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The Çaldag Ni-Co deposit is characterized by a reddish brown oxide lateritic regolith, containing residual Ni deposit formed by the intense tropical weathering of peridotites. Nickel--Co ore is associated with transported ferricrete during the late Paleocene--middle Eocene, represented by colloform Fe oxides and residual lateritization during the Oligocene. The lateritic regoliths are developed over dunitic ultramafic rocks and consist mainly of smectite, berthierine, kaolinite, gypsum, pyrite, takovite, and pecoraite. These units were examined using polarized-light microscopy, X-ray diffraction, scanning and transmission electron microscopy, and geochemical methods. Mineralogical zonation from the base of the profile upwards has the following zones: ultramafic bedrocks, serpentinized ultramafic rocks (saprock), saprolite, carbonate- and sulfide-bearing zone, ferruginous saprolite zone, and silcrete. In addition, Fe oxides, smectite and opal-CT, and quartz increase towards the surface, whereas olivine, pyroxene, and serpentine decrease upwards in response to chemical weathering. Nickel-Co mineralization associated with Fe oxides and smectitic clays formed under wet and dry conditions, respectively, as a result of an increased [Fe.sub.2][O.sub.3] + [Al.sub.2][O.sub.3] + Ni + Co/MgO ratio. Field observations and mineralogical and geochemical analyses reveal that the smectite formed under basic conditions was controlled by multistage chemical weathering of ultramafic and volcanic rocks and by the concentrations of Si, Al, Fe, and Mg. Locally, concentrations of S in conjunction with Fe and Ca resulted in precipitation of goethite-hematite, gypsum, and pyrite in dissolution voids in association with smectite under acidic conditions that developed in a well-drained system. Le gisement de Ni-Co de Çaldag est caractérisé par un régolithe latéritique oxydé brun rougeâtre contenant des dépôts de Ni résiduel formés par la météorisation tropicale intense de péridotites. Le minerai de Ni-Co est associé à une croûte ferrugineuse transportée durant le Paléocène tardif--Éocène moyen, représentée par des oxydes de Fe colloformes et une latérisation résiduelle durant l'Oligocène. Les régolithes latéritiques se sont formés sur des roches ultramafiques dunitiques et sont principalement composés de smectite, de berthierine, de kaolinite, de gypse, de pyrite, de takovite et de pécoraïte. Ces unités ont été examinées par microscopie à lumière polarisée, diffraction X, microscopie électronique à balayage et à transmission, et par des méthodes géochimiques. La zonation minéralogique de la base du profil vers le haut présente les zones suivantes : des roches ultramafiques du socle, des roches ultramafiques serpentinisées (saprock), des saprolites, une zone à carbonates et à sulfures, une zone à saprolite ferrugineuse et une silcrète. De plus, les abondances des oxydes de Fe, de la smectite et de l'opale-CT, ainsi que du quartz augmentent vers la surface, alors que celles de l'olivine, des pyroxènes et de la serpentine diminuent vers le haut en raison de l'altération chimique météorique. La minéralisation en Ni-Co associée aux oxydes de Fe et aux argiles smectitiques s'est formée dans des conditions humides et sèches, respectivement, des suites de l'augmentation du rapport [Fe.sub.2][O.sub.3] + [Al.sub.2][O.sub.3] + Ni + Co/MgO. Les observations de terrain et les analyses minéralogiques et géochimiques révèlent que la formation de la smectite dans des conditions basiques était contrôlée par l'altération chimique météoritique en plusieurs étapes de roches ultramafiques et volcaniques et par les concentrations de Si, Al, Fe et Mg. Localement, des concentrations de S, combinées au Fe et au Ca, ont entraîné la précipitation de goethite-hématite, de gypse et de pyrite dans des cavités de dissolution en association avec la smectite dans des conditions acides d'un système perméable. [Traduit par la Rédaction], Introduction In the Turgutlu (Manisa) area of western Turkey, the Çaldag lateritic deposit has a Ni-Co reserve of approximately 38 000 000 t (M. Yildiz 1977 (unpublished), 1982 (unpublished), 1994 [...]

A technically challenging analysis has revealed the physical properties of a mineral at pressures and temperatures as high as those in Earth's mantle. The findings have implications for our understanding of Earth's deep interior.The properties of a basalt-derived mineral at high pressures., Author(s): Johannes BuchenAuthor Affiliations:High-pressure experiments cast light on deep-Earth mineralogy Beneath the oceans, Earth's crust consists mainly of a rock called basalt. When exposed to high pressures as a result [...]

The Cobequid Highlands have a long and productive history as a region with a great endowment of mineral deposits hosting many commodities (e.g., Fe, Ba, Cu, Co, Ni, and Au). [...]

Enigmatic millimetre-scale micro-concretions with pseudocrystal faces and dominated by green clay minerals occur in unfossiliferous siliciclastic mudstone of the Lower Ordovician (479.0-466.0 Ma) Tonggao Formation, South China. The fossil-free mudstone unit is associated with local biodiversity decline. The mineralogy and mineral chemistry of these concretions were unknown previously, and this study comprises a preliminary investigation. The concretions are dominated by Fe-rich phyllosilicate minerals including glauconite and clinochlore, with minor quartz and traces of magnetite. The textural relations between the micro-concretions and the surrounding matrix, and the preservation of original mudstone laminations within the concretions, point to an origin during early diagenesis. The mineralogy and chemistry of these concretions are consistent with an origin in a restricted, hypersaline, relatively deep-water environment, in accordance with stratigraphical and paleonotological data. These micro-concretions provide clues for a stressed environment with poor water circulation and anomalies of salinity and oxygen. Des micro-concretions enigmatiques d'echelle millimetrique, avec des faces pseudocristallines et dominees par des mineraux argileux verts, se trouvent dans des mudstones siliclastiques non fossiliferes de la Formation de Tonggao de l'Ordovicien inferieur (479,0-166,0 Ma), dans le sud de la Chine. L'unite mudstone sans fossile est associee a un declin de la biodiversite locale. La mineralogie et la chimie des mineraux de ces concretions n' etaient pas connues anterieurement et la presente etude comprend une investigation preliminaire. Les concretions sont dominees par des mineraux phyllosilicates riches en Fe, incluant la glauconite et le clinochlore, avec un peu de quartz et des traces de magnetite. Les relations texturales entre les micro-concretions et la matrice environnante ainsi que la preservation des laminations originales du mudstone a l'interieur des concretions signalent une origine au debut d'une diagenese. La mineralogie et la chimie de ces concretions correspondent a une origine dans un environnement aqueux limite, hypersalin et relativement profond, ce qui concorde avec les donnees stratigraphiques et paleontologiques. Ces micro-concretions fournissent des indices qu'il s'agissait d'un environnement perturbe avec une mauvaise circulation d' eau et des teneurs anormales en sel et en oxygene. [Traduit par la Redaction], Introduction The Lower Ordovician (479.0-466.0 Ma) Tonggao Formation in Guizhou, South China (Fig. 1), contains abundant microconcretions of clay minerals, which occur in the largely unfossiliferous units of siliciclastic deposits [...]

