bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zinc- and Y-group-bearing senaite from St Peters Dome, and new data on senaite from Dattas, Minas Gerais, Brazil
Authors: Foord Eugene E. , Sharp William N. , Adams John W. 
Published: December 2006

AbstractA Zn- and Y-group-bearing senaite, formulated as AM21O38 (Pb0.63Na0.46Ba0.11)Σ1.20(Ti14.64Zn1.74Y‒group REE0.70Mn0.38Nb0.20Sn0.03Zr0.03Th0.02)Σ20.9O38, a member of the crichtonite group, is a newly characterized phase associated with murataite at the St Peters Dome area, Colorado. The Zn- and Y-group-bearing senaite is uranium-free and nonmetamict, but otherwise is comparable to known senaites and davidites in X-ray diffraction pattern, symmetry, and structure. The REE distribution shows a strong dominance of Y and the Y-group REE which are present in M(1). Megascopically, the mineral is black, submetallic, and opaque; in polished section it appears to be white and moderately bright compared with murataite. Cleavage is absent but twinning on {520} is present.Senaite and hitherto unreported zinc-bearing senaite from Dattas, Diamantina, Minas Gerais, Brazil, have the following respective structural formulas as determined by electron microprobe:(Pb0.76Sr0.20La0.08Ce0.07Ba0.04)Σ1.15(Ti12.89Mn0.88Y0.59Zn0.12Mg0.07Nb0.03Cr0.02Th0.02)Σ20.61O38and(Pb0.89Ba0.15Ce0.02Sr0.02)Σ1.08(Ti14.57Zn1.76Na0.63Mn0.50Y0.28Nb0.14Mg0.04Cr0.02)Σ20.83O38
Fluorine in sarcolite: additional history and new chemical data
Authors: Livingstone A. 
Published: December 2006

AbstractThe historical background leading to the discovery of sarcolite by Thomson is reviewed. Many mineralogical reference works quote Thompson (1807) but no paper on sarcolite by Thomson has been found; also the spelling of Thomson is incorrect on numerous occasions. The history of sarcolite from its original discovery is reviewed. Chemically, sarcolite is inadequately characterized in spite of a structural study by Giuseppetti et al. (1977). All known chemical analyses are collated and discussed. Two new analyses, using a combination of gravimetric, colorimetric, atomic absorption, and electron probe methods, are presented which show sarcolite to contain 2 wt. % flourine. The presence of this element in sarcolite was reported in 1860 but no quantitative data given; the new determinations cast some doubt over certain aspects of the sarcolite structure.Measured densities of sarcolite range from 2.93 to 2.96 (mean 2.95) gm/cm3; the tetragonal unit cell of a 12.32 and c 15.48 Å leads to a calculated density of 2.925 gm/cm3 using the empirical formula. Empirically sarcolite may be expressed as:Na1.38Ca6.0(Ca0.37,K0.13,Fe0.08,Sr0.07,Mg0.05)Σ0.70 Al3.90Si6.02P0.54O26.20F1.06C0.06and ideallyNa2Ca12(Ca,K,Fe,Sr,Mg)2Al8Si12(P,Si)O52F2and suggests 27 (oxygen and fluorine) atoms in the quarter unit cell.Details are given of the mineralogical assemblage, optical properties, infra-red and thermal behaviour of sarcolite which, after 176 years, is still known from only one locality—Monte Somma.
Compositional variations in glauconite
Authors: Buckley H. A. , Easton A. J. , Johnson L. R. 
Published: December 2006

