A specimen of zirconolite, collected from the type locality of the mineral originally described as zirkelite at Jacupiranga, São Paulo, Brazil has been re-examined and its mineral chemistry more completely characterized. All crystals studied are metamict and display very fine lamellar oscillatory zoning (1–3 µm in width) superimposed on a sector zonation. Such zoning, observed in backscattered electron images, is primarily related to differences in the concentration of Th.

In comparison with other reported zirconolite samples from a variety of geological occurrences, Jacupiranga zirconolite has higher Ca, Th, (Nb + Ta) and lower Ti and REE, which is consistent with its occurrence in carbonatitic rocks. The compositional variation with respect to an ideal zirconolite is described by two main coupled substitutions:

Calzirtite, Ca2Zr5Ti2O16, although intergrown with zirconolite and with identical major components, shows much less compositional variability with only minor amounts of Nb and Ta substituting for Ti. Unlike zirconolite, the REE and actinide elements are not easily accommodated in the calzirtite structure.

Fresh and weathered pyrochlore from the Lueshe carbonatite complex (in the northeast of the Democratic Republic of Congo) was studied by Fourier transfom infrared (FTIR) spectroscopy and by a combination of FTIR spectroscopy and thermal analysis. The former was carried out in the spectral range 400–4000 cm−1. The spectra for fresh and weathered pyrochlores were very different. For the weathered pyrochlore, two bands were identified as OH vibration modes, one broad band with a maximum at 3413 cm−1 and another finer band at 1630 cm−1. The fresh pyrochlore does not show OH absorption bands. The presence of OH confirms the hydrated state of the weathered pyrochlore suggested by previous microanalytical work. The combination of FTIR spectroscopy and thermal analysis allows ‘real-time’ observation of gas emanations and solid-state transformations taking place during heating up to 800°C. For fresh pyrochlore, no solid transformation was detected, except a CO2 emanation from 242–576°C. For the weathered pyrochlore a dehydration was observed between 234–565°C followed by an exothermic peak in Differential Scanning Calorimetric (DSC) curve at 604°C. This exothermic peak corresponds to the formation of a Nb oxide phase. At higher temperatures the weathered pyrochlore is partly decomposed, forming a dehydrated pyrochlore and a Nb oxide phase. The combination of FTIR and thermal analysis has provided useful information on both fresh and weathered pyrochlore transformations which has clarified our understanding of the water control of the structural stability of pyrochlore minerals.

A kinetic and X-ray study of the dehydroxylation of datolite, CaBSiO4(OH), has shown that the decomposition occurs very rapidly above 700°C in air, with an activation energy for the reaction of the order of 200 kcal mole −1. The transformation is topotactic, the dehydroxylated phase being tetragonal with a 7·14 Å, c 4·82 Å, and particularly well formed even at the lowest temperatures of decomposition. Single-crystal studies have shown that two orientations of the new phase exist and that the original a of datolite becomes the unique axis of the tetragonal phase while the tetragonal a axes are oriented either parallel to or at 45° to the b and c axes of datolite. The new phase appears to be a boron-containing analogue of the melilite structure, composition Ca2SiB2O7, but is metastable. The basic sheet structure is preserved during the transformation but a reorganization of the tetrahedral layer from the 4- and 8-membered rings of datolite to the 5-membered rings of the new phase is involved, together with effective removal of protons and some silicon. The transformation can be explained in terms of an inhomogeneous reaction mechanism involving migration of calcium and boron into the new phase domains and counter-migration of silicon and protons, but with only minor readjustment of oxygens. The high activation energy of the reaction is explicable in terms either of the effort necessary to remove silicon from the domains of the new phase or of the difficulty of moving the large calcium ions through a relatively close-packed structure.