The Zonguldak terrane is a Gondwana-derived continental microplate along the Black Sea coast in northwest Anatolia. It includes a Cadomian basement, with oceanic- and island-arc sequences, unconformably overlain by siliciclastic rocks of Ordovician to Middle Silurian age. After a period of deformation and erosion, late Lower Devonian (Emsian) quartzites and shallow-marine limestones unconformably cover Middle Silurian (Wenlock) graptolitic shales. Along several cross sections across the unconformity plane, the mineralogical characteristics of the Paleozoic sedimentary rocks in the Zonguldak terrane are studied to check whether this regional unconformity is only of epeirogenic nature or the result of a thermal event. In addition to the appearance of kaolinite in Devonian units, crystal-chemical data of illites show a sudden jump at the unconformity plane. The b cell dimension values of illites of Ordovician-Silurian units are somewhat higher than those of Devonian- Carboniferous units and show a drastic drop between the Silurian and Devonian units. The new mineralogic data indicate that the pre- Emsian rocks in the Zonguldak terrane experienced a thermodynamo event, prior to the Emsian transgression. This Caledonian- time event is also reported in east Moesian terrane but not noticed in the neighboring Istanbul-Zonguldak and in the west Moesian--Balkan--Kreishte terranes. By this, it is suggested that Zonguldak and east Moesian terranes behaved independently from the Istanbul-Balkan terranes during the closure of the Rheic Ocean. They very likely docked to Laurussia during Emsian by strike-slip faults and remained thereon at its platform margin, where the Middle-Late Devonian shallow-platform conditions were followed by fluvial (lagoon and delta) conditions and deposition of coal during Late Carboniferous. Le terrane de Zonguldak est une microplaque continentale provenant de Gondwana, situe le long de la cote de la mer Noire dans le nord-ouest de l'Anatolie. Il comprend un socle cadomien avec des sequences d'arcs oceaniques et d'arcs insulaires, il est recouvert de maniere discordante par des roches silicoclastiques datant de l'Ordovicien au Silurien moyen. Apres une periode de deformation et d'erosion, des quartzites et des calcaires marins peu profonds du Devonien inferieur tardif (Emsien) recouvrent de maniere discordante des shales a graptolites du Silurien moyen (Wenlockien). Le long de plusieurs coupes transversales a travers le plan de discordance, les caracteristiques mineralogiques des roches sedimentaires du Paleozoi'que dans le terrane de Zonguldak ont ete etudiees afin de verifier si cette discordance etait de nature seulement epeirogenique ou si elle etait accompagnee d' un evenement thermique. En plus de la venue de kaolinite dans les unites du Devonien, les donnees chimiques et cristallines des illites montrent un accroissement soudain au plan de la discordance. Les valeurs de la dimension b des illites des unites de l' Ordovicien-Silurien sont quelque peu plus elevees que celles des unites du Devonien-Carbonifere et montrent une baisse importante entre les unites du Silurien et du Devonien. Les nouvelles donnees mineralogiques indiquent que dans le terrane de Zonguldak les roches pre-emsiennes ont subi un evenement thermodynamique avant la transgression a l'Emsien. Cet evenement de l'epoque caledonienne est aussi enregistre dans le terrane de Moesie Est mais il n'a pas ete remarque dans les terranes avoisinants d'Istanbul-Zonguldak et de Moesie Ouest--Balkan--Kreishte. Selon ces faits, les terranes de Zonguldak et de Moesie Est se comportaient de maniere independante des terranes Istanbul Balkan durant la fermeture de l'ocean Rheique. Ils se sont tres probablement arrimes au continent Laurussia durant l'Emsien par des failles de decrochement et sont restes a la plate-forme/bordure, ou les conditions de la plate-forme peu profonde au Devonien moyen tardif ont ete suivies de conditions fluviales (lagunes et deltas) et la deposition de charbon au Carbonifere tardif. [Traduit par la Redaction], Introduction The Istanbul-Zonguldak terrane comprising the classical (e.g., de Verneuil 1836-1837) successions of Variscan 'Paleozoic of Istanbul' is a Variscan terrane assemblage (Fig. 1) or a composite terrane (sensu Howell [...]

An experimental study has been carried out to investigate the effects of isotropic compression, wetting, and drying on the initial shear stiffness of Zenoz kaolin, an unsaturated lean clay, both in normally consolidated and overconsolidated conditions. The proposed study was conducted using fixed-free resonant column--torsional shear (RCTS). Specimens were compacted using the undercompaction technique. Initial shear stiffness was measured almost continuously along complex stress paths including (i) an initial equalization stage to a suction value of 0, 50, 150, and 300 kPa; (ii) an isotropic compression stage at constant suction, up to a net stress high enough to move the loading collapse line; (iii) an isotropic unloading stage at constant suction; (iv) a wetting and (or) drying path. The mentioned stress path allowed elimination or determination of the overconsolidation effect on the initial shear stiffness measured. The behavior observed is qualitatively similar to that of saturated soil, while wetting data clearly indicate that [G.sub.0] depends significantly on volumetric behavior. In normally consolidated samples where wetting is accompanied by collapse, reduction in suction has no remarkable effect on G0. Conversely, in overconsolidated samples [G.sub.0] reduces significantly as suction decreases. Key words: unsaturated kaolin, small-strain behavior, volumetric behavior, stress history, isotropic compression and wetting. Une etude experimentale a ete realisee pour etudier les effets de la compression isotrope, du mouillage et du sechage sur la rigidite en cisaillement initiale d'un kaolin Zenoz, une argile maigre non saturee, autant en conditions de consolidation normale et de surconsolidation. L'etude proposee a ete realisee avec une colonne de resonance-isaillement en torsion (CRCT) fixe-libre. Les echantillons ont ete compactes a l' aide de la technique de sous-compaction. La rigidite au cisaillement initiale a ete mesuree presque en continu le long de cheminements des contraintes complexes incluant : (i) une etape initiale d'egalisation a une valeur de succion de zero, 50, 150 et 300 kPa; (ii) une etape de compression isotrope a succion constante, jusqu' a une contrainte nette suffisante pour deplacer la ligne rupture en chargement; (iii) une etape de dechargement isotrope a succion constante; (iv) un cheminement de mouillage et (ou) de drainage. Le cheminement des contraintes mentionne permet d' eliminer ou de determiner l' effet de la surconsolidation sur la rigidite en cisaillement initiale mesuree. Le comportement observe est similaire qualitativement a celui d'un sol sature, tandis que les donne es de mouillage indiquent clairement que [G.sub.0] depend de facon significative du comportement volumetrique. Dans le cas d'echantillons normalement consolides pour lesquels le mouillage s'accompagne d'une rupture, la reduction de la succion n'a pas d'effet marque sur [G.sub.0].Al'inverse, dans le cas d'echantillons surconsolides, [G.sub.0] diminue significativement lorsque la succion diminue. Mots-cles : kaolin non sature, comportement a faible deformation, comportement volumetrique, historique des contraintes, compression et mouillage isotrope. [Traduit par la Redaction], Introduction The initial shear modulus, [G.sub.0], is a key parameter for predicting the dynamic response of soils, for the design and the analysis of earthquake-resistant foundations and vibrating machine foundations, [...]

To better understand the glacial history of the ice sheets surrounding Baffin Bay and to provide information on sediment pathways, samples from 82 seafloor grabs and core tops, and from seven box cores were subjected to quantitative X-ray diffraction weight percent (wt.%) analysis of the 2000 m) all show an abrupt drop in calcite wt.% (post-5 cal ka BP?) following a major peak in detrital carbonate (mainly dolomite). This dolomite-rich detrital carbonate (DC) event in JR175BC06 is possibly coeval with the Younger Dryas cold event. Four possible glacial-sourced end members were employed in a compositional unmixing algorithm to gain insight into down core changes in sediment provenance at the deep central basin. Estimates of the rates of sediment accumulation in the central basin are only in the range of 2 to 4 cm/cal ka, surprisingly low given the glaciated nature of the surrounding land. Afin de mieux comprendre l'historique glaciaire des inlandsis autour de la baie de Baffin et de fournir de l'information sur les chemins pris par les sediments, des echantillons de quatre-vingt-deux (82) prelevements de fond oceanique au hasard et de sommets de carottes et de sept (7) carottiers a boite ont ete soumis a des analyses de rayons-X quantitatives de pourcentage poids sur la fraction des sediments inferieure a 2 mm. Les echantillons ont ete preleves entre les latitudes 67 et 78°N a des profondeurs entre 155 et 2375 m et ils ont ete recuperes lors de croisieres entre 1964 et 2009. Des donnees sur la granulometrie, les caracteristiques magnetiques et la reflexion de la couleur ont aussi ete obtenues sur plusieurs echantillons. Vingt et une (21) especes minerales non argileuses et dix especes minerales argileuses ont ete identifiees; le pourcentage poids moyen des mineraux non argileux etait de 70 % et ils etaient composes surtout de quartz, de divers feldspaths et de dolomite alors que les mineraux argileux dominants etaient 1M illite, biotite et chlorite. Une analyse par grappes des cotes des principales composantes a permis d'identifier trois principaux groupes mineraux, lesquels etaient aussi fortement associes aux proprietes granulometriques et magnetiques des sediments. Les sediments preleves par des carottiers a boite dans le bassin central profond (>2000 m) montraient tous une chute abrupte du pourcentage poids de la calcite (plus recent que 5 ka cal. avant le present?) apres une crete significative de carbonate detritique (surtout de la dolomite). Cet evenement de carbone detritique riche en dolomite dans l'echantillon JR175BC06 est peut-etre contemporain de la periode froide du Dryas recent. Quatre membres terminaux possiblement de source glaciaire ont ete utilises dans un algorithme de demelage compositionnel dans le but de mieux comprendre les changements de source des sediments en profondeur dans les carottes provenant du bassin central profond. Des estimations des taux d'accumulation de sediments dans le bassin central ne sont que de l'ordre de 2 a 4 cm/ka cal., etonnamment faible etant donne la nature glaciee du terrain environnant. [Traduit par la Redactionl, Introduction Baffin Bay is, and certainly was, one of the most heavily impacted ocean basins during the late Cenozoic glaciations (Aksu 1981; Hiscott et al. 1989; Srivastava et al. 1989). [...]

