Conditions Of Mineral Formation Research Articles

Mineralogical-petrographic Features of Syenitic Migmatites of the Ilmenogorsky Miaskite Block (South Urals)

Syenitic migmatites of the contact of the Ilmenogorsky miaskite block are characterized by high (>500 ppm) contents of REEs, which are mainly hosted in fuorapatite and titanite of the leucosome. Apatite exhibits zoned and sectorial composition with decreasing REE and Si contents and increasing Cа, P, and F contents from central parts to the margins indicating the change in physicochemical conditions of mineral formation. The La/Nd ratios of REE-bearing fuorapatite indicate that apatite-1 formed from a F-bearing fuid in contrast to apatite-2 formed from an alkaline, F–CO2–SO3-rich fuid during albitization. The REEs and F released by alkaline metasomatism accumulated in late generation of REE–F-bearing titanite. Migmatization of rocks was accompanied by involvement of an alkaline F–CO2–SO3-bearing fuid.

Isotopic communication across the water – rock interface: Preservation in solids and signatures in fluids

Water – rock interactions are characteristically associated with isotopic fractionation between phases, yet their remains significant uncertainty in the degree to which these isotope ratios record the conditions of mineral formation or equilibration, and thus their fidelity as proxy records. Here, we present a novel generic modeling framework allowing sub-grid scale tracking of the isotopic signatures recorded in newly formed minerals over the timescale of precipitation and continued isotopic exchange between phases. We demonstrate that the surface area of the solid phase strongly influences the extent to which isotopes reflect the conditions of formation through time.

МАРГАНЦЕВОЕ РУДООБРАЗОВАНИЕ НА ПОДВОДНОЙ ВОЗВЫШЕННОСТИ БЕЛЯЕВСКОГО В ЯПОНСКОМ МОРЕ (ОБЗОР ЛИТЕРАТУРЫ И НОВЫЕ ДАННЫЕ)

The paper gives systematized and generalized information on manganese formations from the northern and southern summits of Belyaevsky Seamount in the Sea of Japan. This information shows that low-temperature hydrothermal fast-growing crusts are spread on the seamount widely. The crusts have bedded structure. Their textures are collomorphic and fibrous. The main ore minerals are birnessite and todorokite while the accessory minerals include vernadite, manganite, and pyrolusite. There are samples where ore minerals form veinlets in basalts and cement aggregates of clay minerals like smectite-hydromica. Silica minerals and barite crystallized at final mineralization stages. Micro-sized mineral phases of Cu, Zn, Sn, Ni, W, Cr, Ag, Ce, La, and Nd containing in the crusts and classifying by chemical composition as native, sulfide, sulfate, oxide, and intermetallic are obviously superimposed and meet high- and medium-temperature conditions of mineral formation. Crusts’ bulk chemical composition demonstrates abundances of Mn, Ba, Sr, and Li, as well as depletion of Fe, Al, Ti, and many trace elements. Positive Ce anomalies are likely to record the layers formed in the crusts due to the hydrogenic substance supply with hydrothermal ore formation processes being under attenuation.

Niobium Minerals As Indicators of a Genetic Link Between Tin-Bearing Zwitter and Lithium–Fluorine Granite of the Verkhneurmiysky Massif in the Amur River Region

Niobium minerals in zwitter and lithium–fluorine granite of the Verkhneurmiysky granitic massif in the Amur River region—fergusonite-(Y), euxenite-(Y), samarskite-(Yb), aeschynite, Nb-bearing wolframite— have been described and the similarity of their species composition established. The same-named and crystal-chemically allied minerals from zwitter and granite are characterized by similar complexes of such trace elements as W, REE, Mn, Fe, Pb, U, and Sc. A genetic link between Sn-bearing zwitter and Li–F granite is stated. Compositional varieties of niobium minerals in granite and zwitter reflect a change in the physicochemical conditions of mineral formation, when the magmatic stage is followed by a pneumatolytic–hydrothermal process. The postmagmatic evolution of niobium minerals is characterized by increased concentrations of Y, Pb, U, Fe and decreased concentrations of W, Ta, REE, Ti, Sc, and Th. The mineral occurrences in the western sector of the Verkhneurmiysky Cu–W–Sn cluster are appraised as promising for Nb, Y, and REE. Fergusonite, samarskite, euxenite, and Nb-bearing wolframite are indicators of rare metal mineralization.