The new mineral gazeevite, BaCa6(SiO4)2(SO4)2O (R3m, a = 7.1540(1), c = 25.1242(5) Å, V = 1113.58(3) Å3, Z = 3), was found in an altered xenolith in rhyodacites ofthe Shadil-Khokh volcano, Southern Ossetia and at three localities in larnite pyrometamorphic rocks of the Hatrurim Complex; Nahal Darga and Jabel Harmun, Judean Mountains, Palestinian Autonomy, and Har Parsa, Negev Desert, Israel. Larnite, fluorellestadite–fluorapatite, srebrodolskite–brownmilleriteand mayenite-supergroup minerals are the main minerals commonly associated with gazeevite. Gazeevite is isostructural with zadovite and aradite; the 1:1 type AB6(TO4)2(TO4)2W, occurs together with the structurallyrelated minerals of the nabimusaite series, 3:1 type AB12(TO4)4(TO4)2W3, where A = Ba, K, Sr...; B = Ca, Na...; T = Si, P, V5+, S6+, Al...; W = O2–,F–. Single antiperovskite layers {[WB6](TO4)2} in the structure type of gazeevite–zadovite and triple {[W3B12](TO4)4} layers in arctite–nabimusaite areintercalated with single A(TO4) layers. These minerals with an interrupted antiperovskite structure are characterized by a modular layered structure derived from hatrurite, Ca3(SiO4)O. Gazeevite is colourless, transparent, with a white streakand vitreous lustre. Gazeevite is brittle, shows pronounced parting and imperfect cleavage on {001}; it is uniaxial (–), ω = 1.640(3), ε = 1.636(2) (λ = 589 nm) and nonpleochroic; Mohs' hardness is ∼4.5, VHN50 = 417 kg mm–2. The calculateddensity is = 3.39 g cm–3. The main lines of the calculated powder X-ray diffraction pattern are as follows (d(Å)/I/hkl): 3.58/100/110, 3.07/91/021, 2.76/47/116, 1.789/73/220, 3.29/60/113, 2.78/36/024, 2.12/25/125, 2.21/21/208. Raman spectra of gazeeviteare compared with spectra of other minerals. The formation of gazeevite and minerals of the nabimusaite–dargaite series is connected with high-temperature alteration of an early assemblage of clinker minerals affected by later fluids generated by volcanic activity or combustion processes.

The new mineral popovite, Cu5O2(AsO4)2, was found in the sublimates of the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with ericlaxmanite, kozyrevskite, urusovite, lammerite, lammerite-β, johillerite, bradaczekite, tenorite, hematite, aphthitalite, anhydrite, langbeinite, calciolangbeinite, As-bearing orthoclase, etc. Popovite occurs as prismatic or tabular crystals and as grains up to 0.2 mm in size forming clusters up to 1.5 mm in size and as crusts on basalt scoria or on aphthitalite incrustations. Popovite is transparent with a vitreous to greasy lustre. Its colour is olive green to dark olive-green, but fine-grained varieties are light yellow-green. The mineral is brittle, with Mohs' hardness ∼3½. Cleavage was not observed and the fracture is uneven. Dcalc is 5.30 g cm–3. Popovite is optically biaxial (+), α = 1.84(1), β ≈ 1.86, γ = 1.96(1), 2Vmeas = 50(20)°. The Raman spectrum is given. Chemical data (wt.%, electron-microprobe) are CuO 63.28, ZnO 0.56, V2O50.12, As2O5 35.80, SO3 0.27, total 100.03. The empirical formula, based on 10 O a.p.f.u., is (Cu4.99Zn0.04)Σ5.03(As1.95S0.02V0.01)Σ1.98O10. Popovite is triclinic, P1̄, a = 5.1450(3), b = 6.2557(3), c = 6.2766(4) Å, α = 100.064(5), β = 96.351(5), γ = 95.100(5)°, V = 196.47(1) Å3 and Z = 1. The strongest reflections in the powder X-ray diffraction pattern [d, Å (I)(hkl)] are 3.715(36)(110, 101), 3.465(43)(11̄1), 2.968(90)(01̄2), 2.927(100)(111), 2.782(31)(1̄02), 2.768(67)(1̄20), 2.513(55)(1̄2̄1) and 2.462(67)(2̄01). Popovite has a novel structure type. Its crystal structure, solved from single-crystal X-ray diffraction data (R = 0.0459), is based on (010) layers forming an interrupted framework. The layer consists of Cu(1)O6 octahedra with very strong Jahn-Teller distortion and Cu(2)O5 and Cu(3)O5 polyhedra. The linkage between the layers is reinforced by isolated AsO4 tetrahedra. Popovite is named in honour of the Russian mineralogists Vladimir Anatol'evich Popov (b. 1941) and Valentina Ivanovna Popova (b. 1941), a husband and wife research team working in the Institute of Mineralogy of the Urals Branch of the Russian Academy of Sciences, Miass, Russia.