Planetary mineralogy can be revealed through a variety of remote sensing and in situ investigations that precede any plans for eventual sample return. We briefly review those techniques and focus on the capabilities for on-surface in situ examination of Mars, Venus, the Moon, asteroids, and other bodies. Over the past decade, Raman spectroscopy has continued to develop as a prime candidate for the next generation of in situ planetary instruments, as it provides definitive structural and compositional information of minerals in their natural geological context. Traditional continuous-wave Raman spectroscopy using a green laser suffers from fluorescence interference, which can be large (sometimes saturating the detector), particularly in altered minerals, which are of the greatest geophysical interest. Taking advantage of the fact that fluorescence occurs at a later time than the instantaneous Raman signal, we have developed a time-resolved Raman spectrometer that uses a streak camera and pulsed miniature microchip laser to provide picosecond time resolution. Our ability to observe the complete time evolution of Raman and fluorescence spectra in minerals makes this technique ideal for exploration of diverse planetary environments, some of which are expected to contain strong, if not overwhelming, fluorescence signatures. We discuss performance capability and present time-resolved pulsed Raman spectra collected from several highly fluorescent and Mars-relevant minerals. In particular, we have found that conventional Raman spectra from fine grained clays, sulfates, and phosphates exhibited large fluorescent signatures, but high quality spectra could be obtained using our time-resolved approach. OCIS codes: 300.6500, 300.6450, 300.6280, 300.6190.

The prior two papers in this series reported on the geoenvironmental and geomechanical properties of 20 stabilized dredged material (SDM) blends using dredged material (DM) from the U.S. Army Corps of Engineers Craney Island confined disposal facility. The pozzolans included lime, cement kiln dust (CKD), class F fly ash, and two cements (portland and slag cement). This paper reports on the mineralogical evolution of the SDM blends over a 6-month curing period using techniques new to mainstream geotechnical engineering: X-ray diffraction (XRD) with Rietveld quantification analysis which allows direct quantitative mineralogical comparisons between soil samples. Despite being classified as a high plasticity clay-organic clay (CH/OH soil), XRD showed that the DM contained no montmorillonite, illite or kaolinite, and was thus mineralogically unreactive. The quartz, feldspar, and mica contents were numerically tracked and were shown to remain stable 6 months after blending. The chlorite (in DM) content decreased over time and with the fly ash served as the sources of soluble silica and alumina for pozzolanic reactions especially in the lime-based SDM blends. Lime in the lime-based blends persisted in significant quantities (3%) as unreacted portlandite [Ca[(OH).sub.2]] even at 6 months curing, indicating that the solubility of silica in the DM was the limiting factor for strength development. New (ettringite and hydrocalumite) mineral formation was quantified. CKD provided high early strength (7 and 28 days) when used in combination with small amounts of lime that provided prolonged pH buffering; CKD alone or in combination with fly ash did not maintain elevated pH (>10.8) over 6 months. Overall, the unconfined compressive strength, pH, and mineralogy results at 6 months were substantially different compared to the standard curing time of 28 days, confirming similar findings of previous long-term stabilization-solidification studies. DOI: 10.1061/(ASCE)GT.1943-5606.0000292 CE Database subject headings: Mineralogy; Soil stabilization; Soil cement; Dredging; Recycling; Laboratory tests; Mechanical properties. Author keywords: Mineralogy; Soil stabilization; Soil cement; Dredge spoil; Byproduct utilization; Laboratory tests.

The geoenvironmental characterization of COPR at two deposition sites (New Jersey and Maryland) included geotechnical, chemical, mineralogical, and leaching analyses of three main chromite ore processing residue (COPR) types [gray-black (GB), hard brown (HB), clayey (C)]. Quantitative mineralogical analyses were instrumental in the delineation of the geochemical differences between the three COPR types, which enabled a framework to predict COPR response to potential remediation schemes. Overall, COPR mineralogy resembled cement, with hydration and pozzolanic reactions dominating its geochemistry. GB COPR was largely unreacted despite its prolonged exposure to humid conditions, while HB COPR was completely hydrated and contained high Cr(VI) concentrations. The two materials were chemically similar, with dilution accounting for the chemical and density differences. While the total acid neutralization capacity (ANC) of GB and HB was the same, the ANC at high pH (8-12) was higher in HB due to the dominance of hydrating materials, leading to more buffering capacity and lower Cr(VI) leaching levels. It is concluded that GB and HB were derived from the same ore and process and that postdepositional transformations account for the emergence of HB layers in COPR sites. The physicochemical properties of HB [hardness, high and inaccessible Cr(VI), high ANC] are complicating factors for in situ COPR reductive treatment in the presence of HB. DOI: 10.1061/(ASCE)GT.1943-5606.0000233 CE Database subject headings: Chromium; Mineralogy; Site investigation; Expansive soils; Hazardous wastes. Author keywords: Chromium; Mineralogy; Site investigation; Expansive soils; Hazardous wastes.

A quantitative compilation of carbonate skeletal mineralogy through the Phanerozoic shows a progressive replacement of low-Mg calcite by aragonite. This general trend overrides the subsidiary trend of greenhouse intervals favoring biogenic low-Mg calcite mineralogies (calcite seas), and icehouse intervals facilitating aragonite + high-Mg calcite mineralogies (aragonite seas). The replacement of low-Mg calcite by aragonite was, however, achieved episodically at mass extinction intervals. In particular, the end-Permian extinction both preferentially removed species bearing 'unfavorable' low-Mg calcite, and allowed the selective radiation of biota with 'favorable' aragonite. This demonstrates the importance of incumbency in the evolution of skeletal mineralogy. We suggest that the broad increase of aragonitic biota has been controlled by changes in atmospheric carbon dioxide partial pressure (pC[O.sub.2]) via carbonate mineral kinetics. Through the Phanerozoic, broadly decreasing pC[O.sub.2] levels led to decreasing total alkalinity and dissolved inorganic carbon, and increasing oceanic pH. Superimposed upon this general trend, there are cyclic episodes of relatively high pC[O.sub.2] and saturation state combined with a lower ratio of magnesium to calcium ions in seawater driven by the relatively slow changes in mid-ocean ridge expansion rates. Mass extinction events, many of which may have been caused by rapid global changes in temperature and/or pC[O.sub.2], represent major intervals of turnover. doi: 10.1130/G30204A.1

Pristine meteoritic materials carry light element isotopic fractionations that constrain physiochemical conditions during solar system formation. Here we report the discovery of a unique xenolith in the metal-rich chondrite Isheyevo. Its fine-grained, highly pristine mineralogy has similarity with interplanetary dust particles (IDPs), but the volume of the xenolith is more than 30,000 times that of a typical IDP. Furthermore, an extreme continuum of N isotopic variation is present in this xenolith: from very light N isotopic composition [[delta].sup.15][N.sub.AIR] = -310 [+ or -] 20 [per thousand]), similar to that inferred for the solar nebula, to the heaviest ratios measured in any solar system material ([[delta].sup.15][N.sub.AIR] = 4,900 [+ or -] 300 [per thousand]). At the same time, its hydrogen and carbon isotopic compositions exhibit very little variation. This object poses serious challenges for existing models for the origin of light element isotopic anomalies. isotopic fractionation | pristine meteorites | Solar System

This study evaluated the effects of physical characteristics and geologic factors on the shear strength of compacted sands from Wisconsin that are used as granular backfill for mechanically stabilized earth walls and reinforced soil slopes. Physical properties and shear strength were determined for 30 compacted sands collected from a broad range of geological deposits. Relationships between strength/deformation behavior, geologic origin, and physical properties were used to categorize the sands into four friction angle groups. Sands with the lowest friction angle are derived from weathering of underlying sandstones, and tend to be medium-fine, well-rounded, and poorly graded sands. Sands with the highest friction angle are from recent glacial activity and tend to be coarser grained, well-graded, and/or angular sands. A multivariate regression model was developed that can be used to predict friction angle ([PHI]') of compacted sands from comparable geological origins based on effective particle size ([D.sub.10]), maximum dry unit weight ([[gamma].sub.dmax]), and Krumbein roundness ([R.sub.s]). CE Database subject headings: Sand; Friction; Displacement; Mineralogy; Backfills; Slopes.

