale green phengitic mica. Later regional metamorphism caused complete retrogression of cordierite and partial retrogression of andalusite, with margarite replacing some andalusite.

The aluminous minerals andalusite, margarite and phengite all contain V and Cr substituting for Al. Andalusite has up to 1.39% V2O3 and 1.09% Cr2O3, margarite has up to 1.07% V2O3 and 0.37% Cr2O3, and phengitic mica has up to 6.93% V2O3 and 1.52% Cr2O3. This mica also has BaO contents of up to 1.96%.

Chemical analyses reveal very high SiO2 contents for these rocks (about 89%), carbon contents of about 2%, and extremely low CaO, FeO, MgO and Na2O. Although V and Cr are prominent in aluminous minerals, their concentrations in the rock are only about average for black shales. However, Ba values range from 2000 to 6000 p.p.m., well above average for black shales. It is suggested that V and Cr probably precipitated from sea water, but Ba may have been concentrated by planktonic organisms such as radiolaria.

Garnet pyroxenite xenoliths from the Delegate nephelinitic breccia pipes, New South Wales, Australia, contain relict garnets (py40 alm39 gr21) which are replaced by dark kelyphitic rims resulting from garnet breakdown. The kelyphite is composed of a lamellar intergrowth of secondary minerals, in which the lamellae are <1 μm in width. Analyses by SEM and ICPMS reveal that the kelyphite has an identical bulk chemical composition to the primary garnet. Kelyphitic rims on garnet are well known from xenoliths and xenocrysts in kimberlite pipes and from tectonically-uplifted mafic and ultramafic rocks in some metamorphic terranes. Orthopyroxene occurs in metamorphic kelyphites and it has been assumed that orthopyroxene is also the breakdown product of garnet transported in basic-ultrabasic magmas. However, TEM study of Delegate kelyphite shows that the ultrafine lamellae do not contain orthopyroxene but are instead composed of magnesian clinoferrosilite (En45Fs55), and lesser ferroan spinel and anorthite. The clinoferrosilite is probably the inversion product of initially-formed magnesian protoferrosilite. The breakdown reaction is believed to result from a sudden change to lower temperature and pressure conditions when the xenoliths were transported in the Delegate magma from ∼40 km depth to the surface.

The alteration mineralogy of two outcrops of basaltic lavas in northeast Ireland is studied with respect to the hydrothermal alteration history of basalts. Evidence for contact between basaltic flows and palaeorivers or palaeolakes is reported in both outcrops, which belong to two different formations: the Lower Basaltic Formation (LBF) and the Inter Basaltic Formation (Causeway Tholeiite Member, CTM). The secondary minerals consist of layer silicates (chlorite-smectite, C-S, di- and trioctahedral smectites), zeolites, calcite and silica minerals and there is a repetition of the sequence of alteration mineralogy in each formation. The mineralogy of phyllosilicates from the LBF (C-S) corresponds to hotter conditions of alteration than those of CTM (di/trioctahedral smectites), while the zeolite mineralogy is controlled by the fluid composition. In consequence, the mineralogy and the distribution of alteration minerals suggest that the crystallization of phyllosilicates and zeolites did not develop during burial of lavas a long time after the eruption, but reflects thermal gradients driven by lava heat flow and marked by local perturbation caused by regional water flow through the aquifer zone in the lava during the last cooling of each lava sequence.

The petrology of a massive olivine-sulphide interplanetary dust particle shows melting of Fe,Ni-sulphide plus complete loss of sulphur and subsequent quenching to a mixture of iron-oxides and Fe,Ni-metal. Oxidation of the fayalite component in olivine produced maghemite discs and cellular intergrowths with olivine and rare andradite-rich garnet. Cellular reactions require no long-range solid-state diffusion and are kinetically favourable during pyrometamorphic oxidation. Local melting of the cellular intergrowths resulted in three dimensional symplectic textures. Dynamic pyrometamorphism of this asteroidal particle occurred at ∼1100°C during atmospheric entry flash (5–15 s) heating.

Wedge-shaped layers of ultramafic and mafic cumulates in Intrusion II of the Caledonian Honningsvåg Intrusive Suite suggest crystallization on an inclined magma chamber floor from a compositionally-zoned and density-stratified magma.

Cyclic unit 8 (140–100 m thick) consists of a distally-thinning olivine gabbro (denoted paoC) macrolayer overlain by a distally-thickening gabbronorite, pahC. New mineral data in four traverses across cyclic unit 8 show systematic compositional changes; the Mg# of the mafic phases decreases upwards through the unit and distally, both along the base and along the paoC/pahC interface.

A crystallization model based on an effectively continuously-zoned magma chamber with numerous, relatively thin, double-diffusive magma layers is proposed. Differential migration of horizontal isopleths (e.g. Mg# and aSiO2) in response to fractional crystallization and assimilation of country rock can explain the variations in the Mg# of the cumulates.

Type specimens of the molybdoarsenates betpakdalite, natrobetpakdalite and obradovicite and the molybdophosphates mendozavilite, paramendozavilite and melkovite, and similar material from other sources, have been examined in an effort to elucidate the relations among these phases, which we designate as the heteropolymolybdate family of minerals. Using electron microprobe analysis, X-ray powder diffraction and single-crystal X-ray diffraction with crystal structure determination where possible, it was found that natrobetpakdalite, mendozavilite and melkovite are isostructural with betpakdalite and that obradovicite has a closely related structure.

