bluuebunny/crossref_metadata_2025 huggingface dataset:
A metallographie study of some iron
meteorites of high nickel content
Authors: Axon H. J. , Smith P. L.
Published: December 2006

A metallographic investigation of macro-
and microstructure, supported in some instances by
microprobe examination, has been made on a number
of nickel-rich iron meteorites from the British
Museum Collection. Monahans, Wiley, Cowra, and
Deep Springs are considered together as plessitic
irons rather than ataxites, whilst Morradal shows
an unusual and coarse plessitic structure that has
been altered by pre-terrestrial shock and
reheating. Cape of Good Hope, Hoba, Tlacotepec,
and Chinga show chemical and structural
similarities and are discussed together, as are
Weaver Mountains, Klondike, and Warburton Range.
Meteorites considered separately include Kokomo,
Piñon, Shingle Springs, South Byron, San
Cristobal, Lime Creek, and Santa Catharina.
Particular attention is paid to the presence of
sulphides and of phosphorus-containing phases and
their influence on the formation of the macro- and
microstructure of these meteorites. Patches of
oriented sheen form a macroscopic feature of the
Cape of Good Hope group of irons and this effect
is considered in relation to details of the
microstructure. Attention is drawn to the fact
that in Cowra, Piñon, Weaver Mountains, South
Byron, and Morradal the troilite appears to have
been remelted and dispersed by a shock event that
operated at a temperature sufficiently high to
allow obvious shock damage to anneal out of the
metal phases.
Rameauite and agrinierite, two new hydrated complex uranyl oxides from Margnac, France
Authors: Cesbron F. , Brown W. L. , Bariand P. , Geffroy J.
Published: December 2006

Two new hydrated uranyl oxides from Margnac, France, are described. Rameauite, K2O.CaO.6UO3.9H2O, occurs with uranophane and calcite on pitchblende, agrinierite, 2(K2O, CaO,SrO). 6UO3.8H2O, with uranophane in small cavities in ‘gummite’.

Rameauite is monoclinic with a 13·97, b 14·26, c 14·22 Å, β 121° 1′±5′; the space group is C2/c. The principal d-spacings, with hkl values and relative intensities, are: 7·12, 020, vvs; 3·566, 040, vs; 3·495, 40, vvs; 3·473, 202, vs; 3·185, 22, vs; 3·139, 42, vvs; 2·993, 400, vvs; 2·495, 44, ms. Measured density 5·6 g.cm−3. The orange crystals are twinned on {100}, flattened on {010} and elongate parallel to [001]; there is a good {010} cleavage. α ‖; [010], γ: [001] 4 to 6° in the obtuse angle β, 2Vα 32°; the two principal reflectivities for yellow light on {010} are 10·6 and 10·4%. The main endothermic peaks on the d.t.a. diagram are at 95, 130, and 170 °C (loss of water), and at 1050 °C (loss of oxygen).

Agrinierite is orthorhombic with a 14·04, b 24·07, c 14·13 Å; space group Cmmm on the assumption of holohedral symmetry. Measured density 5·7 g.cm−3. The principal d-spacings are 7·08, 002, vvs; 6·05, 220, ms; 3·516, 400 & 332, s; 3·485, 062 & 260, vs; 3·153, 204 & 134, vs; 3·128, 262, vvs; 2·023, 660, s. The orange crystals are tabular on {001} with pseudo-hexagonal section bounded by the trace of (010), and show sector twinning on {110} as in billietite; there is a good {001} cleavage. The two reflectivities for yellow light on the face (001) are 12·0 and 11·2 %, corresponding to a refractive index of about 2. α ‖ [001], γ ‖ [010], 2Vα 55°. The principal endothermic d.t.a. peaks are at 163 °C (loss of water) and 1060 °C (loss of oxygen).

Rameauite is named after J. Rameau and agrinierite after H. Agrinier. The original specimens are deposited in the Mineralogical Collection of the University of Paris VI.
The new mineral insizwaite (PtBi2) and new data on niggliite (PtSn)
Authors: Cabri L. J. , Harris D. C.
Published: December 2006

Insizwaite from Waterfall Gorge, Insizwa, is a new mineral with the composition Pt1·00Bi1·35Sb0·57. The name is for the locality and is to be applied to the end member PtBi2. The analysed material is an antimonian variety. The mineral is cubic, the unit-cell for the antimonian variety has a 6·625 (2) Å, probable space group Pa3, calc. D 12·8 g/cm3. The strongest lines on the X-ray diffraction powder pattern are: 2·96 (8) 210; 2·70 (8) 211; 2·34 (5) 220; 1·99 (10 311; 1·774 (7) 321; 1·433 (5) 421; 1·277 (6) 511, 333; 1·171 (6) 440; and 0·862 (7) 731. Under reflected light the mineral is white (in air and in oil) and is isotropic. Reflectance measurements at 470, 546, 589, and 650 nm gave 61·1, 60·0, 60·6, and 61·7 %. Micro-indentation hardness values range from 488 to 540 (av. 519) kg/mm2 with a 25 g load.