AbstractVariation in composition, Fe3+/Fe2+ ratio, per cent mixed-layering, and d(060) spacing have been determined both between and within grains of glauconite from the Folkestone Beds at 286.5 m in the Tollgate bore, Sandwich, Kent. Grains extracted from the rock were classified on the basis of size into large (> 1 mm) and small (< 1 mm), and on colour into light and dark green. Large grains have a progressive increase in Fe3+/Fe2+ ratio with increase in total iron, while small grains have variable ratios; the largest variation is in the dark grains. The effect of the range of Fe3+/Fe2+ ratio variations on structural formula (e.g. R3+) is discussed. The per cent mixed-layering is not related to colour. There is a greater variation in Al, Fe, and K contents in and between large grains than small grains. Both sizes of grains may be separated on d(060) spacings determined by X-ray diffraction. Glauconite from coral and gastropod casts has different d(060) spacings than that from bryozoan casts and variegated grains, but is similar to the small grains. Large light grains may have developed from small light grains but it is unlikely that the large dark grains developed from small dark grains. The large grains probably all formed under similar conditions, with a common origin; the small from several sources or from a single source under a variety of conditions.
Macaulayite, a new mineral from North-East Scotland
Authors: Wilson M. J. , Russell J. D. , Tait J. M. , Clark D. R. , Fraser A. R. 
Published: December 2006

AbstractMacaulayite was found by the late I. Stephen (Soil Science Department, University of Aberdeen) in an outcrop of reddened, deeply weathered granite, near Inverurie, Aberdeenshire. It is blood red in colour, very fine-grained, and has refractive indices greater than 1.734. Its calculated density is 4.41 g/cm3. The mean of fourteen electron microprobe analyses in the anhydrous form is Fe2O384.67, Al2O34.01, SiO211.32%. With thermogravimetric data this leads to a formula of (Al3.38)Si7.95O86(OH)4; the ideal formula isSi4O43(OH)2. The cell indexes as C-centred monoclinic witha5.038,b8.726,c36.342Å, β 92°. The strongest X-ray lines are 36.6 (vs), 18.16 (vs), 3.700 (25), 2.720 (35), 2.533 (100), 2.214 (20), and 1.420 (35). Macaulayite has a layer structure, thought to consist of a double hematite unit terminated on both sides by silicate sheets and with water between these sheets. The infra-red spectrum includes absorption bands at 3597, 1052, 1033, and 858 cm−1, arising from the hydroxysilicate component of the mineral and at 647, 520, 438, 400, 304, and 227 cm−1corresponding to the platy hematite unit. The mineral is named for the Macaulay Institute for Soil Research and the name was approved by the Commission on New Minerals and Mineral Names of the International Mineralogical Association prior to publication.
A new occurrence of the hydrated aluminium sulphate zaherite, from Pofadder, South Africa
Authors: Beukes G. J. , Schoch A. E. , de Bruiyn H. , Van der Westhuizen W. A. , Bok L. D. C. 
Published: December 2006

AbstractA new occurrence of zaherite is reported from a sillimanite quarry 65 km west of Pofadder, Bushmanland, South Africa. It occurs as earthy white to light bluish-green cryptocrystalline material in narrow veins, in close association with natro-alunite and hotsonite, a new hydrated aluminium phosphate-sulphate. Scanning electron micrographs show an orientated wavy texture and tubular fibres. The optical and physical properties agree with those of the type material described from Pakistan, and it can be added that the mineral is biaxial positive with a moderate 2V and length-fast orientation. The new chemical analysis yields an ideal formula of Al12(SO4)5(OH)26·20H2O, which is identical to that of the type material. The white and light bluishgreen varieties are identical in major element composition but yielded trace Cu values of 1281 and 2408 ppm respectively. The X-ray powder diffraction pattern fits a triclinic symmetry (a 5.55, b 9.74, c 18.43Å, α 99.71°, β 89.13° γ 94.97°), and is dominated by one intense reflection at 18.12 Å, representing 001. The most important of the weak lines are (d, I, hkl): 9.56, 5, 010; 9.08, 4, 002; 4.82, 6, 01; 4.61, 8, 110; 4.56, 4, 02; 4.44, 4, 021; 3.61, 4, 1; 3.22, 8, 015. The differential thermal properties are characterized by endothermic peaks at 190, 470, and 685°C and a duplex at 880 and 910°C The infrared absorption spectrum is characterized by absorption bands centring about 905, 960, 985, 1150, 1700, and 3600 cm−1.
Mineral parageneses and metamorphic reactions in metasedimentary enclaves from the Archaean Gneiss Complex of north-west India
Authors: Sharma Ram. S. , Windley Brian F. 
Published: December 2006