Visible, near-infrared, thermal, and Mossbauer spectroscopic data from the exposed, bright track soil at the 'Paso Robles' site within Gusev crater, Mars, indicate the presence of [Fe.sup.3+]-sulfates and possibly [Fe.sup.3+]-phosphates admixed with the host soil. When the spectroscopic analyses are combined with constraints imposed by chemical data, the determined dominant [Fe.sup.3+]-sulfate component is hydrous, and all of the spectroscopic methods suggest that it is probably ferricopiapite or some closely related, structurally similar species, possibly mixed with other [Fe.sup.3+] sulfates such as butlerite or parabutlerite, or perhaps (para)coquimbite, fibroferrite, or metahohmanite. Such an assemblage is consistent with formation in a highly oxidized, relatively dehydrated environment with the bulk-sulfate assemblage having OH/(OH + 2S[O.sub.4]) of < ~0.4. Some [Fe.sup.3+] is likely to be associated with phosphates in the soil in the form of ferristrunzite or strengite. Keywords: Mars, spectroscopy, sulfate, phosphate, mineralogy, spectra, Paso Robles, acid

In the present study, experiments in non-saturated leaching columns were conducted to characterize the neoformed phases that precipitate at the interface between two waste residues having different chemical characteristics: an acid mine drainage producer residue (i.e., pyritic sludge) and an acidity neutralizer residue (i.e., coal combustion fly ash). A heating source was placed on top of one of the columns to accelerate oxidation and precipitation of newly formed phases, and thus, to observe longer-scale processes. When both residues are deposited together, the resulting leachates are characterized by alkaline pH, and low sulfate and metal concentrations. Two mechanisms help to improve the quality of the leachates. Over short-time scales, the leaching of pyrite at high pH (as a consequence of fly ash addition) favors the precipitation of ferrihydrite, encapsulating the pyrite grains and attenuating the oxidation process. Over longer time scales, a hardpan is promoted at the interface between both residues due to the precipitation of ferrihydrite, jarosite, and a Ca phase--gypsum or aragonite, depending on carbonate ion activity. Geochemical modeling of leachates using PHREEQC software predicted supersaturation in the observed minerals. The development of a relatively rigid crust at the interface favors the isolation of the mining waste from weathering processes, helped by the cementation of fly ash owing to aragonite precipitation, which ensures total isolation and neutralization of the mine residues. Keywords: Acid mine drainage, fly ash, mine residue, microencapsulation, hardpan formation

ASTM C 33 limits the amount of aggregate smaller than 75 [micro]m (No. 200 sieve) to be used in concrete. There is considerable interest in altering ASTM C 33 to allow a higher percentage of these microfine aggregates, particularly in the case of manufactured aggregates. However, before this can be done, the positive and negative effects of microfine aggregates on concrete performance must be fully investigated. Previous research has indicated that there is not a strong correlation between standard aggregate characterization tests and concrete performance when microfines are present. In this study, several methods of characterizing microfine aggregates were investigated. The intent was to identify the characteristics of microfines that govern their effects on concrete performance. A second goal was to identify easy-to-use test methods that could be used to simply and inexpensively identify good and poor performing microfine aggregates. Three easy-to-use tests were identified that correlated well with concrete performance: the methylene blue test, a particle packing assessment by the weight of microfine aggregates adhering to a single drop of water, and the loose packing tests described in ASTM C 1252. DOI: 10.1061/(ASCE)0899-1561(2007)19:11(957) CE Database subject headings: Concrete aggregates; Concrete tests; Particle size; Mineralogy.

The usefulness of cathodoluminescence (CL) in mineralogy and petrology is largely due to its high sensitivity to variations in the chemical compositions of minerals. Difficulty in interpretation of CL images, however, often limits their use beyond the identification of growth zones, which are then analyzed using other, more readily quantifiable, techniques. The use of scanning electron microscopy (SEM) CL in hyperspectral imaging mode, combined with simultaneously acquired X-ray composition mapping, extends the technique by allowing the separation of spectral features and their correlation with elemental composition. In this paper, we describe the use of such measurements in conjunction with multivariate statistical analysis to automatically identify and characterize zones in calcite and zircon. We demonstrate that this novel combination of techniques significantly increases the effectiveness of CL as a diagnostic tool for Earth science applications. Keywords: Cathodoluminescence, hyperspectral, principal components, calcite, zircon, X-ray microanalysis

Palaeoproterozoic (ca 2,480 Ma) felsic magmatism of Malanjkhand region of central Indian Precambrian shield, referred to as Malanjkhand granitoids (MG), contain xenoliths of country rocks and mesocratic to melanocratic, fine-grained porphyritic microgranular enclaves (ME). The shape of ME is spheroidal, ellipsoidal, discoidal, elongated, and lenticular, varying in size from a few centimeters to about 2 m across. The contact of ME with the host MG is commonly sharp, crenulate, and occasionally diffuse, which we attribute to the undercooling and disaggregation of ME globules within the cooler host MG. The ME as well as MG show hypidiomorphic texture with common mineral Hbl-Bt-Kfs-Pl-Qtz assemblage, but differ in modal proportions. The variation in minerals' composition, presence of apatite needles, elongated biotites, resorbed plagiclase, ocellar quartz, and other mafic-felsic xenocrysts strongly oppose the restite and cognate origins of ME. Compositions of plagioclases ([An.sub.3]-[An.sub.29]), amphiboles (Mg/Mg+[Fe.sup.2+]=0.55-0.69), and biotites (Mg/Mg+[Fe.sup.2+]=0.46-0.60) of ME are slightly distinct or similar to those of MG, which suggest partial to complete equilibration during mafic-felsic magma interactions. Al-in-amphibole estimates the MG pluton emplacement at ca 3.4 [+ or -] 0.5 kbar, and therefore, magma mixing and mingling must have occurred at or below this level. The Fe [??] Mg substitution in biotites of ME and MG largely suggests subduction-related, calc-alkaline metaluminous (I-type) nature of felsic melts. Most major and trace elements against Si[O.sub.2] produce near linear variation trends for ME and MG, probably generated by the mixing of mafic and felsic magmas in various proportions. Trace including rare earth elements patterns of ME-MG pairs, however, show partial to complete equilibration, most likely governed by different degrees of elemental diffusion. The available evidence supports the model of ME origin that coeval mafic (enclave) and felsic (MG) magmas produced a hybrid (ME) magma layer, which injected into cooler, partly crystalline MG, and dispersed, mingled, and undercooled as ME globules in a convectively dynamic magma chamber.

The mineralogy of a planetary surface is a diagnostic product of its formation and geologic evolution. Global assessment of lunar mineralogy at high spatial resolution has been a long standing goal of lunar exploration. Currently, the only global data available for such study is multispectral imagery from the Clementine mission. We use the detailed compositional, petrographic, and spectroscopic data of lunar soils produced by the Lunar Soil Characterization Consortium to explore the use of multispectral imaging as a diagnostic tool. We compare several statistically optimized formulations of links between spectral and mineral parameters and apply them to Clementine UV-VIS data. The most reliable results are for estimations of pyroxene abundance and maturity parameters (agglutinate abundance, [l.sub.s]/FeO). Estimations of different pyroxene composition (low-Ca versus high-Ca) appear good in a relative sense, but absolute values are limited by residual wavelength dependent Clementine photometric calibrations. Since the signal-to-noise of Clementine multispectral data is good at the 1-km scale, almost any combination of parameters that capture inherent spectral variance can provide spatially coherent maps, although the parameters may not actually be directly related to composition. Clementine estimates are useful for identifying scientific or exploration targets for imaging spectrometer sensors of the next generation that are specifically designed to characterize mineralogy. Keywords: Moon, surface; Spectroscopy; Mineralogy

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2006.02.018 Byline: Kathleen C. Benison (a), Brenda Beitler Bowen (a)(b) Keywords: Mars; surface; Geological processes; Mineralogy; Exobiology; Earth Abstract: Acid saline lake systems in Western Australia may be the best known modern terrestrial analog for the Burns formation on Mars and, thus, provide information about past environments and life on Mars. Author Affiliation: (a) Department of Geology, Central Michigan University, 314 Brooks Hall, Mt. Pleasant, MI 48859, USA (b) Department of Earth and Atmospheric Sciences, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47907, USA Article History: Received 20 December 2005; Revised 21 February 2006