New data are presented for niggliite from the type locality and for synthetic PtSn.
A differentiated ultrabasic sheet on Sgurr Dearg, Isle of Skye
Authors: Gibb Fergus G. F.
Published: December 2006

The field relations, mineralogy, and petrography of a small Tertiary ultrabasic sheet are briefly described. Chemical analyses show that compositional variations exist within the intrusion and electron-probe analyses demonstrate that optically undetectable zoning is present in the olivine. Throughout the intrusion, which is composed primarily of forsteritic olivine, calcic plagioclase, and clinopyroxene, there is a differential distribution of olivine. This distribution is attributed to flow differentiation during intrusion followed by gravitative sinking of olivine crystals.
Natural and laboratory α-particle irradiation of diamond
Authors: Vance E. R. , Milledge H. J.
Published: December 2006

To produce a lattice expansion readily detectable by conventional X-ray photographic means in α-irradiated diamond, a dose of order 1018α.cm−2 is required. Such a dose could be produced by pitchblende in ∼2 × 108 yr. and a previously reported lattice expansion in a natural diamond could therefore have occurred by long-term contact with a radioactive material. α-particle doses greater than ∼1014 cm−2 produce observable green colouration on the surface of an initially colourless diamond.
Iron—titanium oxide minerals in the Series,
Kap Edvard Holm, East Upper Layered
Greenland
Authors: Elsdon R.
Published: December 2006

Electron-probe data are presented for
coexisting magnetite and ilmenite from seven
gabbro cumulates and a gabbro pegmatite, and bulk
FeO-Fe2O3-TiO2
analyses for ten magnetite-ilmenite assemblages.
The oxides equilibrated at 580 to 720 °C and
oxygen fugacities of 10−15·0
to 10−20·5 bar. Late-stage
alteration, associated with growth of hydrothermal
silicates, resulted in the breakdown of ilmenite
to rutile and the dissolution of magnetite. Higher
levels in the intrusion equilibrated at lower
temperatures than deeper levels. All features
described are consistent with the retention of the
initial water content of the magma within the
walls of the intrusion.
Biphosphammite: a second occurrence
Authors: Pryce M. W.
Published: December 2006

Biphosphammite,
NH4H2PO4,
recorded once as secondary powder in 1870, occurs
with bat guano in Murra-el-elevyn cave, 31° 20′
S., 126° 0′ E., Western Australia.

The mineral occurs as tapering tetragonal
prisms with pyramidal terminations, which are
colourless to light buff, very soft, water
soluble, contain fine syngenite inclusions, and
have D 2·04, ω 1·525,
ε 1·480 Space group.
,
a 7·4935 Å,
c 7·340 Å, six
strongest powder X-ray lines 3·75 Å (10) 200; 5·24
Å (9) 101; 3·02 Å (9) 112; 1·993 Å (8) 312,213;
2·65 Å (7) 220; 2·368 Å (7) 310,301. Partial
analysis of purest available material gave:
P2O5
51·1, K2O 14·2,
(NH4)2O
12·3, SO2 5·59,
Na2O 0·16, water-insolubles
0·81 per cent, remainder mainly CaO and
H2O. Calculated mineral
content is 88 % biphosphammite (62 %
NH4H2PO4,
38% isomorphous
KH2PO4),
11·5% syngenite, insolubles 0·81 % calc. total
100·3 per cent.

Material proposed to be neotype is
preserved at the Government Chemical Laboratories,
Perth, Western Australia.
Calcium sulphosilicate in lime-kiln wall
coating
Authors: Pryce M. W.
Published: December 2006

Green calcium sulphosilicate layers were
formed in lime-larnite-calcite wall coating in a
lime kiln at Rivervale, Western Australia. The
compound formed in the kiln flame area by the
combination of siliceous lime sand feed with
sulphur trioxide from the sulphurous oil
fuel.

The calcium sulphosilicate is orthorhombic
with a 10·183,
b 15·408,
c 6·825 Å, space group
Pcmn. Crystals are
[100] tablets or prisms elongated along
c, D 2·95, hardness 5,
streak pale green, decomposed by organic acids.
Optical properties α
1·632 = [001] blue, β
1·638 = [100] yellow-green
γ 1·640 yellow-green,
2Vα = 60°, dispersion
r >
v, X-ray powder lines:
2·855 (10) 032,202; 2·838 (7) 330,321; 3·35 (6)
012; 2·622 (6) 331; 2·571 (6) 060; 3·20 (5) 231;
1·962 (5); 1·899 (5); 1·896 (5); 1·372
(5).

Chemical analysis by P. Hewson gave:
SiO2 21·50,
Al2O3
1·83,
Fe2O2
0·50, CO2 0·49,
P2O5
0·23, CaO 57·19, MgO 0·35,
Na2O 0·22,
K2O 0·22, SrO 0·15,
Li2O 0·06,
SO3 16·71,
H2O+
0·28,
H2O−
0·10, others 0·04, total 99·87. On a water-free
basis the unit cell contains
Ca19.66
Mg0.17
Na0.14
K0.08
Sr0.03
Li0.08
approximately
4[Ca5(SiO4)2SO4]
and isostructural with silicocarnotite,
4[Ca5(PO4)2SiO4].
Type material is preserved at the Government
Chemical Laboratories, Perth, Western
Australia.
Wroewolfeite, a new copper sulphate hydroxide hydrate
Authors: Dunn Pete J. , Rouse Roland C.
Published: December 2006

Wroewolfeite is a new mineral from the Loudville lead mine in Loudville, Massachusetts, U.S.A. The mineral occurs as blue, monoclinic crystals, twinned on {001}, very similar in appearance to posnjakite and langite. It is formed as small isolated pinacoidal crystals (up to 1.0 mm) implanted on covelline and chalcosine. There are three cleavages of equal facility of production. The cell dimensions are a 6.058 Å, b 5.654 Å, c 14.360 Å, β 93° 28′, space group Pc or P2/c. The strongest diffraction lines (in Å) are 7.152 (100), 3.581 (70), 2.628 (35), 2.004 (30), 2.431 (20), 2.379 (20), 2.278 (20). Electronmicroprobe analysis gives CuO 64.22 %, SO3 16.48 %, water by difference 19.30 %. Empirical cell contents are Cu7.88(SO4)2.00(OH)11.76.(H2O)4.22 or Cu4(SO4)(OH)6.2H2O with Z = 2. Wroewolfeite is strongly pleochroic with a light blue, β deep greenish blue, and γ, medium greenish blue. Absorption β > γ ≫ α. The mineral is biaxial with α 1.637, β 1.682, and γ 1.694, 2Vα = 53° The name is for C. Wroe Wolfe, American crystallographer, educator, and philosopher.
Petrogenesis of the Tarr albitite—carbonatite complex, Sinai Peninsula
Authors: Shimron Aryeh Ervin
Published: December 2006