Room temperature Mössbauer and electron-probe measurements of Fe3+/ΣFe in chromite from the mantle section of the Oman ophiolite define two groups of samples: a low Fe3+/ΣFe group (with Fe3+/ΣFe = 0.21–0.36) have cr# = Cr/(Cr + Al) in the range 0.49–0.75, whereas a smaller more geographically localized high Fe3+/ΣFe group (with Fe3+/ΣFe = 0.71–0.78) have a more restricted range of cr# ratios of 0.72–0.75. The low Fe3+/ΣFe chromitites have very variable Fe3+/ΣFe ratios. They are thought to have crystallized from melts that have interacted with depleted mantle and thereby acquired their variable Fe3+/ΣFe ratio. The high Fe3+/ΣFe chromitites are restricted to one small area of the mantle and their high oxidation state is thought to be post magmatic. They are either the product of later heating, related to melt flux or interaction with a later oxidising melt. A difference in oxygen fugacity between the MORB-depleted harzburgite host, which is at the quartz–fayalite–magnetite (QFM) buffer and the later chromite-bearing melts (QFM + 2) implies that there is a real difference in the oxidation state of the MORB and arc-magma sources.

Hoganite, copper(II) acetate monohydrate, and paceite (pronounced ‘pace-ite’), calcium(II) copper(II) tetraacetate hexahydrate, occur as isolated crystals embedded in ferruginous gossan from the Potosi Pit, Broken Hill, New South Wales, Australia. They are associated with goethite, hematite, quartz, linarite, malachite, azurite, cerussite and cuprian smithsonite. Hoganite is bluish green with a pale blue streak and a Mohs hardness of 1½; it possesses perfect {001} and distinct {110} cleavages and has a conchoidal fracture. Chemical analysis of hoganite gave (wt.%) C 23.85; H 3.95; Cu 31.6; Fe 0.4; O (by difference) 40.2, yielding an empirical formula of C4H7.89O5.07Cu1.00Fe0.01. The simplified formula is C4H8O5Cu or Cu(CH3COO)2.H2O, the mineral being identical to the synthetic compound of the same formula. Single-crystal X-ray data for hoganite are: monoclinic, space group C2/c, a = 13.162(3), b = 8.555(2), c = 13.850(3)Å, β = 117.08(3)°, Z = 8. The density, calculated from single-crystal data, is 1.910 g cm−3. The strongest lines in the X-ray powder pattern are [dobs (Iobs) (hkl)] 6.921 (100) (011); 3.532 (28) (202); 6.176 (14) (200); 3.592 (11) (22); 5.382 (10) (11); 2.278 (10) (204); 5.872 (9) (002). Hoganite (orientation presently unknown) is biaxial positive with α = 1.533(2), β = 1.541(3), γ = 1.554(2), 2V(meas.) = 85(5)°, 2V(calc.) = 76.8°, dispersion is r < v, medium (white light); it is strongly pleochroic with X = blue, Y = pale bluish, Z = pale bluish green and absorption X > Y > Z. The mineral is named after Graham P. Hogan of Broken Hill, New South Wales, Australia, a miner and well-known collector of Broken Hill minerals.

Paceite is dark blue with a pale blue streak and a Mohs hardness of 1½; it possesses perfect {100} and {110} cleavages and has an uneven fracture. Chemical analysis of paceite gave (wt.%) C 21.25; H 5.3; Ca 9.0; Cu 14.1; O (by difference) 50.35, yielding an empirical formula of C8H23.77O14.23Ca1.02-Cu1.00. The simplified formula is C8H24O14CaCu or CaCu(CH3COO)4.6H2O, the mineral being identical to the synthetic compound of the same formula. Unit-cell data (refined from X-ray powder diffraction data) for paceite are: tetragonal, space group I4/m, a = 11.155(4), c = 16.236(17)Å, Z = 4. The density, calculated from refined cell data, is 1.472 g cm−3. The strongest lines in the X-ray powder pattern are [dobs (Iobs) (hkl)] 7.896 (100) (110); 3.530 (20) (310); 5.586 (15) (200); 8.132 (8) (002); 9.297 (6) (101); 2.497 (4) (420); 3.042 (3) (321). Paceite is uniaxial positive with ω = 1.439(2) and ɛ = 1.482(3) (white light); pleochroism is bluish with a greenish tint (O), pale bluish with a greyish tint (E), and absorption O ⩾ E. The mineral is named after Frank L. Pace of Broken Hill, New South Wales, Australia, an ex-miner and well-known collector of Broken Hill minerals.