Piergorite-(Ce) is a new mineral found at Tre Croci, Vetralla, Italy with simplified formula [Ca.sub.8][Ce.sub.2][([Al.sub.0.5] [Fe.sup.3+.sub.0.5]).sub.[sigma]1][([??],Li,Be).sub.2][Si.sub.6] [B.sub.8][O.sub.36][(OH,F).sub.2]. It occurs as strong intergrowths of small crystals, colorless to pale yellow, associated with sanidine, mica, magnetite, ruffle, titanite, and other Th-U-REE bearing minerals, in miarolitic cavities of a syenitic ejectum. Piergorite-(Ce) is biaxial negative, [n.sub.[alpha]] = 1.717 (1), [n.sub.[beta]] = 1.728 (1), and [n.sub.[gamma]] = 1.735 (1), 2[V.sub.meas] = 68(2)[degrees], X = b, and Z ^ c = 7(1)[degrees]. Crystals show tabular habit and a very good {010} cleavage; twinning along the (30[??]) plane produces 'L' forms. The three strongest lines in the simulated powder diffraction pattern ([d.sub.obs], I, hkl) are: 2.65 [Angstrom], 100.0, (213,[??]13); 1.91 [Angstrom], 48.3, (223,[??]23, 821); 2.90 [Angstorm], 44.9, ([??]03,[??]12). The structure was solved by Patterson synthesis from X-ray diffraction data [monoclinic, space group P2/a, a = 28.097(3) [Angstorm], b = 4.777(1) [Angstorm], c = 10.236(2) [Angstorm], [beta] = 96.81(1)[degrees], V= 1364.2(7) [[Angstorm].sup.3], Z = 2] and was refined to a final [R.sub.obs] = 0.059 for 6480 Fo with Io > 3[sigma]([I.sub.o]). The structure shows similarities with the hellandite group because Si and B tetrahedra form chains along c. Hellandite structure is characterized by a single chain of five-membered rings, whereas piergorite-(Ce) shows a double chain of five-membered rings interconnected by a single octahedral site to form a three-dimensional framework containing five independent eightfold-coordinated M sites and a partly occupied T-cavity. Keywords: New mineral, piergorite-(Ce), borosilicate, crystal structure, SIMS, hellandite

Alunite and jarosite from Goldfield, Nevada, show spectacular relationships between early alunite and later jarosite. In some cases, jarosite overgrows alunite with the same crystallographic orientation and sharp contacts. Electron microprobe analyses of these phases show that they fall in the alunite-jarosite quadrilateral defined by alunite, K[Al.sub.3][(S[O.sub.4]).sub.2] [(OH).sub.6]; natroalunite, Na[Al.sub.3][(S[O.sub.4]).sub.2][(OH).sub.6]; jarosite, K[Fe.sup.3+.sub.3][(S[O.sub.4]).sub.2][(OH).sub.6]; and natrojarosite, Na[Fe.sup.3+.sub.3][(S[O.sub.4]).sub.2][(OH).sub.6]. A large compositional gap occurs between alunite-natroalunite and jarosite-natrojarosite. This gap has no crystal chemical basis because Al and [Fe.sup.3+] can readily substitute for each other in octahedral site coordination. We believe the 'on-off switch' behavior between early alunite and later jarosite is caused by an oxidant entering the system, oxidizing [Fe.sup.2+] in solution to [Fe.sup.3+], raising the Eh and possibly oxidizing [H.sub.2]S to lower the pH, and thus stabilizing jarosite relative to alunite. The activity of Fe (as [Fe.sub.2+]) increased in the solution because of prolonged alunite crystallization but could not readily enter the crystal structure until it was oxidized to [Fe.sup.3+]. The jarosite overgrowths show striking oscillatory zoning of Na- and K-rich bands. This reflects up to an order of magnitude change in the fluid K/Na ratio. These textures are interpreted to represent rapid growth and kinetic control of delivery of free Na and K to the crystal-fluid interface. This could be due to some combination of Na and K diffusion rates in the solution and complex ion breakdown involving Na and K. Keywords: Jarosite, Mars, electron microprobe, terrestrial analogs

We have modeled the vibrational spectrum of brucite, the common phase of magnesium hydroxide, at 1 bar ([10.sup.5] Pa) by two separate techniques: molecular dynamics simulation and vibrational mode analysis. Molecular dynamics simulation of a model supercell provides information (from the power spectrum of the atomic velocity autocorrelation function) about the frequencies and directions of atomic thermal motions, using a defined energy force field. Vibrational mode analysis gives complementary information about the frequencies, nature, and infrared and Raman activity of the computed modes of the same system. Using both methods we find (in addition to the spectroscopically active modes) inactive modes up to around 1000 [cm.sup.-1], corresponding to MOH bending (OH rotational) motions. We invoke these modes to explain the published inelastic neutron scattering data, and suggest that their relatively high frequency is an inevitable consequence of repulsive interactions between neighboring H atoms. Keywords: Brucite, magnesium hydroxide, infrared, molecular dynamics, neutron scattering, vibrational spectra

The OH-structural characteristics of an iron-rich palygorskite from Western Macedonia, Greece (Gr-1) and an aluminous palygorskite from Florida (PF1-1) were examined by combined Fourier-transform near-infrared reflectance (NIR) and mid-infrared attenuated total reflectance (ATR) spectroscopy. Analyses of samples heated from ambient to 130 [degrees]C allowed for the development of a self-consistent set of band assignments for the structural and surface OH and [H.sub.2]O species of both the hydrated and dehydrated forms. The inner octahedral sites of both samples are largely accounted for by dioctahedral AlAlOH, Al[Fe.sup.3+]OH, and [Fe.sup.3+][Fe.sup.3+]OH pairs. Band intensities for these pairs are consistent with variations in the concentration of octahedral Fe and Al in the two samples. In addition, both samples display a trace trioctahedral signature in NIR, which may be related to local trioctahedral domains, or the presence of sepiolite in trace amounts, or as intergrowths. A surface [H.sub.2]O species typical of the hydrated phase was identified via its NIR combination mode at 5317 [cm.sup.-1]. The desorption of this species by heating revealed distinct silanol groups with overtone and combination modes at 7255 and 4575 [cm.sup.-1], respectively. Mg-coordinated and zeolitic [H.sub.2]O species are strongly coupled in the hydrated phase and give rise to NIR combination modes at 5190 and 5240 [cm.sup.-1]. The removal of zeolitic [H.sub.2]O causes the blue shift of the three dioctahedral OH overtones by ca. 20 [cm.sup.-1] and the rearrangement of the coordinated [H.sub.2]O manifested by the growth of sharp combination modes at ca. 5215 and 5120 [cm.sup.-1]. Keywords: IR spectroscopy, palygorskite, NIR spectroscopy, Fe-rich, hormite, hydration

Hydrogen incorporation into orthoenstatite (Pbca), low-clinoenstatite (P[2.sub.1]/c), and high-pressure clinoenstatite (C2/c) has been investigated using polarized and unpolarized infrared spectroscopy. Using shifts in OH stretching frequencies between the spectra and data from different crystal models, we test various models for hydrogen incorporation. The only significant differences between orthoenstatite and low-clinoenstatite spectra relate to anisotropy of the higher wavenumber bands, which implies a change in orientation of longer OH dipoles between the two structures. High-pressure clinoenstatite reverts to low-clinoestatite during depressurization, but subtle differences are noted between IR spectra of samples synthesized in the high-pressure clinoenstatite and low-clinoenstatite stability fields. Differences probably relate to the splitting of oxygen sites into two sets of non-equivalent sites during transformation of high-pressure clinoenstatite. The most realistic models for hydrogen incorporation into all three polymorphs involve association of hydrogen with the underbonded O2a and O2b sites. However, changes in OH dipole orientation between the different polymorphs and the effects of phase transitions on water solubility in the system MgSi[O.sub.3] mean the effects and implications of hydrogen incorporation into the three polymorphs may differ considerably. Keywords: Enstatite, transition, hydrogen, water, mantle