Large albitite bodies associated with explosive brecciation, fenite aureoles, intrusive carbonate rocks, olivine dolerites, and copper mineralization are described from the Dead Sea rift region in the south-eastern Sinai Peninsula. The main carbonate phases comprise breunnerite and dolomite with actinolite the main phase in the fenites. Field and isotopic evidence indicates that the intrusive carbonate rocks are of carbonatitic origin. The cogenetic, almost monomineralic main phases can be attributed to fractional crystallization and liquid immiscibility acting on a highly gascharged, slow-cooling gabbroic magma. The complex, which is probably of Cretaceous (or older) age, appears to be related to early continental separation along the Dead Sea branch of the African rift system. The porphyry-type copper deposits resemble others that are located along crustal accretion (Iceland) or subduction (Chile) zones.
Mercury in rocks and minerals of the Skaergaard intrusion, East Greenland
Authors: Dissanayake C. B. , Vincent E. A.
Published: December 2006

Mercury has been determined by radiochemical neutron-activation analysis in nineteen representative rocks from the Skaergaard intrusion and in the separated cumulus minerals of five. The chilled marginal gabbro contains 0.23 ppm Hg, values in the Layered Series rocks ranging from 0.07 to 0.34 ppm, in one exceptional case reaching 1.23 ppm Hg. There is a tendency for mercury to be more abundant in leucocratic than in average or melanocratic rocks at a similar horizon. Somewhat higher levels of mercury are found in the granophyric rocks at the top of the intrusion.

Apart from a weak and sporadic tendency to be preferentially enriched in plagioclase, the distribution of mercury between the various cumulus phases is fairly uniform and it is thought to occur as uncharged atoms mainly occupying spaces resulting from lattice defects and imperfections rather than in specific structural sites.

The distribution pattern of mercury in the intrusion appears to be determined by its high volatility and chemical inertness; no real evidence of any chalcophile character is observed.
Some aluminous clinopyroxenes from Vesuvius and Monte Somma, Italy
Authors: Rahman S.
Published: December 2006

Aluminous Ca-rich clinopyroxenes (5.95-7.63 wt % Al2O3) are next in abundance to leucite in the basic alkaline potassic lavas from Monte Somma and Vesuvius, Italy, and occur as phenocrysts (1 to 7 mm), micropbenocrysts (< 1 mm), and groundmass granules. Zoning of various types is a conspicuous feature in these pyroxenes. Optical and chemical data are presented and a comparison is made between these pyroxenes and similar ones from alkali basalts. It is known from published data that Al2O3 fluctuates strongly in the oscillatory zones of Vesuvian pyroxenes. This can be explained as due to temperature variation in the magma, to magma variation in silica content due to contamination, to oscillations in leucite precipitation, or to a combination of these factors. Of these three factors, oscillations in leucite precipitation, as it appears, would be more effective than the others since it would have a greater control over Si/A1 availability in the magma.
Garnets from the Upper Swat Hornblendic Group, Swat District, Pakistan. Part I: Garnets from gneisses and pegmatites
Authors: Ahmed Zulfiqar , Ahmed Shafeeq
Published: December 2006

Chemical analyses of eleven garnets from orthogneisses and related pegmatites, belonging to the Upper Swat Hornblendic Group, Pakistan, are presented along with the petrographic descriptions of the host rocks. The garnets show dominant almandine content, followed by grossular pyrope, spessartine, and andradite, in order of relative abundance. One garnet sample is different from the rest in having higher andradite and spessartine contents and higher refractive index, and is also different in habit. This is the first detailed study of garnets from Pakistan.
High-temperature homogenization behaviour of some sodic mieroperthites
Authors: Parsons Ian
Published: December 2006

While undergoing 'dry' homogenization at 980°C the 2̄01 X-ray reflections of sodic lowalbite- microcline microperthites show that phase compositions recapitulate (but in a reverse timesense) the unmixing history of ordered feldspars about a solvus with a critical composition near 26 mole per cent KAlSi3O8.
A garnierite with a high nickel content from Western Australia
Authors: Nickel E. H. , Bridge P. J.
Published: December 2006

The garnierite, which occurs in the oxide zone overlying a nickel sulphide deposit, consists of talc-like and serpentine-like components, with the former predominating. Chemical and electron-probe analyses give NiO contents ranging between 39.6 and 43.9 weight %.
Volatility of oxides from silicate melt and the origin of moldavites
Authors: Konta J. , MráZ L.
Published: December 2006

The volatilities of SiO2, Na2O, and Fe2O31increase with increasing thermal function within the range 1600 to 2100°C during the melting of a sandy-silty clay. The remaining melt is to some extent enriched in Al2O3, K2O, CaO, and MgO. Chemical analyses of the sandy-silty clay, of the glasses melted from the latter, of the silicate material evaporated and newly condensed and their correlation with increasing thermal function and bulk density of glasses, as well as with the hitherto known quantitative data on moldavites, testify to the fact that in moldavites evaporated and newly condensed silicate material substantially prevails over material that passed directly from a solid to a fluid state. Evaporation of the silicate material from the rocks of the impact crater caused a significant change in relations between major oxides compared to the original relations in the source rocks. Thus, the hypothesis that tektites are directly remelted rocks of the Earth's crust, based on over-all chemical similarities of tektites and some rocks in major oxides, appears incorrect.
A Mössbauer study of thermal decomposition of biotites
Authors: Hogg C. S. , Meads R. E.
Published: December 2006

The effect of heat treatment in air at temperatures from 200°C to 1000°C of two Cornish biotites has been studied using the M6ssbauer effect in 57Fe. One of the micas was also studied after heating in vacuo.