Constraints on the behavior of trace elements in the actively-forming TAG deposit, Mid-Atlantic Ridge, based on LA-ICP-MS analyses of pyrite

The distribution of trace ore elements in different paragenetic stages of pyrite has been documented for the first time in the sub-seafloor of the actively-forming TAG massive sulfide deposit. Trace element distributions have been determined by in-situ laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) of pyrite formed at different stages of mineralization, and at different temperatures constrained by previously published fluid inclusion analyses. The data reveal a strong dependence on paragenetic stage, with distinct low- and high-temperature enrichments. Porous pyrite (and marcasite) formed at low temperatures (<300 °C) in the outer margins of the deposit is enriched in As, Ag, Tl, Pb, Sb, Mo, W, Zn, Ga, Ge, Cd, In, Te, Au, Mn, V, and U. Coarse-grained pyrite formed at higher temperatures (>350 °C) at the base of the hydrothermal mound and in the stockwork zone is enriched in Co, Se, Bi, Cu, Ni, and Sn. A number of different sub-types of pyrite also have characteristic trace element signatures; e.g., the earliest pyrite formed at the highest temperatures is always enriched in Co and Se compared to later stages. Ablation profiles for Co, Se, and Ni are smooth and indicate that these elements are present mainly in lattice substitutions rather than as inclusions of other sulfides. Profiles for As, Sb, Tl, and Cu can be either irregular or smooth, indicating both lattice substitutions and inclusions. Lead and Ag have mostly smooth profiles, but because Pb cannot substitute directly into the pyrite lattice, it is interpreted to be present as homogeneously distributed micro- or nano-scale particles. The behavior of the different trace elements mainly reflects their aqueous speciation in the hydrothermal fluids at different temperatures, and for some elements like Co and Se, strong partitioning into the pyrite lattice at elevated temperatures. Adsorption onto pyrite surfaces controls the distribution of a number of redox-sensitive elements (i.e., Mo, V, Ni, U), particularly in the upper part of the mound which is infiltrated by cold seawater. Where micro- or nano-scale inclusions of chalcopyrite, sphalerite, galena, or sulfosalts are present, there is still a strong temperature dependence on the inclusion population (e.g., more abundant chalcopyrite in the highest-temperature pyrite), suggesting that the inclusions were co-precipitated with pyrite rather than overgrown. However, at the deposit scale, the trace element distributions are also strongly controlled by remobilization and chemical zone refining, as previously documented in bulk geochemical profiles.The results show that pyrite chemistry is a remarkably good model of the chemistry of the entire hydrothermal system. For many trace elements, the concentrations in pyrite are highly predictive in terms of the conditions of mineral formation over a wide range of temperatures, from the stockwork zone to the cooler outer margins of the deposit. Calculated minimum concentrations of the trace elements in the fluids needed to account for the observed concentrations in pyrite show good agreement with measured vent fluid concentrations, particularly Pb, As, Mo, Ag, and Tl. However, significantly higher concentrations are indicated for Co (and Se) than have been measured in sampled fluids, confirming the strong partitioning of these elements into high-temperature pyrite.

Fluorides and Fluorcarbonates in Rocks of the Katugin Complex, Eastern Siberia: Indicators of Geochemical Mineral Formation Conditions

The paper discusses the chemical composition and parageneses of fluorides and fluorcarbonates in rocks of the Katugin Complex, with which a unique deposit of REE–Nb–Ta ore with cryolite is associated. In mineralogy and chemical composition, the rocks correspond to biotite, biotite–amphibole, arfvedsonite, and aegirine–arfvedsonite granites, which were regarded in earlier publications as granite-like metasomatic rocks. Aegirine–arfvedsonite granite contains a cryolite–gagarinite assemblage, which reflects depletion of Ca in the mineral-forming medium and enrichment in Na and F. Arfvedsonite granite is characterized by intergrowth of yttrofluorite with fluocerite and gagarinite, which indicates a relative enrichment in Ca and low CO2 content. Biotite granite is characterized by an assemblage of fluorite with titanite, apatite, and monazite as evidence for an elevated Ca concentration along with moderate F and P contents in the system. Neighborite, coulsellite, gagarinite, fluocerite, and tveitite-(Y) appear in biotite–amphibole granite along with replacement of annite with riebeckite and development of albite after microcline. All this indicates that a moderately alkaline Na-fluoride solution with a low Ca concentration affects biotite granite.