High-pressure amorphization of anorthite has been observed by energy-dispersive X-ray diffraction of powdered samples held under static pressure in a diamond anvil cell. The onset of amorphization is accompanied by a significant reduction in the intensity of Bragg reflections at pressures between 10 and 14 GPa, and anorthite becomes completely X-ray amorphous between 14 and 20 GPa. These pressures are significantly lower than those suggested by earlier birefringence studies. The discrepancy can be reconciled in terms of a model of high-pressure amorphization in which partially amorphized anorthite can be regarded as a spatially heterogeneous anti-glass, with long-range order maintained but translational disorder dominating at shorter correlation lengths.

The equilibrium solubility of mimetite has been determined in aqueous solution at 298.2K. For the reaction Pb5(ASO4)3Cl(s,mimetite)+6H+(aq)⇌5Pb2+(aq)+3H2AsO4−(aq)+Cl−(aq) at this temperature log KH+, extrapolated to zero ionic strength, is equal to −27.9(4). This value is equal, within experimental error, to that corresponding to pyromorphite, Pb5(PO4)3Cl, derived from the literature, and redetermined here under analogous conditions. Distribution coefficients in terms of both HXO42− and H2XO4−(aq) ions (X = P,As) have also been determined for solid phases of the pyromorphite-mimetite solid solution series containing from 5 to 95 mol. % mimetite. Although the two end-members are isostructural without being strictly isomorphous, the solid solution series behaves ideally over the whole compositional range; that is, the composition of the solid phase reflects the ratio of arsenate to phosphate species in aqueous solution at pH values corresponding to naturally-occurring aqueous solutions generally associated with the oxidized zones of base metal orebodies. Some relationships between mimetite and other secondary lead(II) and copper(II) arsenate minerals have been explored.

Electron microprobe analyses are presented of chevkinite-group minerals occurring as microphenocrysts in peralkaline rhyolites of the Greater Olkaria Volcanic Complex (Kenya) and as a groundmass phase in a peralkaline quartz trachyte lava from the Tarosero volcano (Tanzania), both in the East African Rift Valley. Their compositions conform closely to the formula: (REE, Ca, Th)4 Fe2+ (Fe2+, Al, Ti, Zr, Nb)2 Ti2 (Si4O22). Compared to published analyses of chevkinite-group minerals, the Olkaria phases are relatively enriched in Nb and the LREE; the Tarosero phase is more calcic and relatively Zr- and Nb-rich. The main substitution in the A site at Olkaria is Ca ⇌ Ce. The overall charge-balancing substitution seems to be (McDowell, 1979):

Phenocryst/glass ratios are presented for Nb, REE, Sr, Th, U and Y in two, and Ba, Zr and Hf in one, Kenyan samples. Partition coefficients are lower in the more peralkaline rock, with the exception of Sr, which is higher. The lower values are consistent with a lower degree of polymerization of more peralkaline melts. The higher Sr value may be a function of Sr partitioning into phenocryst phases coexisting with chevkinite.

Minerals approximating to the formulae PtSb2, PtSb, Pt(Sb,Bi), (Pt,Ir)As2, Pt(Ir,Os)2As4, Pd2CuSb, Pd(Sb,Bi), Pd8CuSb3, Pt4Sn3Cu4, and (Fe,Ni)2S have been discovered as fine intergrowths in platinum concentrates from the Driekop mine, Transvaal, South Africa. Conventional ore microscopy also proved the presence of most of the known minerals of the platinum paragenesis. The name geversite is proposed for the phase PtSb2.