Progressive changes in the Mössbauer spectra of the materials after heat treatment can be correlated with the following processes: Oxidation of Fe2+ ions in isolated octahedral sites to give Fe3+ in the co-ordination Fe3+(OsOH); oxidation of Fe2+ ions in adjacent a-octahedral (cis OH−) sites to give Fe3+(O6); and oxidation of Fe z+ in adjacent a and b (trans OH−) sites to give either Fe3+(O5OH) or Fe3+(O6) depending on whether a shared hydroxyl group remains intact or otherwise (these processes occur at temperatures below 500°C Also, at higher temperatures, dehydroxylation of Fe3+(O5OH) to give more Fe3+ in the Fe3+(O6) configuration. Finally, in the temperature range 900 to 1000°C structural breakdown yielding α-Fe2O3 as the iron-containing phase.

The results and interpretation are in good agreement with thermogravimetric data and with a previous infra-red study. The mechanism of charge diffusion in the lattice during oxidation is discussed in the light of the results.
A new miniphotometer for teaching and routine work in ore microscopy
Authors: Tarkian M. , Stumpfl E. F. , Matthies H.
Published: December 2006

A simple and easy-to-use miniphotometer has been designed; the expense involved amounts to only a fraction of that required for large commercially available microphotometers.

The instrument can be employed for routine investigations and for teaching reflected light microscopy in conjunction with standard reflected light microscopes.

The reflectance of grains down to 50 μm size can be measured in white and monochromatic light employing continuous band and line interference filters. The systematic error does not exceed 1.5 % of the values measured. The only aspect that distinguishes the miniphotometer from larger instruments is the limitation of spot size. A comprehensive test programme including comparative sets of measurements on a Zeiss MPM spectral microphotometer has shown that the results obtained by both instruments coincide well.
Tacharanite
Authors: Cliff G. , Gard J. A. , Lorimer G. W. , Taylor H. F. W.
Published: December 2006

Tacharanite has been re-examined using electron microscopy and diffraction, analytical microscopy, X-ray powder and fibre rotation photographs, and other methods. The composition approximates to Ca12Al2Si18O69H36, and the X-ray diffraction patterns can be referred to anA-centred monoclinic pseudo-cell witha17·07,b3·65, c 27·9 Å, β 114·1°, Z = 1. In the true cellbis certainly, andaand c probably, doubled. Small, reversible changes in pseudo-cell parameters occur on heating below 200°C, and parameters found by electron diffraction differ slightly from those found with X-rays, presumably due to shrinkage on dehydration in the high vacuum of the electron microscope. An earlier report that tacharanite changes into a mixture of tobermorite and gyrolite on standing in air is not confirmed. Tacharanite shows some important resemblances to tobermorite, but there are also significant differences.
Chromite alteration in the Panton Sill, East Kimberley Region, Western Australia
Authors: Hamlyn Paul R.
Published: December 2006

In addition to the normal type of chromite alteration, an antipathetic form of alteration has been observed in the ultramafic zone of the Panton Sill, Western Australia. The chromites display margins of lower reflectivity related to a marked enrichment in MgO and Al2O3and depletion in Cr2O3, Fe2O3, and FeO, such that a spinellid of composition lying between the end members MgAl2O4and FeAlaO4is formed. The alteration is related to the formation of secondary spinel in the ground-mass during the hornblendization of primary silicates under metasomatic conditions accompanied by low oxygen activity.
Kaersutite-bearing gabbroic inclusions and the late dike swarm of Kangerdlugssuaq, East Greenland
Authors: Kent Brooks C. , Platt R. G.
Published: December 2006

The Kangerdlugssuaq late dike swarm, which strikes at a high angle to the well-known East Greenland coastal swarm, is described and chemical analyses presented. The basic members are characterized by a high potassium content. A variety of kaersutite-bearing gabbroic inclusions in one member of this swarm is described in detail and microprobe analyses of clinopyroxenes, amphiboles, plagioclases, sheet silicates, and spinel minerals are presented. On the basis of this evidence it is deduced that these inclusions derive from a cumulate sequence formed at depths of between 5 and 10 km beneath the Lower Tertiary land surface. It is likely that fractionation of such assemblages causes a transition, at relatively low pressure, from undersaturated to oversaturated compositions, but the products appear to be quantitatively minor.
Regional variation in the crustal abundance of minor elements: evidence from the granites of Sardinia
Authors: Hall A.
Published: December 2006

The granites of Sardinia have been analysed for copper, lead, and zinc, and each element has been found to show a regional variation. There is a close relationship between the copper and lead contents of the granites and the distribution of copper and lead mineralization in the island, but very little relation between the zinc contents of the granites and the distribution of zinc mineralization. This is attributed to a greater degree of lithophile character of zinc in the magmatic source region.
A sapphirine-cordierite-bronzite-phlogopite paragenesis from Namaqualand, South Africa
Authors: Clifford T. N. , Stumpfl E. F. , McIver J. R.
Published: December 2006

The rock composition and electron microprobe analyses of the five constituent minerals are presented for a sapphirine-cordierite-bronzite-phlogopite-spinel rock from Namaqualand, South Africa. These data are considered inrelation to experimental data and the mineralogy of certain associated rock types, and it is suggested that the sapphirine-bearing rock represents a metamorphic residuum (restite) after extraction of anatectic granitic liquid from an original argillaceous sediment.
The origin of the Kennethmont granite-diorite series, Insch, Aberdeenshire
Authors: Busrewil M. T. , Pankhurst R. J. , Wadsworth W. J.
Published: December 2006

The Insch granite-diorite complex of Aberdeenshire consists of acid and intermediate igneous rocks that are quite distinct from, and younger than, the differentiates of the Insch basic mass.