The betpakdalite and obradovicite structure types are based on frameworks containing four-member clusters of edge-sharing MoO6 octahedra that link by sharing corners with other clusters, with Fe3+O6 octahedra and with PO4 or AsO4 tetrahedra (T). The structures differ in the linkages through the Fe3+O6 octahedra, which produce different but closely related framework configurations. The structures contain two types of non-framework cation sites, which are designated A and B. In general, there are two or more A sites partially occupied by disordered, generally larger cations that are coordinated to O atoms in the framework and to H2O molecules. The B site is occupied by a smaller cation that is octahedrally coordinated to H2O molecules. The general formula for minerals with either the betpakdalite or the obradovicite structure is: [A2(H2O)nB(H2O)6][Mo8T2Fe3+3O30+7(OH)7–x], where x is the total charge of the cations in the A and B sites (+3 to +7) and n is variable, ideally 17 for arsenates and 15 for phosphates. The ideal total number of A cations is defined as 2 in the general formula, but varies from 1 to 3.8 in analysed samples. Dominant cations at the A site include K, Na and Ca and at the B site Na, Ca, Mg, Cu and Fe. The combinations that have been identified in this study define six new heteropolymolybdate species.

A suffix-based nomenclature scheme is established for minerals of the betpakdalite, mendozavilite and obradovicite groups, with the following root names based on the structure types and the T-site cations: betpakdalite (T = As), mendozavilite (T = P) and obradovicite (T = As). Two suffixes of the form -AB, corresponding to the dominant cations in the two different types of non-framework cation sites complete the species name. The historical name melkovite is retained rather than introducing mendozavilite-CaCa.

Our investigation of the paramendozavilite type specimen revealed no paramendozavilite, but an apparently closely related new mineral; however, another sample of paramendozavilite analysed had K > Na.

A new occurrence of varlamoffite is described, and the results of chemical analysis, differential thermal analysis, and infra-red spectrographic analysis are presented. It is suggested that varlamoffite is of secondary origin resulting from the attack of meteoric waters on stannite.

A new calcium aluminum silico-phosphate mineral has been found at two locations on Newry Hill, Newry, Maine, U.S.A. Its composition closely approximates to 3CaO.3·5Al2O3.3SiO2.2P2O5.18H2O (Z = 1). Perhamite is uniaxial (+), c = 1577, ω = 1·564, density = 2·64 g/cm3. The mineral is hexagonal, probably P6/mmm, with a = 7·02 Å, c = 20·21 Å. The colour is light brown to white, the habit is as aggregates of discoidal hexagonal crystals. Cleavage is perfect {0001}, the lustre is vitreous, and the streak white. The mineral is named for a pegmatite miner and geologist, Frank C. Perham of West Paris, Maine, U.S.A.

The most similar species is viséite. A re-examination of viséite indicates that the composition previously given is incorrect. A new form of viséite, also from Visé, Liège, Belgium is also examined and found to differ in composition from the type material.

Chemical analyses for ganomalite from Franklin, New Jersey, and Jakobsberg, Nordmark, Sweden, imply that Mn is an essential element and that the formula is Pb9Ca5MnSi9O33, with Z = 1 for the hexagonal unit cell. Preliminary crystal structure data confirm that Mn and Ca are ordered, as implied by the chemical analyses. Ganomalite is hexagonal, space group P3, with a = 9.82 and c = 10.13 Å. Occurrences of samples from both localities are described, together with analytical data for macedonite from Jakobsberg.

Aspidolite, the Na analogue of phlogopite, ideally NaMg3AlSi3O10(OH)2, occurring in hornfels from a contact aureole in Kasuga-mura, central Japan, has been approved as a mica species by the Commission on New Minerals and Mineral Names of the International Mineralogical Association. Aspidolite is interleaved with and surrounded by phlogopite. Based on its mode of occurrence, phlogopite is classified into two types; (1) phlogopite interleaved with aspidolite (= interleaved phlogopite) and (2) phlogopite rim. The aspidolite-phlogopite assemblage is associated with amphibole (pargasite-magnesiosadanagaite), titanite, calcite, scapolite, apatite, pyrrhotite and chalcopyrite. A representative chemical formula of aspidolite is (Na0.90K0.10)∑1.00(Mg2.27Al0.41Fe0.232+Ti0.05)∑2.96 (Al1.44Si2.56)∑4.00O10(OH1.97F0.03)∑2.00. Aspidolite has almost fully occupied the interlayer site; its Na/(Na+K) ratio ranges from 0.67 to 0.95. It has more tetrahedral Al (1.38—1.48 a.p.f.u. for O = 11) than the ideal aspidolite end-member showing progression of tschermakite-type substitution. The alternation of aspidolite and phlogopite parallel to the (001) plane may indicate a miscibility gap between these two phases. The phlogopite rim is interpreted as a later product, probably formed metasomatically. Aspidolite is optically biaxial negative with elongation positive and Z ‖ cleavage. Two polytypes (1M and 1A) of aspidolite were identified in X-ray powder diffraction patterns. Aspidolite-1M is monoclinic, space group C2/m, with refined unit-cell parameters a = 5.291(8), b = 9.16(2), c = 10.12(2) Å, β = 105.1(1)°, V = 473(1) Å3, Z = 2. Aspidolite-1A is triclinic, space group C, with a = 5.289(6), b = 9.16(1), c = 9.892(9) Å, α = 94.45(9), β = 97.74(9), γ = 90.0(1)°, V = 473.4(9) Å3, Z = 2.