A study of augite in over three hundred thin sections of mainly alkalic rocks permits the distinction of two main types of hour-glass structure. The common ‘swallow-tailed’, sometimes skeletal augite crystals are found in the fine-grained groundmass of many rock types, and it is suggested that rapid crystallization alone accounts for their formation. Hence, this type of hour-glass structure has been called ‘quench hour-glass’. The hour-glass structures of larger augite crystals of porphyritic and coarse-grained rocks are commonly described as hour-glass ‘zoning’, as they result primarily from compositional differences between the different sectors. These were formed under conditions of relatively slower cooling than the ‘quench hour-glass’, and thus cannot be explained in the same way. They are thought to have formed by a process involving adsorption of impurities on a particular crystal face so as to impede growth of these faces, producing an initial skeleton of hour-glass form, which is completed by later crystallization of augite richer in FeO, Na2O, TiO2, and Al2O3. This hypothesis also explains the patchy zoning of other augite crystals, casting doubt on some petrogenetic interpretations of such zones as core zones.

One of the problems which occupy the mineralogist as well as the geologist or pedologist is the mechanism of the formation and evolution of minerals in nature. In this general connexion we have been trying to clarify the possibility of passing from montmorillonite to chloritic minerals. Already in a previous work we showed that on precipitating magnesium with ammonia in the presence of montmorillonite, a substance is obtained which shows certain of the characteristics of vermiculite and chlorite. Having thus shown the possibility of passing from one type to the other, we wished to clarify the mechanism of the change. We wanted to know what are the conditions of the transformation, and then to follow the montmorillonite from the moment when it was in equilibrium with the solution of magnesium chloride to the end of the alteration. Finally, it had to be established to what extent the product obtained resembled or differed from the standard minerals. These different points will be considered in succession.

Ceylon moonstone is probably the best known variety of those alkali-felspars which display a prominent internal colour reflection or ‘schiller’. On account of its blue sheen and its clear transparency, the mineral has attained a certain degree of popularity and some value as a gem-stone.

In the investigation of a suite of leucite-lamproites from the West Kimberley area of Western Australia, carried out in the Department of Mineralogy and Petrology, Cambridge, during the period 1937–38, a number of unusual minerals were noted. Three of these were isolated and analysed and two of them proved to be new species. The present paper deals mainly with the three minerals analysed. They are—

1. (l) Magnophorite, a new amphibole allied to katophorite.

2. (2) Wadeite, a new potassium-zirconinm silicate.

3. (3) Titaniferous phlogopite.

The leueite-bearing rocks occur at a number of isolated volcanic vents, nineteen of which have been examined and mapped by Dr. A. Wade. They have in every instance broken through sedimentary déposits of Permian age. Considerable diversity is to be seen in the rock types developed, but they are all characterized by high potash, magnesia, and titania, with low alumina and soda. Analyses of some types which indicate the general chemical character of these rocks are given in table I.

A vitric fiamme containing BaO-bearing sanidine (BaO = 11 wt.%) was sampled (via di Fioranello, Rome) in the pyroclastic products of the Lower Flow Unit (LFU) belonging to the Villa Senni Eruption Unit in the Colli Albani Volcanic District (Roman Comagmatic Province, Central Italy). The fiamme of the LFU is essentially made up of glass, in which scarce phenocrysts of BaO-bearing sanidine, leucite and Al2O3-bearing Ca-clinopyroxene occur. In this paper the various parameters controlling barium partitioning between alkali feldspar and LFU liquid, are discussed.

Combined structural and textural studies of the quartz veins of the Panasqueira W-Cu-Sn deposit of central Portugal have revealed the presence of coeval forms of crack-seal and cavity-fill mineral textures. The textures result from the dilational and infilling histories of brittle fractures produced within the host rock by the intrusion of pressurised fluids. Crack-seal textures were produced wherever or whenever crystal growth rates matched or were greater than fracture dilation rates, whereas cavity-fill textures developed wherever or whenever dilation rates were quicker than those of crystal growth. Rates of dilation within the blade-like fissures were naturally lowest at the edges, where types of crack-seal textures were produced, and highest in the cores, where cavity-fill texture formed. During propagation the linkage of adjacent echelon blades, by the rupture of the host-rock straps (bridges) between them, enhanced dilation rates and led to the widespread development of cavity-fill textures. Within the composite fissures so produced, environments in which types of crack-seal textures could form were restricted to the fissure margins and to areas where the tensile strain was sympathetically shared between closely spaced fissures. Textures and minerals characteristic of each fracture environment were able to form simultaneously within the fracture system.