The main components of the complex include two types of uniform granite (one pink, one grey), and a variety of inhomogeneous dioritic rocks (diorite xenoliths in grey granite matrix, granodiorite with residual mafic inclusions, and more uniform diorite). Full chemical analyses for major and trace elements are presented for sixteen rocks representative of all types, together with initial 87Sr/86Sr ratios and rare-earth-element distribution patterns for a selection of samples. The pink granite is not chemically related to the remaining members of the complex. Comparison with chemical data for a range of basic igneous rocks of the Insch and Boganclogh basic masses discredits the hypothesis that the diorite rocks were produced by assimilation of any of these in the grey granite magma. A primary diorite magma is recognized as essential to the petrogenesis of the complex.
Leucite-Na-feldspar incompatibility: an experimental study
Authors: Gupta Alok K. , Edgar Alan D.
Published: December 2006

Phase relations at atmospheric pressure in the pseudobinary join KAlSi2O6 (Lc)-NaAlSi3O8(Ab) and in the pseudoternary join Lc-Ab-CaAl2Si2O8(An) indicate that leucite is in-compatible with Na-feldspar. In the former join leucite can exist with an alkali feldspar of maximum albite content Ab54. In the Lc-Ab-An join, leucite only coexists with ternary feldspars with high An contents (approximately An50). Under PH2O conditions leucites may only coexist with alkali feldspars even poorer in Ab than those found at atmospheric pressure. Rare occurrences of coexisting leucite and Na-feldspar in nature have probably not crystallized directly from a melt but may have formed by a process of alkali ion exchange; or they may be unstable assemblages. No support can be found for the suggestions based on thermochemical calculations that albite and leucite are compatible at high temperatures.
Mineralogy, chemistry, and origin of a concretionary siderite sheet (clay-ironstone band) in the Westphalian of Yorkshire
Authors: Curtis C. D. , Pearson M. J. , Somogyi V. A.
Published: December 2006

Concretionary siderite horizons are quite common in massive clay sequences. One such horizon, from the Westphalian of Yorkshire, has been studied in detail. Two iron-rich carbonate minerals occur together although they cannot be distinguished in thin section on account of very fine grain size. One is much richer in magnesium (pistomesite) than the other (siderite). The latter is rela-tively rich in manganese and the heavier stable carbon isotope 13C whereas the former carbonate is richer in calcium and 12C. The most important iron source is thought to have been hydrated iron oxides originating in soils. Much of the carbonate carbon started as organic molecules. The siderite appears to have formed earlier than the pistomesite. The stratiform character of these deposits appears to reflect siltier horizons in the mudstones, which presumably channelled pore water migration during compaction. This is probably why such carbonate horizons were formerly believed to be of simple sedimentary rather than diagenetic origin.
On 'winchite' from the original locality at Kajlidongri, India
Authors: Nayak V. K. , Leake Bernard E.
Published: December 2006

A new analysis of the violet amphibole from the original locality where winchite came from agrees with another recent analysis in differing substantially from the original winchite composition and is (K0·17Na2·10Ca0·23)(Al0·19Ti0·00Fe31·27Fe20·01Mn0·07Mg3·34)Si8·01O22·05(OH)1·95. It is essentially a magnesio-arfvedsonite. Although it is possible that the original analysis was unreliable, evidence is given to support the alternative view that there is a wide range of blue alkali and soda calcic amphibole compositions at Kajlidongri and the name winchite should be restricted to compositions between ferri-winchite CaNaMg5Fe3+Si8O22(OH,F,Cl)2 and alumino-winchite CaNaMg5Al Si8O22(OH,F,Cl)2. X-ray, density, and optical data on the analysed mineral are given.
Synthesis of K2SiSi3O9 with silicon in 4- and 6-coordination
Authors: Kinomura N. , Kume S. , Koizumi M.
Published: December 2006

Two kinds of vitreous material with composition K2GeSi3O9 and K2Si4O9 were treated under conditions of high temperature and pressure. The X-ray diffraction patterns of the products were similar to that of K2TiSi3O9, which has the wadeite, K2ZrSi3O9, structure.

A natural crystal of K-feldspar was also treated under the same conditions. The product was found to consist of three phases, coesite, kyanite, and the above-mentioned K2Si4O9. Since Zr ions in wadeite are in a 6-coordinated site, one-quarter of Si ions in K2Si4O9 are considered to be in 6-coordination. This is the first silicate in which Si ions occupy sites of 4- and 6-coordinations in one crystal at the same time.
Fluorine and chlorine in peralkaline liquids and the need for magma generation in an open system
Authors: Bailey D. K. , Macdonald R.
Published: December 2006

Fluorine, chlorine, zinc, niobium, zirconium, yttrium, and rubidium have been deter-mined on fifteen obsidians from Eburru volcano (Kenya Rift Valley), spanning the range from pantel-leritic trachyte to pantellerite. All pairs of elements show positive correlation coefficients, ranging between 0·769 and 0·998, but with most values better than 0·900. In spite of some very high correlations, only two of the twenty-one best-fit lines pass near the origin of the Cartesian coordinates. Linear distributions are found within two separate groups of elements: F, Zr, Rb; and Cl, Nb, Yt. Zn behaves in general as a member of the second group but seems to be subject to an additional variation. When an element from the fluorine group is plotted against one from the chlorine group the resulting pattern is non-linear. Therefore, although the elements in both groups would generally be considered ‘residual’ (partition coefficients between crystals and liquid approaching zero) there are clearly detectable differences in their variation, and hence their behaviour.