Crystal structure of modular sodium-rich and low-iron eudialyte from Lovozero alkaline massif

The structure of the sodium-rich representative of the eudialyte group found by A.P. Khomyakov at the Lovozero massif (Kola Peninsula) is studied by X-ray diffraction. The trigonal cell parameters are: a = 14.2032(1) and c = 60.612(1) A, V = 10589.13 A3, space group R3m. The structure is refined to the final R = 5.0% in the anisotropic approximation of atomic displacement parameters using 3742|F| > 3σ(F). The idealized formula (Z = 3) is Na37Ca10Mn2FeZr6Si50(Ti, Nb)2O144(OH)5Cl3 · H2O. Like other 24-layer minerals of the eudialyte group, this mineral has a modular structure. Its structure contains two modules, namely, “alluaivite” (with an admixture of “eudialyte”) and “kentbrooksite,” called according to the main structural fragments of alluaivite, eudialyte, and kentbrooksite. The mineral found at the Lovozero alkaline massif shows some chemical and symmetry-structural distinctions from the close-in-composition labyrinthite modular mineral from the Khibiny massif. The difference between the minerals stems from different geochemical conditions of mineral formation in the two regions.

Tectonophysics of hydrothermal ore formation: an example of the Antei Mo–U deposit, Transbaikalia

The Antei deposit of the southeastern Transbaikalian region is one of the largest uranium mines in Russia. It is hosted by the Late Paleozoic granitic basement of the Streltsovskaya caldera and was formed as a result of Late Mesozoic tectonothermal activity. Vein and stockwork–disseminated molybdenum–uranium mineralization at this deposit is controlled by zones of intense hydrothermal alteration, cataclasis, brecciation, and intense fracturing along steeply dipping faults, which acted as conduits for mineralizing fluids and hosts to the ore bodies. The upper edge of the ore-bearing zone is located at a depth of 400 m, and its lower edge was intersected at a depth of 1300 m from the day surface. The conditions of ore localization were determined using structural–geological and petrophysical studies coupled with numerical modeling of the effects of gravitational body forces at purely elastic and postcritical elastoplastic deformational stages. The dynamics of the tectonic stress field in the rock massif was reconstructed using the results of mapping of morphogenetic and kinematic characteristics of fault and fracture systems, as well as data on petrography and mineralogy of rocks and vein-filling material. It was shown that the fault framework of the deposit was formed in four tectonic stages, three of which took place in the geologic past and one of which reflects recent geologic history. Each tectonic stage was characterized by different parameters of the tectonic stress–strain field, fault kinematics, and conditions of mineral formation. The following types of metasomatic rocks are recognized within the deposit: high-temperature K-feldspar rocks and albitites (formed during the Late Paleozoic as the primary structural elements of a granitic massif) and Late Mesozoic low-temperature preore (hydromicatized rocks), synore (hematite, albite, chlorite, and quartz) and postore (kaolinite–smectite) rocks. The following petrophysical parameters were determined for all rock types: density, effective porosity, wetand dry-rock shear (S-wave), and compressional (P-wave) velocity. Ultrasonic measurements were made to obtain the dynamic Young’s modulus, shear modulus, bulk modulus, and Poisson’s ratio. The results confirm that all studied lithologies (host granites, K-feldspathized rock with albitites and hydromicatized rocks) have drastically different petrophysical parameters. These values were used as the basis for tectonophysical modeling of Late Mesozoic synore deformation induced by gravitational forces. It was shown that the domains of most intense deformation are confined to the intersections of submeridional fluid-conducting faults with sublatitudinal K-feldspathized and albitized zones, which acted as concentrators of external induced stresses. The formation of enriched ore shoots at these structural nodes can be explained by the suction-pumping of oreforming fluids by pipe-like (tubular) conduits under oriented stress. The deformation of K-feldsparthic rocks and albitites under stresses exceeding the elastic limit raised their fracture permeability due to cataclasis and brecciation and created favorable conditions for circulation of mineralizing fluids and precipitation of minerals. The use of tectonophysical modeling for the reconstruction of paleotectonic and fluid flow conditions during formation of hydrothermal mineralization allows a more precise evaluation of ore potential in deep levels and flanks of ore deposits.