AbstractThree metasedimentary enclaves up to a kilometre in length of contrasting compositions within the polymetamorphic Banded Gneissic Complex (> 2580Ma) have been studied for their mineral parageneses and metamorphic conditions. The largest enclave, consisting of kyanite-chloritoid-muscovite schist with quartz or corundum, and kyanite-fuchsite-corundum ± diaspore, was metamorphosed at most under lower amphibolite conditions, and is thus not isofacial with the surrounding schists and gneisses (of the ‘basement’ complex) which reached sillimanite-grade metamorphism in the last orogenic cycle (Aravalli: 1650–950Ma Orogeny) in Rajasthan.The second enclave is a calc-silicate rock which occurs as a small lens. The presence of two generations of wollastonite which formed during different metamorphic events in the calcite-quartz-grossularite-anorthite-clinopyroxene assemblage indicates polymetamorphism.The third enclave is a metabasic rock which records a complete polymetamorphic history in discontinuous zones in garnet coexisting with hornblende-chlorite-plagioclase-quartz±epidote. To explain the garnet zoning a model involving partial resorption of early garnet during the initial recrystallization stage of superimposed regional metamorphism is preferred to the alternative based on a single prograde metamorphism and retrogression.The mineralogy of the calc-silicate and metabasic enclaves gives a recrystallization temperature of c. 700°C and a pressure in the range of 8–3 kbar during the second metamorphism.
The International Mineralogical Association amphibole nomenclature scheme: computerization and its consequences
Authors: Rock N. M. S. , Leake B. E. 
Published: December 2006

AbstractA FORTRAN program has been written which inputs amphibole analyses, and outputs complete IMA-approved names, along with tabulated analyses, formula units, and IMA classification parameters. Several important corrections, additions, and amendments to the IMA scheme were found to be necessary. Two newly approved names have been incorporated—sadanagaite (ferro-pargasitic amphibole with Si < 5.5), and nyboite (alkali amphibole with (Na+K)A ⩾ 0.5, Fe3 ⩽ AlVI, Si < 7.5). The name anophorite (alkali amphibole with (Na+K)A ⩾ 0.5, Fe3 > AlVI, Si < 7.5) has been reinstated to complement nyboite, with the approval of the Amphibole Subcommittee of the IMA. Results of computer processing of several hundred analyses, which together cover the range of IMA-approved names, are summarized. These indicate substantial differences between IMA and previous nomenclature. The IMA-favoured procedure for reallocating total Fe in microprobe data is quite effective, except in kaersutites. Over half the analyses processed have anomalously high cations (e.g. Ca > 2), or cation totals (e.g. T + C + B > 15), commonly reflecting low H2O determinations. These prevent strict obeyance of the IMA site occupancy calculation rules. This problem can often be overcome by recalculation free of H2O, but other cases require modifications to the IMA rules. In particular, ‘misclassification’ of certain sodic-calcic amphiboles as edenite follows from transferring large excesses of C cations to the B site.
Calcium and magnesium hydroxide precipitation from alkaline groundwaters in Oman, and their significance to the process of serpentinization
Authors: Neal Colin , Stanger Gordon 
Published: December 2006

AbstractThe occurrence and genesis of Ca(OH)2 and Mg(OH)2 deposits associated with hyperalkaline groundwater from partly serpentinized ultramafic rocks in Northern Oman is reported. Two types of Ca(OH)2 deposit are differentiated; crystalline portlandite formed by the evaporation of Ca2+-2OH− spring waters, and a form of amorphous gel, not previously known in nature. The latter is a product of present-day low-temperature serpentinization. Mg(OH)2 (brucite) in both holocrystalline and gel forms is produced by mixing of Mg2+−2H surface waters with a Ca2+-2OH− groundwater in both surface and groundwater environments. These results indicate that significant differences exist between the processes of medium- and low-temperature brucite generation.
Occurrence of some Ni- and Sn-rich minerals in copper converter slags
Authors: Wearing E. 
Published: December 2006