Major-element variations in the obsidians are such that a vapour (fluid) phase would be needed to account for any magma evolution. The trace-element patterns are also impossible by closed-system crystal fractionation and suggest that this fluid may have been rich in halogens, with the metallic elements forming preferred ‘complexes’ with either F or Cl. The F-Zr-Rb ‘complex’ also varies quite independently of the important major oxides (e.g. A12O3) in the rocks. In the case of Rb this is but one aspect of a more significant anomaly, in which there is no sign of any influence of alkali feldspar (which partitions Rb) in the variation. This is remarkable because trachytes and rhyolites have normative ab+or > 50 %, and any evolutionary process controlled by crystal ⇋ liquid interactions must be dominated by the melting or crystallization of alkali feldspar. The results on the Eburru obsidians show that if they are an evolutionary series then either, the process was not crystal ⇋ liquid controlled, or that any such process has been overriden (or buffered) by other processes that have superimposed the observed trace-element patterns. In the latter event, the buffering phase may have been a halogen-bearing vapour.

The same considerations must apply to other pantellerite provinces where Rb appears to have behaved as a ‘residual’ element.
Iraqite, a new rare-earth mineral of the ekanite group
Authors: Livingstone A. , Atkin D. , Hutchison D. , Al-Hermezi H. M.
Published: December 2006

Iraqite, a new mineral of the ekanite group from northern Iraq, has the composition (Ln1·33 Th0·66x0·15) (K1·07y0·93) (Ca3·49 Ln0·35 Na0·16) (Si15·69 Al0·27) (O39·93 F0·07) where x = U, Pb, Zr, Fe, Mg, and Cu, and y is presumed to be vacant sites. It occurs in granite in contact with dolomitic marble. The colour is pale greenish yellow; H 4½ Dcalc 3·28 and Dmeas 3·27 (Berman balance), both corrected for minor impurity and non-structural water. Optically it is uniaxially negative with ω 1·590 and ε 1·585 though some sections show anomalous extinction up to 7°. Space group is P4/mcc with a 7·61±0·01 and c 14·72±0·02 Å. Strongest lines of the indexed powder pattern are 5·28(100), 3·31(100), 2·64(100), 7·36(80), 3·38(80), 3·40(60), 2·7(40), 7·62(30). Thermal data are given.
Nickeloan pyroaurite from Leslie, Aberdeenshire
Authors: Wilson M. J. , Cradwick P. D. , Berrow M. L. , McHardy W. J. , Russell J. D.
Published: December 2006

A nickel-bearing mineral belonging to the pyroaurite-sj~Sgrenite group has been found in a serpentinite rock near the village of Leslie, Aberdeenshire. X-ray powder diffraction data and electron-probe microanalysis indicate that the mineral has a three-layer rhombohedral structure with a probable formula near (OH)13CO3.4H2O. The mineral can therefore be described as nickeloan pyroaurite. It decomposes readily in mildly acid conditions and if inherited by serpentinite-derived soils could well be an important source of plant-available nickel.
The geochemistry of biotites from granites of northern Portugal with special reference to their tin content
Authors: Neiva A. M. R.
Published: December 2006

Biotites from a number of granites have been analysed for major oxides and a wide range of trace elements. Their compositions are found to be typical of biotites from granite and to show element fractionation in presumed differentiation series. Estimates are made of the fugacity of oxygen and water during the crystallization of the granites. PH2O is found to increase slightly through the differentiation series, and fO2, for a temperature of 700°C is estimated to be between 10−18 and 10−12. Tin mineralization is connected with the igneous rocks and the relationship of tin in the micas to the rock compositions is described and the factors controlling the distribution of tin are discussed. The biotites have only up to 21 % of the tin of the granites. In general Sn increases in the biotites with decreasing temperature of equilibration and with increase in the degree of albitization of the granites. High Sn in biotites seems to be an indicator of potential mineralization.
A note on some Dalradian stilpnomelanes and their oxidation
Authors: Graham Colin M.
Published: December 2006

The widespread ferristilpnomelane in Dalradian metabasites of the south-west Scottish Highlands has usually formed by secondary oxidation of primary ferrostilpnomelane, probably during weathering. Ferrostilpnomelane oxidizes readily in polished thin sections open to the atmosphere over a period of months, and microprobe examination of the resulting ferristilpnomelane suggests a change in the role of potassium in the structure during oxidation.
The chemistry of riebeckites of Massachusetts and Rhode Island
Authors: Lyons Paul C.
Published: December 2006

Four new chemical analyses are reported for riebeckites of the hypersolvus granites of Massachusetts and Rhode Island. Riebeckites of southern New England are enriched in Li+, which appears to substitute for Fe2+, with additional Na+ coming in to compensate for the charge imbalance.
A metallographic and petrological study of metal–silicate fragments in the > 1 mm size range from lunar soil 14162,80
Authors: Agrell S. O. , Axon H. J. , Goldstein J. I.
Published: December 2006

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.
Kornerupiue in metasomatic zones, Strangways Range, Central Australia
Authors: Woodford P. J. , Wilson Allan F.
Published: December 2006

The first known occurrence of kornerupine in Australia is described. The mineral is a minor component of a phlogopite-rich garnet-corundum-spinel metasomatic zone, which cuts mafic and ultranlafic spinel-plagioclase-orthopyroxene-hornblende rocks. The kornerupine-bearing assemblage was formed during the second major metamorphic episode that affected the terrain, probably under low-grade granulite or upper amphibolite facies conditions. Kornerupine appears to have formed at significantly lower levels ofP-Tthan those reached in the terrain during the peak of the second granulite metamorphism.
Ænigmatite from an Ægirine—Riebeckite granite, Liruei Complex, Nigeria
Authors: Borley G. D.
Published: December 2006