The reaction 2 talc + 2 forsterite = 5 enstatite + 2 [H.sub.2]O has been investigated between 1 and 3.5 GPa. Here, we report the results from 2 sets of experiments: (1) 'conventional' static quenching experiments performed several years ago in non-end-loaded and end-loaded piston-cylinder apparatus, and (2) a new set of experiments conducted in a novel type of apparatus, a 'rocking' piston cylinder. This new technique was employed for the reinvestigation to overcome segregation problems encountered during static experiments. The run-products of the latter experiments are homogenous throughout the entire capsule. The reaction was bracketed to 680-690 [degrees]C at 1 GPa, to 660-680 [degrees]C at 1.7 GPa, to 650-660 [degrees]C at 2.5 GPa, to 600-640 [degrees]C at 3 GPa, and to 550-600 [degrees]C at 3.5 GPa. The location of the reaction in P-T-space is consistent with low-pressure experimental data of Chernosky et al. (1985), and is in reasonable agreement with the 'conventional' high-pressure experiments of this study. The new experimental results were used to refine the existing thermodynamic properties of talc within the framework of the Holland and Powell (1998) database. The standard state enthalpy and entropy amount to [H.sup.o.sub.f298] = 5912.358 kJ/mol and [S.sup.o.sub.298] = 239.1 J/(K x mol). The refined standard entropy is about 9% lower than the entropy obtained calorimetrically. When the clinoenstatite-orthoenstatite transition is taken into account, [S.sup.o.sub.298] of talc improves by ~6 J/K. We assume that a further increase of the standard state entropy of talc can be achieved by varying the activity of [H.sub.2]O in the fluid as a function of pressure and temperature. Keywords: MgO-Si[O.sub.2]-[H.sub.2]O system, experimental petrology, high pressures, uncertainties, thermodynamics, database, entropy, enthalpy

A native gold bleb found in an olivine phenocryst in a picrite lava from the Emeishan Large Igneous Province (ELIP) may be the first documented case of the transport of gold as a distinct precious metal phase in a mantle-derived magma. Four picrite layers have been recognized in the lower part of the volcanic succession in the Lijiang area, in the western part of the ELIE The native gold bleb was found enclosed in an olivine phenocryst in the second picritic layer of a basalt-picrite succession in the ELIP. The gold bleb is spheroidal, about 30 [micro]m in diameter, consists of pure gold, and does not contain any other elements. In addition, native copper grains were also discovered in the serpentinized olivine phenocrysts, and native zinc and moissanite (SiC) were separated from an ~20 kg sample of picrite. The paragenesis of these minerals suggests that the primary magmas were S-unsaturated. The native gold and native copper grains are considered to be xenocrysts from the mantle, transported to shallow depths by a rising plume, and then captured by the picritic melts. The discovery of native gold and native copper grains provides direct evidence that the gold in the hydrothermal gold deposits and the native copper deposits in the ELIP lavas ultimately may be derived from a mantle plume. Keywords: Native gold, native copper, moissanite, mantle plume, olivine phenocryst, picrite, Emeishan large igneous province

The X-ray absorption angle-dependent behavior at the potassium K-edge has been determined for two end-members and two intermediate trioctahedral micas, which are representative of the [Fe.sup.2+] [Mg.sub.-1], [Fe.sup.3+][Al.sub.-1], Si[Al.sub.-1]Fe[Li.sub.-1], and [F.sub.-1]OH exchange vectors, using horizontally polarized synchrotron radiation. Experimental spectra are interpreted by the multiple scattering theory following decomposition according to the angular dependence approach of Brouder (1990). The experimental spectra sum up anisotropic effects deriving from in-plane and out-of-plane photoelectron interactions with the potassium near- and next-near neighbors up to the fifth/sixth coordination sphere. For the first time, the absorption edge of a low Z atom is decomposed so as to produce two partial patterns giving, respectively, the full in-plane absorption spectrum ([[sigma].sub.[parallel]]) and the full out-of-plane spectrum ([[sigma].sub.[perpendicular to]]). They fully describe the complete X-ray absorption dichroic behavior of layered compounds, of which mica is a prototype. [[sigma].sub.[parallel]], essentially reflects the arrangement of the atoms located in the mica interlayer space and facing tetrahedral sheets. Differences among the four micas depend on structural changes induced by the adaptation of their tetrahedral sheets to the increasing sizes of their octahedral sheet due to chemical substitutions (i.e., the [Fe.sup.2+][Mg.sub.-1] vector, mainly) and to chemical changes at the octahedral anion site ([F.sub.-1]OH vector). By contrast, [[sigma].sub.[perpendicular to]] reflects multiple-scattering interactions entering deep into the mica structure, beyond the tetrahedral sheet and well into the octahedral sheet. Such contributions reflect both changes in the anions coordinating the octahedral cations and increasing total amount of heavy atoms (essentially Fe), and differ based on electronic properties such as oxidation states (e.g., [Fe.sup.2+] and [Fe.sup.3+]). Therefore, angle-dependent XANES spectroscopy is one of the rare spectroscopic techniques able not only to detect, but also to quantify structural effects in the atoms at the medium-to long-range order. Keywords: Mica, XAS, polarized XANES, potassium K-edge, trioctahedral micas, crystal structure

A cordierite sample (42/IA) from Kiranur, South India, and an ilvaite sample (ISX1) from Serifos, Greece, have been characterized and prepared for use as potential electron microprobe reference samples. By combining different high-precision analytical methods, we determined the major-, minor-, and trace-element composition of these samples and demonstrated their near-stoichiometric composition and high homogeneity at the micrometer level. The chemical composition (working values) of ilvaite ISXI is (in wt%): Si[O.sub.2] = 29.68%; [Al.sub.2][O.sub.3] = 0.67%; [Fe.sub.2][O.sub.3] = 34.72%; FeO = 18.67%; Fe[O.sub.T] = 51.52 %; MnO = 0.31%; MgO = 0.22%; CaO = 13.76%; [H.sub.2]O = 2.21%; and of cordierite 42/IA is (in wt%): Si[O.sub.2] = 49.65; [Al.sub.2][O.sub.3] = 33.17%; Fe[O.sub.T] = 2.34%; MnO = 0.03%; MgO = 12.44%; [Na.sub.2]O = 0.33%; [H.sub.2]O = 1.21%; C[O.sub.2] = 0.59%. Aliquots of these samples for use as primary or secondary electron microprobe reference sample can be obtained on request. Keywords: Cordierite, ilvaite, EMPA, LA-ICP-MS, ICP-OES, microprobe reference sample

The free energy of formation of zircon (ZrSi[O.sub.4]) from its oxides was determined between 1100 and 1300 K by an electrochemical method, in which values of [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] defined by the two assemblages [Fe.sub.2]Si[O.sub.4]-Fe-Si[O.sub.2] (fayalite-iron-quartz) and [Fe.sub.2] Si[O.sub.4]-Fe-Zr[O.sub.4]-ZrSi[O.sub.4] were each measured using oxygen concentration cells with calcia-stabilized zirconia solid electrolytes. The difference in [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] between these two assemblages corresponds to the reaction Zr[O.sub.2] + Si[O.sub.2](qz) = ZrSi[O.sub.4]. The results, when analyzed using calorimetric data for the entropies and high-temperature heat capacities of ZrSi[O.sub.4], Zr[O.sub.2], and Si[O.sub.2](quartz), yields [[DELTA].sub.f,ox][H.sup.0.sub.298K] = -24.0 [+ or -] 0.2 kJ/mol for ZrSi[O.sub.4], in good agreement with the calorimetric value of Ellison and Navrotsky (1992). ZrSi[O.sub.4] is predicted to decompose to Zr[O.sub.2] plus Si[O.sub.2] (cristobalite) at 1938 K, assuming a temperature of 1430 K for the martensitic phase transition between the tetragonal and monoclinic forms of Zr[O.sub.2] (baddeleyite), with an enthalpy of transition of 8.67 kJ/mol. The same experimental approach was used also to determine the free energy of formation of hafnon (HfSi[O.sub.4]). The entropy of hafnon ([S.sup.0.sub.298K] = 93.6 J/mol x K) is similar to that for zircon, but the enthalpy of formation is slightly more exothermic ([[DELTA].sub.f.ox]/[H.sup.0.sub.298K] = -25.0 [+ or -] 0.2 kJ/mol). The cells with either ZrSi[O.sub.4] + Zr[O.sub.2] or HfSi[O.sub.4] + Hf[O.sub.2] produce an anomalous excursion in EMF when the temperature of the [alpha]-[gamma] transition in Fe metal at 1184 K is traversed; this excursion takes >12 hours to decay back to the equilibrium value. This behavior is presumably related to strain caused by the volume change of the [alpha]-[gamma] transition. The redetermination of the [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] of the [Fe.sub.2] Si[O.sub.4]-Fe-Si[O.sub.2](qz) equilibrium (the quartz-fayalite-iron or QFI oxygen buffer) carried out in the course of this study gave results in reasonable agreement with previous work, but with a different slope vs. temperature, implying a slightly higher value of [S.sup.0.sub.298K] for [Fe.sub.2]Si[O.sub.4] than the currently accepted calorimetric datum (i.e., 153.5 vs. 151.0 [+ or -] 0.2 J/K x mol). Keywords: Zircon, hafnon, free energy of formation, fayalite, thermodynamic data