In this reconnaissance study, skeletal materials from people, dating from ∼1500 B.P., who lived by or worked at the ancient copper mines and furnaces of the Wadi Faynan in southern Jordan, were analysed using atomic absorption spectrophotometry (AAS) to determine the intensities of accumulation of copper and lead in their bones. Many of the bones analysed contained concentrations of these metals which are comparable to those of modern individuals who are heavily exposed to metals through contemporary industrial processes.

Patterns of partitioning throughout the skeleton of a number of individuals were also studied. These AAS data suggest that within the human organism there may be some ability to influence the patterns of accumulation of copper within the skeleton. The humerus was frequently found to contain more copper than other bones studied. Within the humerus itself, the medial epicondyle frequently contained the highest concentrations, which may indicate a significant degree of organization or control of the process. These metal concentration data together with their toxicological consequences suggest that the health of the ancient human populations must have been adversely affected by exposure during life to copper in the environment. They also point to the need for further detailed studies of metal partitioning within the bones of the human skeleton.

The new minerals fermiite (IMA2014-068), Na4(UO2)(SO4)3·3H2O and oppenheimerite (IMA2014-073), Na2(UO2)(SO4)2·3H2O, were found in the Blue Lizard mine, San Juan County, Utah, USA, where they occur together as secondary alteration phases in association with blödite, bluelizardite, chalcanthite, epsomite, gypsum, hexahydrite, kröhnkite, manganoblödite, sideronatrite, tamarugite and wetherillite.

Fermiite descriptive details: pale greenish-yellow prisms; transparent; vitreous lustre; bright greenishwhite fluorescence; white streak; hardness (Mohs) 2½; brittle; conchoidal fracture; no cleavage; slightly deliquescent; easily soluble in RT H2O; densitymeas = 3.23(2) g cm–3; densitycalc = 3.313 g cm–3. Optically, biaxial (+), α = 1.527(1), β = 1.534(1), γ = 1.567(1) (white light); 2Vmeas. = 51(1)°, 2Vcalc. = 50°; dispersion r < v, distinct. Pleochroism: X, Y = colourless, Z = pale greenish yellow; X = Y < Z. Energy dispersive spectroscopic (EDS) analyses yielded the empirical formula Na3.88(U1.05O2)(S0.99O4)3(H2O)3. Fermiite is orthorhombic, Pmn21, a = 11.8407(12), b = 7.8695(5), c = 15.3255(19) Å, V = 1428.0(2) Å3 and Z = 4. The structure (R1 = 2.21% for 1951 Io > 3σI) contains [(UO2)(SO4)3] chains that are linked by bonds involving five different Na–O polyhedra to form a framework. The mineral is named for Italian-American theoretical and experimental physicist Dr. Enrico Fermi (1901–1954).

Oppenheimerite descriptive details: pale greenish-yellow prisms; transparent; vitreous lustre; bright greenish-white fluorescence; white streak; hardness (Mohs) 2½; slightly sectile; three good cleavages, {110}, {011} and {101}; irregular fracture; slightly deliquescent; easily soluble in RT H2O; densitycalc = 3.360 g cm–3. Optically, biaxial (+), α = 1.537(1), β = 1.555(1), γ = 1.594(1) (white light); 2Vmeas. = 72(2)°, 2Vcalc. = 70°; dispersion is r > v, moderate, inclined; optical orientation: X ≈ ⊥ {101}, Z ≈ [111]; pleochroism: X very pale greenish yellow, Y pale greenish yellow, Z greenish yellow; X < Y < Z. EDS analyses yielded the empirical formula Na1.94(U0.97O2)(S1.02O4)2(H2O)3. Oppenheimerite is triclinic, P1, a = 7.9576(6), b = 8.1952(6), c = 9.8051(7) Å, α = 65.967(5), β = 70.281(5), γ = 84.516(6)°, V = 549.10(8) Å3 and Z = 2. The structure (R1 = 3.07% for 2337 Io > 3σI) contains [(UO2)(SO4)2(H2O)] chains that are linked by bonds involving two different Na–O polyhedra to form a framework. The mineral is named for American theoretical physicist Dr. J. Robert Oppenheimer (1904–1967).