Ænigmatite occurs as a trace constituent of the Ægirine-Riebeckite Granite of the Liruei Complex, Younger Granite Province of Nigeria. It is enriched in Ti and Mg and depleted in Si, Al, and Ca relative to many other ænigmatites. Relative to coexisting ægirine and arfvedsonitic riebeckite it is enriched in Ti and depleted in Fe3+. Conditions required for formation of the mineral appear to have been high Ti concentration in a peralkaline magma of low T and fo2. The composition of the Nigerian ænigmatite confirms that there is only limited miscibility between rhönite and aenigmatite although in certain circumstances the two may have a paragenetic relationship.
The halotrichite group: the crystal structure of apjohnite
Authors: Menchetti S. , Sabelli C.
Published: December 2006

Apjohnite, MnAl2(SO4)4·22H2O, is monoclinic, space group P21/c, a 6·198 (2), b 24·347 (4), c 21·266 (4) Å, β 100·28 (3)° and Z = 4. The crystal structure was determined by means of direct methods applied to X-ray data collected with a single-crystal diffractometer. At the end of the refinement, performed with least-squares method, the R index was 0·039.

The SO4 tetrahedra, Al(H2O)5 octahedra, and MnO(H2O)5 octahedra are connected by a hydrogen bonding system; the only direct connection between polyhedra is by sharing of an oxygen between S(4) and Mn. In the asymmetric unit there are twenty-two water molecules, five of which lie in channels of the structure and are not linked to the cations but only to ligand water oxygens by means of hydrogen bonds.

Powder data indicate a close structural relationship between apjohnite, halotrichite, and pickeringite.
Crystallinity among some hydrous aluminium phosphates
Authors: Duncan McConnell
Published: December 2006

Compositions of nine hydrous aluminium phosphates are considered with respect to the AI, P, and H contents per 8 oxygens, and it is suggested that when the ratio (Al.P)/H is less than 0·11 (or (Al.P2)/H2 is less than 0.01) such compositions do not crystallize. Examples are bolivarite and evansite.
The Suisnish layered dyke
Authors: Parslow G. R.
Published: December 2006

A minor picritic body at Suisnish Point, Isle of Skye, is described. The mass has a dyke-like form, and is rhythmically layered. Cryptic layering, however, is absent. From a study of the field relations, contacts, metamorphic aureole, and other physical features, it is concluded that the mass crystallized in situ (i.e. it is a true dyke) and is not an upfaulted block of pre-existing igneous rock. The main physical and chemical features of the layered units and their mineralogy are described. The problems of generating horizontal rhythmic layers in a relatively small, essentially vertical, planar intrusion are discussed. It is concluded that the surrounding country rock was maintained at a moderate temperature during, and after, intrusion of the picritic magma and that this allowed a combination of gravity settling and magma flow currents to produce a cumulate rock with characters normally only observed in much larger intrusions.
Chromite-chlorite intergrowths in peridotite at Chimwadzulu Hill, Malawi
Authors: Haslam H. W. , Harding R. R. , Tresham A. E.
Published: December 2006

Chromiferous spinel and chlorite are associated and sometimes intergrown in serpentinized peridotites at Chimwadzulu Hill. The peridotites probably crystallized from a melt under the conditions of the spinel-lherzolite facies (O'Hara, 1967) in which the stable aluminous phase is spinel. The spinel that formed was probably a chromite with some Al2O3 and MgO. At lower temperatures aluminous spinel is unstable in the presence of olivine and orthopyroxene, chlorite being the stable aluminous mineral. It is thought that the chlorite crystallized under the conditions of medium-grade metamorphism that prevailed when the rocks were emplaced, and at the same time the spinel recrystallized, depleted in Al2O3 and MgO and correspondingly enriched in FeO, Fe2O3, and Cr2O3, giving rise to the observed chromite-chlorite association.
Zoned, birefringent garnets from Thera Island, Santorini Group (Aegean Sea)
Authors: Murad Enver
Published: December 2006

A garnetite that occurs locally in phyllitic schists exposed by the Santorini caldera consists mainly of euhedral garnet crystals showing alternating isotropic and birefringent lamellae. X-ray diffraction revealed two garnets with unit cell dimensions a of 12·052±0·002 and 11·984±0·005 Å, corresponding respectively to almost pure andradite and a granditic phase. Mean compositions determined by microprobe analysis are An97Sp1Alm2 for the isotropic and about An63Gr33Sp1Alm3 for the birefringent layers.

The garnets are deduced to have been produced mainly by thermal metamorphism of the schists. Although cyclic variations in the composition of circulating fluids could have brought about the zoning, this may just as well be the result of temperature fluctuations, individual garnet compositions being indicative of the respective formation temperature.
The Lodran meteorite and its relationship to the ureilites
Authors: Bild Richard W. , Wasson John T.
Published: December 2006

Lodran is a unique meteorite consisting of roughly equal amounts of metal, olivine, and pyroxene with minor amounts of sulphide, chromite, phosphide, chrome-diopside, and a new phase with a composition close to (K,Na)AlSi5O12. Zähringer reported planetary-type rare gases in both the metal and silicates, suggesting a primitive nature. The pyroxene composition is Fs13.8with little variation. Olivine composition averages Fa12.6, but varies at least ±20 % both among grains and zoned within single grains; only the Fe-rich olivine is in equilibrium with the pyroxene. The metal probably cooled rapidly (700 K/Myr) at high temperatures and slower (30 K/Myr) at lower temperatures. Two compositional populations of chromite are found.

A model for the formation of Lodran includes three steps: Formation of large olivine, pyroxene, and metal grains, with the trapping of small olivine inclusions in pyroxene and pyroxene in olivine. Equilibration and recrystallization of olivine, pyroxene, and metal, loss of alkalis and Ca; this probably occurred in a parent-body setting. And incorporation of reducing materials and mild reheating sufficient to produce the zoning in the olivine but not enough to re-equilibrate the pyroxene.