Mossbauer spectroscopy, [H.sub.2]O, and microprobe analysis techniques have been used to study upper mantle fcrrikaersutite megacrysts from the scoria cones of the Ash Sham alkaline volcanic field, northeastern part of the Arabian plate. Mossbauer spectra, collected at 298 K, indicate that the kaersutites are highly oxidized and all iron occurs as [Fe.sup.3+]. Two components were detected within the [Fe.sup.3+] quadrupole splitting distribution of the C-type sites and were assigned to M1 and M2-3 sites. The quadrupole splitting (QS) varies between 0.734-0.87 mm/s ([Fe.sup.3+] M1) and 1.28-1.45 mm/s ([Fe.sup.3+] M-23). The kaersutite has a large oxy component in the amphibole OH-site (1.49-1.85 [O.sup.2-] apfu) similar to the mantle-derived kaersutites. The very high ferric concentration in the kaersutites would suggest crystallization from a relatively oxidizing magma, perhaps with [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] close to the fayalite-magnetite-quartz (FMQ), and may be a function of the high [Fe.sup.3+]/[Fe.sub.tot], of the metasomatic fluid that crystallized these amphiboles. Keywords: Mossbauer, microprobe, ferrikaersutite, upper mantle, Arabian plate, oxidation, metasomatism

The structural behavior of a cancrinite, [Na.sub.5.96][Ca.sub.1.52] [[Al.sub.6][Si.sub.6][O.sub.24]][(C[O.sub.3]).sub.1.57] x 1.75[H.sub.2]O, was determined by using in situ synchrotron X-ray powder diffraction data [[lambda] = 0.91806(5) [Angstrom]] at room pressure and from 25 to 982 [degrees]C. The sample was heated at a rate of about 9.5 [degrees]C/min, and X-ray traces were collected at about 15 [degrees]C intervals. The satellite reflections in cancrinite were lost at about 504 [degrees]C, where a phase transition occurs. All the unit-cell parameters for cancrinite also show a discontinuity at 504 [degrees]C. Initially, the [Ca x C[O.sub.3]] clusters and their vacancies are ordered in the channels, and this ordering is destroyed on heating to give rise to the phase transition. Cancrinite loses water continuously until about 625 [degrees]C; thereafter an anhydrous cancrinite phase exists. From 25 to 952 [degrees]C, a minimal amount of C[O.sub.2] is lost from the structure. Over this temperature range, the average bridging angle, which is an indication of the degree of rotation of the tetrahedra, increases from 143.7(4) to 147.7(5)[degrees]. Rotations of the tetrahedra are caused by expansion of the Nal-O2 bond lengths. Keywords: Cancrinite, high-temperature structure, phase transitions, dehydration, Rietveld refinements, synchrotron radiation

An experimental study on smectite dissolution was carried out using in-situ TMAFM and CMAFM (tapping mode and contact mode atomic force microscopy, respectively) analyses at 25 [degrees]C under alkaline conditions. Smectite particles dissolved via the retreat of the edge surfaces without scratching by the AFM tip, except in a series of the dissolution experiment in CMAFM. The retreat of each straightened edge surface appeared to occur with a constant rate. In contrast, the basal surface was unreactive within the experimental duration. The dissolution rates normalized to the edge surface area (ESA) of smectite at a certain pH and temperature condition, therefore, had a constant value independent of the particle size, whereas the dissolution rates normalized to the total surface area (TSA) varied with the particle size. These dissolution rates were consistent with those derived from wet-chemical data in previous studies. The anisotropic dissolution behavior was also observed along the ESA, that is, the retreat of dissolution fronts along the {110} faces was much faster than that along {010} faces. This difference can be explained by smectite dissolution under alkaline conditions being controlled by OH- attack, which is catalyzed by protonated Al-OH groups, on the bridging O atoms of both Al-O-Si sites, which locate only on the {110} surfaces, and [Al.sub.2]-O-Si sites on the {010} and {110} surfaces. The bridging O atoms of [Al.sub.2]-O-Si sites on the {010} surfaces are buried more deeply in the structure than those of Al-O-Si sites on the {110} surfaces, which would be more difficult to attack on the {010} surfaces. Keywords: AFM, in-situ TMAFM in liquid, smectite dissolution, kinetics, surface studies, smectite

Raman spectra in the range 80 to 4000 [cm.sup.-1] of wadsleyite II ([Fo.sub.90] with 2.0 wt% [H.sub.2]O and [Fo.sub.88] with 2.7 wt% [H.sub.2]O) have been measured in a diamond-anvil cell with solid rare-gas pressure-transmitting media to 51.4 GPa at room temperature. The ambient Raman spectrum of wadsleyite II is closely similar to wadsleyite modified with bands in frequency regions where the Si[O.sub.4] tetrahedral and OH stretching vibrations of hydrous ringwoodite occur. The most intense, characteristic wadsleyite II modes at 709 and 911 [cm.sup.-1] ([Si.sub.2][O.sub.7] and Si[O.sub.3] symmetric stretching vibrations, respectively) shift continuously to 51.4 GPa showing no evidence for a change in the crystal structure. A striking feature in the high-pressure Raman spectra of wadsleyite II is a significant growth in intensity in the mid-frequency range (300-650 [cm.sup.-1] at [10.sup.-4] GPa and 400-750 [cm.sup.-1] at 51.4 GPa) under compression accompanied by the appearance of new Raman modes near 40 GPa, perhaps a result of resonance electronic Raman scattering. In the OH stretching frequency range, the Raman spectrum of wadsleyite II exhibits at least six modes and their high-pressure behavior agrees with that of [Fo.sub.90] hydrous wadsleyite: OH stretching modes above 3530 [cm.sup.-1] remain approximately constant up to at least 21.8 GPa whereas OH modes at frequencies Keywords: Hydrous wadsleyite II, Raman spectroscopy, diamond-anvil cell, transition zone, high pressure

Diamond may form in the Earth's mantle by recrystallization of graphite, by precipitation from a C-beating fluid, or by reduction of carbonate. The latter mechanism could result from interaction with a reduced fluid or another phase that would accommodate the oxygen produced by the reduction. One possible such phase is a sulfide-bearing melt, given that sulfides are common inclusions in diamond. Experiments at 1300 [degrees]C, 6 and 7.5 GPa successfully reduced magnesite in the presence of a eutectic-composition Fe-S-O melt. Although graphite rather than diamond was produced by this reduction, these experiments demonstrate that this mechanism is a viable mechanism for reducing carbonate to carbon in the Earth's mantle. Keywords: Experimental petrology, high-pressure studies, igneous petrology, crystal synthesis

In the Monte Rosa area, Northern Italy, the assemblage garnet + phengite + quartz was formed in polymetamorphic metapelites from pre-existing biotite and plagioclase during an eclogite-facies Alpine metamorphic overprint. While phengite nucleated within plagioclase, garnet formed l0 to 20 [micro]m wide continuous rims along the original biotite-plagioclase interphase boundaries. Garnet formation involved diffusion of Ca-, Fe-, and Mg-bearing species across the growing rims. The garnet rims show an overall asymmetric compositional zoning and distinct nanometer scale chemical patterns across grain boundaries within the garnet polycrystal. The compositional patterns resulted from the interplay of diffusion along grain and interphase boundaries and volume diffusion. Individual garnet crystals are separated by low-angle grain boundaries, which are predominantly oriented perpendicular to the reaction rim giving rise to an overall palisade microstructure. Grain boundaries contain arrays of closely spaced channels about 2 nm wide, which are filled with an amorphous phase. These channels represent direct links between the garnet-biotite and garnet-plagioclase reaction fronts and provide pathways for fast diffusion. From numerical simulation of the observed chemical patterns, diffusion of Ca and Fe is inferred to have been 5-6 orders of magnitude faster within grain boundaries than through the interior of garnet grains. Although the amorphous grain boundary phase only takes up a small fraction (2-5 per rail) of the total volume of the garnet polycrystal, short-circuit diffusion along grain boundaries contributed substantially to material transfer across the growing garnet rim. Despite the presence of fast pathways, bulk diffusion was too slow to allow for chemical equilibration of the phases involved in garnet rim formation, even on a micrometer scale. Relying on published garnet volume diffusion data, [D.sub.gb] (where gb = grain boundary), is estimated to be on the order of [l0.sup.-(19-20)] [m.sup.2]/s at the estimated reaction conditions of 650 [degrees]C and 12.5 kbar, where [D.sup.Ca.sub.gb] is slower than [D.sup.Fe.sub.gb] by a factor of ten. Keywords: Garnet, high-pressure metamorphism, grain boundary, diffusion, TEM