Genesis of mugearites and benmoreites of Nemrut Volcano, eastern Turkey: Magma mixing and fractional crystallization of trachybasaltic melt

Presents detailed mineralogical and phase characteristics of trachybasalt, mugearite, trachydacite, and comendite samples from Nemrut Volcano in eastern Turkey, estimates of mineral formation conditions, and analyses of glasses from melt inclusions in olivine and rock matrix. Based on the analysis of the mineralogy and geochemistry of the rocks and mass balance calculations, the most feasible models of mugearitic and benmoreitic magma formation were proposed. The crystallization conditions of olivine, feldspar, and Fe-Ti oxides (titanomagnetite and ilmenite) were determined. Titanomagnetite and ilmenite were formed under the following conditions: 960-922°C, \(\Delta \log _{f_{O_2 } } \) NNO from −1.54 to −0.73 in the mugearite, 940-890°C, \(\Delta \log _{f_{O_2 } } \) NNO from −1.46 to −0.79 in the benmoreite, 870-845°C and \(\Delta \log _{f_{O_2 } } \) NNO from −2.11 to −1.82 in the trachydacite, and 705-667°C, \(\Delta \log _{f_{O_2 } } \) NNO from −2.48 to −2.18 in the comendite. Feldspars crystallized at 1150-950°C in the trachybasalt, 920-800°C in the benmoreite, and 760-720°C in the comendite. The temperature of melt inclusion entrapment in olivine (Fo75-40) from the trachybasalt, mugearite, benmoreite, and trachydacite was estimated as 1270-860°C. Except for the trachybasalt, partly resorbed phenocrysts and/or xenocrysts were observed in all the samples, which indicates their formation under nonequilibrium conditions. Mass balance calculations for rock compositions (FC, AFC, and FCA models) and mineralogical observations suggest that the magmas or melts of mugearitic and benmoreitic compositions could be produced by the fractional crystallization of trachybasaltic melt (mass fraction of melt F = 0.63–0.79), which assimilated a small amount of crustal material, as well as by the mixing of trachybasaltic (F = 0.16–0.45) and trachydacitic (F = 0.45–0.58) magmas in the presence of excess olivine, plagioclase, magnetite, and apatite (totaling 10–24 wt %). Pre-caldera comendites are enriched in Fe (4–5 wt % FeOtot) and trace elements compared with post-caldera comendites (2–3 wt % FeOtot). The analysis of the geochemical data and mass balance calculations indicated that the post-caldera benmoreitic magma could not be produced by the fractionation of trachybasaltic melt. This magma and corresponding post-caldera benmoreites have anomalously low Ba (46–54 ppm) and Sr (203–269 ppm) contents, which could not be obtained in the models of fractional crystallization of trachybasaltic melt accompanied by crustal assimilation. The compositions of post-caldera benmoreites and hybrid rocks of trachydacitic composition showing evidence for magma mixing (presence of xenocrysts from benmoreitic and comenditic magmas and compositionally variable glasses) were best reproduced by mixing trachybasaltic (F = 0.7-0.5) and low-Fe comenditic (F = 0.3–0.5) melts. Magma chambers with low-Fe comenditic melts appeared during the post-caldera stage owing to the fractional crystallization of pre-caldera trachytic and trachyte-comenditic magmas. Perhaps, the repeated eruptions of low-Fe comendites in the caldera and “rift” zone of Nemrut Volcano were related to the injection of benmoreitic magma into these chambers.