Phase compositions and rare-gas concentrations in ureilites are similar to those in Lodran. In some respects Lodran appears to be a metal-rich ureilite, but the higher Fe/(Fe+Mg) ratios in the latter (Fa 21 olivine) suggest origin on separate parent bodies.

The Harvard University meteorite is a mesosiderite and not closely related to Lodran.
Julgoldite, new data and occurrences; a second recording
Authors: Livingstone A.
Published: December 2006

Two new occurrences, in quartz dolerite, are reported for julgoldite. Physical and chemical data is presented together with indexed powder data for fifty-five reflections, fifteen of them additional to those previously reported. The julgoldite infra-red spectrum possesses the same configuration as that of an epidote or clinozoisite but with large peak shifts due to the high iron content.
Compositional range of P2/n omphacite from the eclogitic rocks of central Shikoku, Japan
Authors: Yokoyama Kazumi , Banno Shohei , Matsumoto Takeo
Published: December 2006

The lattice types of omphacite-diopside series clinopyroxenes were determined for 9 Japanese, 2 Norwegian, and 1 South African samples. The boundary between the compositional ranges of P and C lattice clinopyroxenes lies at about 14·5 wt. % CaO in Japanese and Norwegian samples, and the compositional gap between them is very small, if it exists. The South African omphacite has C-lattice in the compositional range of P lattice omphacite in metamorphic eclogites. These data combined with the reported electron microscope studies suggest that the omphacite—diopside series clinopyroxene has a C lattice structure above 3 to 400°C and very slow cooling after regional metamorphism is responsible for the transition to the ordered structure with P lattice symmetry.
The origin of scoriaceous rock associated with dacitic ignimbrite in the Mirannie-Mount-Rivers district, New South Wales, Australia
Authors: Nashar Beryl , White Noel C.
Published: December 2006

From field and petrographic evidence, some scoriaceous rock from the upper ignimbrite horizon of the Mount Rivers Volcanic Member of the Carboniferous Dyrring Formation in the Mirannie-Mount-Rivers District, New South Wales, Australia, is believed to have a recent origin.

By heating unaltered dacitic ignimbrite in a furnace it was possible to produce in the temperature range 600-1230°C changes in the rock similar to those observed in specimens of scoria collected in the field. Thus a temperature range for the alterations was established. Two possible sources of heat axe suggested as being responsible for the production of the scoriaceous rock, namely a bush fire and a lightning strike, with a preference for the former.
Crystallization trends of pyroxenes from the alkaline volcanic rocks of Tenerife, Canary Islands
Authors: Scott P. W.
Published: December 2006

The alkaline volcanic rocks of Tenerife comprise a compositionally continuous series of ankaramites, alkali basalts, trachybasalts, trachyandesites, trachytes, phonolites, and peralkaline phonolites. Ca-rich pyroxenes occur as phenocrysts throughout the series. They show a limited range of composition from diopside and Ti-rich samite in the basic and intermediate rocks, to sodic sahlite in some phonolites. Features of both the sahlite-aegirine and sahlite-hedenbergite trends are present. Sodic ferrosahlites occur as xenocrystal 'green cores' in phenocrysts from some basic and intermediate rocks. The latter are associated with kaersutite xenocrysts and are similar to pyroxenes in some plutonic xenoliths from Tenerife. During the formation of the 'green cores' conditions were more reducing allowing pyroxene compositions to extend through the range sahlite-hedenbergite.

Aegirine-angite and Ti-rich aegirine are present in the groundmass of some phonolites and in pyroclastic boulders of nepheline syenite. The aegirines are associated with magnesioarfvedsonite and aenigmatite, and it is considered that they crystallized under conditions of low oxygen fugacity.
An occurrence of eudialyte and manganoan pectolite in a phonolite dyke from south-eastern Queensland
Authors: Carr Graham R. , Phillips Evan R. , Williams P. R.
Published: December 2006

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
Chemistry of ilmenites crystallized within the anhydrous melting range of a tholeiitic andesite at pressures between 5 and 26 kb
Authors: Thompson R. N.
Published: December 2006

Microprobe analyses of eight ilmenites, a titaniferous magnetite, and a rutile are presented. They were synthesized at pressures from 5 to 26 kb and temperatures between 1075 and 1225°C in the anhydrous melting interval of a tholeiitic andesite from the Snake River Plain, Idaho, U.S.A. Both the Fe/Ti distribution between coexisting ilmenite and titanomagnetite at 11 kb/1075°C and the low calculated Fe3+ contents of the other ilmenites confirm previous suggestions that the fo2 in these experiments was buffered by graphite capsules to values near those generated by the wüstitemagnetite assemblage. Mn in the ilmenites (0·30-0·51% MnO) shows moderate negative correlations with both the pressures and temperatures of their formation, whilst Al (0·41-1·06 % Al2O3) shows poor positive correlations with these parameters. In contrast, the only significant trend shown by Mg in the ilmenites (2·09-5·26 % MgO) is with the position of each experimental run in the melting interval of the lava. Mg/(Mg + Fe2+) of the ilmenite decreases during equilibrium crystallization at a given pressure and appears to be controlled solely by Mg/Fe2+ distribution amongst the coexisting ferromagnesian minerals and interstitial liquid (glass).
Gmelinite and herschelite from the Ilímaussaq intrusion in South Greenland
Authors: Karup-Møller S.
Published: December 2006

Hypogene alteration of ussingite from the southern part of the Ilimaussaq intrusion in South Greenland has resulted in the formation of three associations: gmelinite-apophyllite, gmeliniteherschelite- earthy-natrolite, and earthy natrolite alone. Ossingite reacted with late magmatic fluids, producing the secondary minerals either byin situreplacement of the ussingite or in cavities, which may be up to 3 cm across.