AbstractThe chemistry of opaque spinel, delafossite (Cu2O·Fe2O3), cuprite (Cu2O), cassiterite, nickel-olivine (Ni2SiO4), and bunsenite (NiO) from some copper converter slags has been investigated by electron microprobe analysis. The spinel has a complex composition containing up to 33.89% NiO and 47.69% SnO2, ranging from essentially Ni2SnO4 to (Ni,Fe2+)O4. The associated delafossite contains up to 19.18% NiO and 38.15% SnO2. The chemical variation of the mineral phases is evaluated, and it appears that Ni2+ enters the spinel and delafossite to charge-balance the octahedrally coordinated Sn4+.
Nelenite, a manganese arsenosilicate of the friedelite group, polymorphous with schallerite, from Franklin, New Jersey
Authors: Dunn Pete J. , Peacor Donald R. 
Published: December 2006

AbstractNelenite, (Mn,Fe)16si12O30(OH)14[O6 (OH)3], is a polymorph of schallerite and a member of the friedelite group. X-ray diffraction patterns can be indexed on a supercell with a = 13.418(5) and c = 85.48(8)A, space group Rm, but by analogy with TEM results on mcGillite and friedelite, the structure is based on a one-layer monoclinic cell with a = 23.240, b = 13.418, c = 7.382 Å, β = 105.21°, and space group C2/m. Chemical analysis yields SiO2 31.12, FeO 17.12, MgO 0.12, ZnO 3.63, MnO 29.22, As2O3 12.46, H2O 6.42, sum = 100.09%. Analysis of a number of samples indicates that Fe substitutes for Mn up to 5.8 of the 16 octahedrally coordinated cations, but that the Si: As ratio is constant. The strongest lines in the X-ray powder diffraction pattern (d, I/Io) are: 2.552,100; 2.878,70; 1.677,60; 3.55,60; 1.723,50.Nelenite is brown in colour with a vitreous luster and perfect {0001} cleavage, which easily distinguishes it from schallerite. The Mohs' hardness is approximately 5. The density is 3.45 g/cm3 (calc.) and 3.46 g/cm3 (obs.). Nelenite is uniaxial negative with ɛ = 1.700 and ω = 1.718 (both ± 0.004). Nelenite was formerly known as ferroschallerite, which is a misnomer. It was found in the Franklin Mine, Franklin, Sussex County, New Jersey, in the 1920s. It occurs in several parageneses, associated with actinolite, tirodite, albite, garnet, feldspars, and several members of the stilpnomelane group in coarse-grained assemblages with pegmatitic texture and a breccia likely derived from this rock. Nelenite is named in honour of Joseph A. Nelen, chemist at the Smithsonian Institution.
Macphersonite, a new mineral from Leadhills, Scotland, and Saint-Prix, France— a polymorph of leadhillite and susannite
Authors: Livingstone A. , Sarp H. 
Published: December 2006

AbstractMacphersonite is white, resinous to adamantine, hardness (Mohs) 2½−3, density 6.50–6.55 gm/cm3 and possesses a perfect cleavage on {010}. Optically it is negative with 2Vα 35–36°, α = 1.87, β = 2.00 and γ = 2.01, α = b, γ = c, and γ = a, dispersion r > v. Polysynthetic twinning, with either coarse or fine lamellae, is common, as are contact twins. Crystals are orthorhombic, tabular on b with a 10.37, b 23.10 and c 9.25 Å, cell volume 2215.8 Å3 and space group Pcab; Z is 8 formula units. The seven strongest lines in the X-ray powder pattern are 3.274 (50) 052; 3.234 (100) 251; 2.654 (90) 351,203; 2.598 (30) 172, 400; 2.310 (30) 004, 371, 0.10.0; 2.182 (30) 263; and 2.033 (30) 234, 452, 154, 1.10.2. Electronprobe-microanalysis-determined chemistry leads to the empirical formula (Pb4.08, Cu0.10, Cd0.07)Σ4.25S0.90 C2.18O10.55(OH)1.58 which yields the ideal formula Pb4(SO4)(CO3)2(OH)2 and hence macphersonite is a polymorph of leadhillite and susannite. The infrared spectrum shows basic similarities to leadhillite and susannite spectra with additional diagnostic absorption bands. Macphersonite shows an identical thermogravimetric behaviour to that of leadhillite. It is associated, in varying combinations, with leadhillite, susannite, cerussite, caledonite, pyromorphite, scotlandite, galena, and the ‘lead hydroxyapatite’ of Temple (1955). The new mineral mimics leadhillite.
A new mineral, scotlandite (PbSO3) from Leadhills, Scotland; the first naturally occurring sulphite
Authors: Paar W. H. , Braithwaite R. S. W. , Chen T. T. , Keller P. 
Published: December 2006