Cathodoluminescence Microanalysis of Amorphised Quartz

Journal Article Cathodoluminescence Microanalysis of Amorphised Quartz Get access MA Stevens-Kalceff, MA Stevens-Kalceff Institute of Mineralogy, TU Bergakademie Freiberg, Brennhausgasse 14, D-09596 Freiberg, Germany Search for other works by this author on: Oxford Academic Google Scholar J Götze J Götze Institute of Mineralogy, TU Bergakademie Freiberg, Brennhausgasse 14, D-09596 Freiberg, Germany Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 20, Issue S3, 1 August 2014, Pages 910–911, https://doi.org/10.1017/S1431927614006278 Published: 27 August 2014

粘土鉱物の鉱物学的特性と探査指標としての応用

Clay minerals widely occur as a product of the water-rock interaction in hydrothermal, diagenetic and weathering systems at the surficial part of the earth. They show highly diverse and systematic variations in mineralogical properties related to their localities and occurrences. The mineralogical properties of the clay minerals such as mineral chemistry, mixed-layer structure, polytype, particle size, etc., have been investigated to understand the environmental conditions of mineral formation. Recent studies on the chemical compositions and the particle size of clay minerals show that they can be linked to the physicochemical conditions and/or hydrogeological conditions of water-rock interactions performed in the surficial geologic systems. The chlorite geothermometer which links the chlorite compositions to temperature conditions of formation, is highly applicable as a physicochemical index of the water-rock interaction at hydrothermal systems. The particle size properties of clay minerals can be related to their crystal-growth mechanisms and to the hydrogeological conditions of mineral formations, in the water-rock interaction including kinetic reaction. These suggest that the chemical composition and the particle size property of clay minerals are usable as a mineralogical indicator also in exploration of natural resources hosted in the surficial parts of the earth.

Trace elements as indicators of the physicochemical conditions of mineral formation in hydrothermal sulfide systems

The three-mode distribution of trace-element (TE) concentrations is observed in accordance with three main forms of TE occurrence in mineral: structural, surficial, and phase (native TE phases). Minerals of hydrothermally synthesized pyrite–pyrrhotite–magnetite–greenockite assemblage in the presence of Au and Mn are studied. Discrimination of modes is made, using the method of statistical sample of analytical data for single crystals (SSADSC), which is based on the postulate that individual crystals can contain predominantly one of possible forms. This is supported by study of Cd modes of occurrence by element thermorelease atomic-absorption spectrometry. X-ray photoelectron spectroscopy and atomic-force microscopy were used to examine the surficial TE forms. It has been confirmed that the dependence of the TE content on the crystal size in the sample is mainly due to surficial nonautonomous phases absorbing TEs. The effect of correspondence of chemical-component forms on the surfaces of coexisting minerals is also corroborated. This phenomenon is not related to the mutual contamination of phases but is due to the induction of the corresponding states of chemical forms in coexisting nonautonomous phases. It is possible to obtain true coefficients of interface distribution, characterizing structural TE impurities. These coefficients differ strongly from apparent distribution coefficients calculated from the bulk contents of impurities, except for Mn in pyrrhotite and magnetite, where its structural mode is predominant. The results obtained show that TEs can be used as quantitative geochemical indicators, which help to obtain correct information about the parameters of mineral formation and TE contents in the fluid phase.

Geochemistry of organic matter in natural apatites of phosphorites according to EPR spectra of free radicals

The following organic radicals were identified by EPR spectroscopy in apatite from marine phosphorites (granular, nodular, shelly, and microcrystalline), supergene phosphorites (from ocean islands only), and modern and fossil biological materials (human dental enamel, fossil shark teeth, and pathogenic cardioliths): ĊH3, ĊH2-R, HOĊHR,(CH3)2-ĊR,3org, PO32−, P(OR)3, and perinaphtðenyl. Each textural and petrographic type of apatite corresponds to a specific model of organic radicals, which correlates with the type of organic matter (sapropelic, humic, guano, or collagen). The latter is controlled by the conditions of mineral formation, including climatic ones, and postdiagenetic (catagenetic) processes. A relationship was established between the EPR spectra of observed organic radicals and the valence state and structural position of impurity ions: (1) vanadium: V4+ (VO2+) in the Ca2+ II site or V5+ (VO4)3− → (PO4)3− and (2) uranium: U4+(UO2) in the Ca2+ II site or U6+ chemisorbed on the surface as UO22+

In situ boron isotope measurements of natural geological materials by LA-MC-ICP-MS