Syntheses have been done at 2.5 GPa and 750 [degrees]C to examine the effects of varying the water content and composition of the solid starting mixture on the formation of glaucophane [[Na.sub.2][Mg.sub.3][Al.sub.2][Si.sub.8][O.sub.22][(OH).sub.2]]. Amphiboles of apparently ideal glaucophane composition, confirmed by electron microprobe analyses, were obtained by treating oxide or oxide-hydroxide mixtures with bulk water contents of 4-5 wt% for durations of about 400 h in multiple treatments with intermittent grindings. This water content is necessary to permit growth of amphibole while preventing the intervention of a sheet silicate, which was identified in this study as vermiculite. To maximize amphibole yields, multiple treatments with intermittent grinding are needed on account of the low water contents that reduce the reaction rate of the synthesis process. Calculation of the solubility curves of talc, jadeite, and glaucophane in log[[a.sub.Mg(OH).sup.+]/[a.sub.H.sup.+]] vs. log[([a.sub.Na.sup.+])([MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII])] space at 2.5 GPa and 750 [degrees]C shows that glaucophane has a very narrow field of stability without coexisting jadeite or talc. This same diagram can be used to illustrate that the growth of vermiculite relative to glaucophane is not an issue of metastability but of the activity of water. Keywords: Analysis, chemical (mineral), sodic amphibole, crystal synthesis, glancophane, experimental petrology, glaucophane synthesis, high-pressure studies, glaucophane synthesis, metamorphic petrology, blueschist facies

Single-crystal polarized Raman spectra (80 to 4000 [cm.sup.-1] at 4 [less than or equal to] T [less than or equal to]700 K) and powder IR spectra (1500 to 4000 [cm.sup.-1] at 50 < T < 300 K) were measured for two microporous zeolites natrolite, [Na.sub.16][[Al.sub.16][Si.sub.24][O.sub.80]] x 16[H.sub.2]O, and scolecite, [Ca.sub.8][[Al.sub.16][Si.sub.24][O.sub.80]] x 24[H.sub.2]O to determine the behavior of [H.sub.2]O molecules in the channels. Both IR and Raman spectra show intense O-H stretching and [H.sub.2]O bending modes derived from the hydrogen-bonded [H.sub.2]O molecule(s) in the channels. Using published crystal structural data for natrolite and scolecite, and a consideration of Raman mode intensities that are sensitive to the [H.sub.2]O orientation in the framework channels, the internal stretching and bending modes could be assigned. The Raman spectra also show lower energy lattice modes and, in addition, second-order scattering in the wavenumber range where O-H stretching vibrations occur. The stretching vibrations of [H.sub.2]O molecules of natrolite and scolecite are located between 3200 and 3700 [cm.sup.-1] and bending vibrations occur around 1650 [cm.sup.-1]. In the case of natrolite, two intense O-H stretching modes can be observed and also several weaker combination modes. The latter was used to derive a low energy external [H.sub.2]O translational vibration, T([H.sub.2]O), which is also observed directly in single-crystal Raman spectra. In addition, two [H.sub.2]O librational modes are located at about 440 and 500 [cm.sup.-1]. For scolecite, six O-H stretching modes are observed in the Raman spectra recorded at 4 K, but only five are found at room temperature in the IR or Raman. The single-crystal Raman spectra also show several second-order combination modes consisting of external and internal [H.sub.2]O vibrations. They permit the wavenumber of several T([H.sub.2]O) modes at low wavenumbers to be determined. These combination bands are analyzed based on their temperature behavior between 0 and 300 K. It is shown that the wavenumber of the [H.sub.2]O bending modes decreases with an increase of the H-O-H angle of the [H.sub.2]O molecule in natrolite and scolecite. The dehydration behavior of [H.sub.2]O in natrolite and scolecite was investigated by Raman measurements of the intensities of the O-H stretching modes at temperatures from 300 K to 570 K and 720 K, respectively. IR and Raman spectra, obtained over a large temperature range, permit one to obtain a better understanding of inner surface [H.sub.2]O-molecule behavior in microporous silicates and energetics and the behavior of hydrogen bonding. Keywords: Raman spectroscopy, IR spectroscopy, natrolite, scolecite, microporous materials, Hydrogen bonding, zeolites, [H.sub.2]O molecules

The energetics of magnetic and cation ordering have been modeled using an atomistic approach based on empirical exchange interaction parameters. The model has been applied to the study of magnetic and cation ordering in the ilmenite-hematite solid solution via Monte Carlo simulations, providing new insight into the effect of nanoscale microstrnctures on the magnetic properties of this system. The lowest energy state for intermediate compositions is an intergrowth of cation-disordered antiferromagnetic (AF) hematite and cation-ordered paramagnetic (PM) ilmenite, separated by mixed [Fe.sup.2+]/[Fe.sup.3+] 'contact layers.' The intergrowth carries a stable defect moment ('lamellar magnetism') due to the presence of uncompensated spins. The net magnetization is parallel to the spin alignment direction, i.e., perpendicular to the spin-canted magnetization of the AF hematite. Contact-layer spins are coordinated to fewer magnetic neighbors than bulk spins and thus disorder more rapidly on heating. This leads to a decrease of net moment with increasing temperature. A small net moment is present, however, up to the Neel temperature of the AF hematite phase. The maximum temperature for acquisition of a chemical remanent magnetization due to lamellar magnetism is 800 [+ or -] 25 K, corresponding to the temperature for the eutectoid reaction PM hematite [right arrow] AF hematite + PM ilmenite. If only cation interactions are considered, [Fe.sup.3+] and [Fe.sup.2+] in the contact layers become ordered so that [Fe.sup.3+] shares an octahedral face with [Fe.sup.3+] in the neighboring hematite layer and [Fe.sup.2+] shares an octahedral face with [Ti.sup.4+] in the neighboring ilmenite layer. If both cation and magnetic interactions are considered, however, an alternative ordering scheme is stabilized, whereby [Fe.sup.3+] shares an octahedral face with [Ti.sup.4+] in the neighboring ilmenite layer and [Fe.sup.2+] shares an octahedral face with [Fe.sup.3+] in the neighboring hematite layer. The model has been used to investigate the nature of exchange coupling between ordered/anti-ordered domains and disordered antiphase boundaries, with a view to elucidating the mechanism of self-reversed thermoremanent magnetization. Antiphase boundaries are enriched in Fe relative to the ordered/antiordered domains, with enhanced enrichment observed in simulations performed within the PM hematite + PM ilmenite miscibility gap. Monte Carlo simulations of magnetic ordering show no evidence of self-reversal in systems containing two equally well-ordered ferrimagnetic (FM) domains separated by Fe-enriched AF boundaries. Systems displaying partial long-range order, however, do display self-reversed magnetization. Partial long-range order is characterized by a mixture of highly ordered Ti-rich FM domains and poorly ordered Fe-rich domains with a weak FM moment. The magnetic ordering temperature of the poorly ordered Fe-rich domains is significantly higher than that of the highly ordered Ti-rich domains, and act as the 'x-phase.' Evidence in support of the proposed mechanism from neutron diffraction and transmission electron microscopy is presented. Keywords: Magnetism, microstructure, ilmenite, hematite

The [sup.14]C-PMMA impregnation of rock samples and mineral staining methods provide the connected porosity map and the spatial distribution of mineral aggregates, respectively. Combined image analysis of mineral and porosity maps allows quantification of the connected porosity distribution in rock-forming mineral aggregates. After the two maps have been superimposed numerically, the [sup.14]C-PMMA method provides an indication of the extent of pore connectivity for each pixel in the analyzed area, which can be used to obtain the porosity distribution as a function of modal mineralogy. When applied to undeformed and deformed Kivetty granodiorite samples from Finland, the method allows for a detailed analysis of the rock porosity. Porosity distributions related to the undeformed rock are unimodal and approximately identical to each other. On the other hand, porosity distributions of the deformed granodiorite are multimodal and vary significantly. Constituent porosity sets of the deformed samples were albite crystals free of alkali feldspar patches and alkali feldspar phenocrysts (average porosity, [??] = 0.21%), albite containing alkali feldspar patches ([??] = 0.59%), rapakivi albitic mantles ([??] = 1.15%), quartz ([??] = 0.39%) and mafic minerals ([??] = 5.8%). Moreover, the analysis indicates that the numerous micropores observed under SEM within alkali feldspar phenocrysts and albite crystals free of alkali feldspar patches are unconnected in 3D. Keywords: Petrography, connected porosity, new technique, [sup.14]C-PMMA method, image analysis, igneous petrology, granite