AbstractElectron microprobe analysis of the new mineral scotlandite yielded Pb 72.27, S 9.95, corresponding to PbO 77.85, SO2 19.88, sum 97.73 wt.%. Secondary ion mass spectrometry showed the absence of Li, Be, B, C, N, and F, but the presence of very small amounts of Br. Infrared spectroscopy showed that the mineral is a sulphite with neither OH nor any other polyatomic anions. The empirical formula, calculated on the basis of Pb+S = 2 is Pb1.06S0.94O2.94 or ideally PbSO3.The mineral has the following vibrations of the sulphite ion in the infrared spectrum: v3 920, 865; v1 970 (?); v2 620, 600; v4 488, 470 cm−1.Scotlandite is monoclinic, with possible space groups P21 or P21/m. The unit cell dimensions are: a 4.542(2), b 5.333(2), c 6.413(2) Å, β 106.22(4)°, Z = 2. The strongest lines in the powder diffraction pattern are: 3.99(10) (011), 3.38(7) (110), 3.25(8) (11), 3.07(4) (002), 2.66(7) (020, 012), 2.56(4) (11), 2.24(5) (12, 102), 2.01(5)(210, 022), 1.707(4) (031), 1.538(4) (032, 004).Scotlandite occurs as chisel-shaped or bladed crystals elongated along the c-axis, with a tendency to form radiating clusters. The following forms have been determined: {100}, {010}, {011}, {021}, {031}, and {032}. The new mineral has a pronounced cleavage along {100}, and a less good one along {010}. The crystals are pale yellow to greyish-white and colourless, sometimes transparent. Their lustre is adamantine, pearly on cleavage planes.The mineral is optically biaxial positive, 2Vmeas. 35° 24' (Na). The refractive indices are: α ~ 2.035, β ~ 2.040, and γ ~ 2.085 (Na). Dispersion is strong, v >> r. The extinction is β//b, and α [001] = 20° (γ: [100] = 4°) in the obtuse angle β. H (Mohs) ≤ 2. D = 6.37 and calculated Dx = 6.40 g cm-3.Scotlandite occurs in cavities in massive baryte and anglesite, and is closely associated with lanarkite and susannite; it represents the latest phase in the crystallization sequence of the associated lead secondary minerals. The label locality of the specimen is the Susanna vein, Leadhills, Scotland.
Recent Advances in Ideas on the Origin of the Igneous Rocks of the Tertiary Igneous Province—Introduction
Authors: Walsh J. N. 
Published: December 2006

The first five papers of this issue of the Mineralogical Magazine have as a common theme Tertiary Igneous Geology. In May 1983 the Society held a thematic meeting on the igneous rocks of the Tertiary Province and from this has followed a collection of papers, grouped here together for convenience. The range of topics covered is broadly based and the papers demonstrate the extent of current research activity in the area.All readers of the Magazine will be aware of the extent of the contribution made to igneous petrology and geochemistry by work done on the Tertiary Igneous Province. The Tertiary age of the igneous rocks had been recognized from work during the last century by Sir Archibald Geike and Professor J. W. Judd.
Hydrothermal Sr contamination of the Dippin sill, Isle of Arran, Western Scotland
Authors: Dickin A. P. , Henderson C. M. B. , Gibb F. G. F. 
Published: December 2006

AbstractThe Dippin sill, which is emplaced into the Triassic sediments of SE Arran, is an alkaline basic sheet which displays pronounced hydrothermal alteration. The 40-m-thick sill has suffered pervasive contamination with radiogenic Sr, introduced from the Triassic sediments by hydrothermal fluids. Stable isotope measurements suggest that fluids were of meteoric origin, but were restricted to a small closed-system circulation. Initial 87Sr/86Sr ratios in the sill were raised from an original value of 0.7032 to a maximum of 0.7091, contamination being especially pronounced near the contacts at Dippin Head itself (localities 12 and 14) and in a drill core section through the sill above Dippin. Hydrothermal Sr was incorporated into an early-formed high-CaO, high-Sr analcime, which replaced unstable high-silica nepheline in interstitial patches. However, this high-CaO analcime, along with plagioclase, was later replaced by a low-CaO, low-Sr analcime, allowing Sr leaching from the margins of the sill. Hydrothermal fluids are thought to have migrated up to 1 km laterally, up the dip of the sill, mainly via tension joints forming in the cooling intrusion. Pooling of hot fluids at the upper end of the sill probably raised water/rock ratios in this region and allowed greater Sr contamination during mineralogical alteration. The undersaturated mineralogy of the sill accounts for its pervasive hydrothermal Sr contamination, which contrasts markedly with the relatively undisturbed Sr isotope compositions of Hebridean granites involved in hydrothermal systems.
Myggbukta and Kap Broer Ruys: the most northerly of the East Greenland Tertiary igneous centres(?)
Authors: Upton B. G. J. , Emeleus C. H. , Beckinsale R. D. , Macintyre R. M. 
Published: December 2006

AbstractThe Myggbukta Complex is a shallowly dissected central volcano superimposed on the early Tertiary Plateau Basalts of NE Greenland. This, and the Kap Broer Ruys centre, 30 km to the east, appear to be the most northerly central complexes of the North Atlantic Tertiary Province. The Myggbukta Complex comprises a suite of extrusions and minor intrusions ranging from picritic basalt to potassic rhyolite: most of the suite appears related by relatively low pressure (< 10 kbar) crystal fractionation. A small rise in initial 87Sr/86Sr (0.70593) with silica content is attributed to minor contamination through crustal anatexis. A basic dyke-swarm associated with the complex, precedes it and shows more limited differentiation. The basalts of the dyke-swarm and the Myggbukta Complex are genetically intimately related to the lavas forming the upper part of the earlier plateau basalt succession (UPLS). It is proposed that a large shield volcano developed some 100 km west of the developing spreading centre (Mohns/Aegir ridge), of which the UPLS, the dyke-swarm and the Myggbukta Complex represent three successive evolutionary stages. A generalized increase in differentiation through time can be recognized from one stage to the next. The acid intrusions of the Kap Broer Ruys area are probably also largely residues of basalt fractionation like their Myggbukta counterparts. However, higher initial 87Sr/86Sr ratios (0.70625–0.71034) imply a greater degree of crustal contamination.
Mixing of supernatant and interstitial fluids in the Rhum layered intrusion
Authors: Young Iain M. 
Published: December 2006

AbstractAn alternative explanation for the occurrence of chrome-spinel layers in the Eastern Layered Series of the Rhum intrusion is suggested by extreme concentrations of chrome-spinel in small-scale structures in the layer at the unit 7–8 boundary (Brown, 1956). These take the form of downward pointing cones several centimetres across and deep, and lined or wholly filled with chrome-spinel; lamination in the underlying allivalite exhibits quaquaversal dips around these cones. By comparing these structures to fluid escape structures in clastic sediments, it is proposed that spinel is the product of mixing and reaction of upward moving interstitial liquid and more primitive liquid newly emplaced in the chamber. Further evidence for the presence of a second liquid during spinel crystallization is provided by spherical silicate inclusions within spinel grains. Complex zoning in feldspars in the underlying allivalite suggests that the newly emplaced primitive liquid was able to penetrate the crystal mush on the intrusion floor.