There are two main methods to determine boron isotopic composition. One is the solution method, in which boron is purified after the samples are dissolved in solution and the boron isotope ratios are determined by thermal ionization mass spectrometry (P-TIMS and N-TIMS) or multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS). The other is an in-situ analysis method, in which the in-situ boron isotopic ratios in minerals are analyzed directly using secondary ion mass spectrometry (SIMS) or laser ablation multicollector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS). In the in-situ analysis method for boron isotopes, the multifarious chemical purification and separation processes of the solution method are avoided, with increased work efficiency. In addition, the microzones and microbeddings of minerals can be analyzed in-situ to reveal the fine processes and conditions of mineral formation. In this study, using the standard-sample-bracketing (SSB) method, mass bias of the instrument and the fractionation of isotopes were calibrated, and the in-situ determination method of LA-MC-ICP-MS for boron isotopes was established. Through detailed analyses on a series of boron isotope standards and samples, a matrix effect was assessed but not detected, and the analysis results were in accordance with the formerly reported values or P-TIMS determined values, within the error range. The analytical results for IAEA B4 and IMR RB1 with relatively high boron contents were δ11B = −(8.36±0.58)‰ (2σ, n=50) and δ11B = −(12.96±0.97)‰ (2σ, n=57), respectively; the analytical result for IAEA B6 with relatively low boron content was δ11B = −(3.29±1.12)‰ (2σ, n=35). In-situ measurements for B isotopes were performed on geological samples such as tourmaline, ulexite, ludwigite, inyoite and ascharite, with the results consistent with those determined by P-TIMS, within the error range.

High-temperature electric conductivity of magnetite ore (magnetite) in connection with genetic properties of the deposit

995 By its degree of perfection, the crystalline structure of natural minerals differs from that of ideal crystals by the occurrence of many distortions and defects. These features of real crystals are variable for the same min� eral species from different deposits and belong to typo� morphic mineral properties [1, 2]. Moreover, “differ� ent generations of the same mineral, which are formed at successive formation phases and stages of the same deposit, always differ from each other in the composi� tions, shapes, and sizes of aggregates, structural parameters, and physical properties” [2, p. 17]. In the crystalline structure of real minerals that contain sev� eral cation species, their distribution through different positions in the lattice differs depending on the min� eral formation conditions and the subsequent thermal history. Most magnetite varieties exhibit a complex chemi� cal composition and contain various isomorphic admixtures. Being characterized by a defect spinel tex� ture, magnetite is very sensitive to changes in the min� eral formation conditions, which is reflected in its tex� ture and physical properties. The magnetite heteroge� neity is reflected in isomorphic replacements of Fe 2+ and Fe 3+ by several accessory elements. It is known that during the concentrating procedure, magnetite from ores of different genetic types behaves in different manners. This is to a large extent determined by differ� ences in its composition and texture [3]. When crystal� lizing in different thermodynamic and physicochemi� cal conditions, magnetite records genetic information on these conditions in its chemical composition and crystal structure. The physical properties of magnetite, which contain such information, are diverse and stim� ulate undying interest in the latter. New, previously unused properties are becoming known. Of impor� tance among typomorphic features are its electrical properties, features appearing at high temperatures and bearing information on crystallochemical pecu� liarities in the phase and structural state of matter

Quartz as a natural luminescence dosimeter

Abstract Luminescence from quartz is commonly used in retrospective dosimetry, in particular for the dating of archaeological materials and sediments from the Quaternary period. The phenomenon of luminescence is related to the interaction of natural radiation with mineral grains, by the activation of and subsequent trapping of electrons at defects within the quartz lattice. The latent luminescence signal (i.e. the trapped electrons) is released when the grains are exposed to stimulation energy in the form of light or heat. Despite the fact that quartz is most nominally pure SiO2, the mineral forms in several different geological settings, i.e. under different pressure and temperature conditions. The luminescence emitted from quartz is complex and shows a variety of different components with diverse physical properties. This complexity is explained by the variety of defects in quartz that are either intrinsic (e.g., Si and O vacancies) or related to impurity atoms (e.g., Al or Ti). The concentration of impurity-related defects is dependent on the conditions of mineral formation or subsequent alteration. Experimental data have shown that the luminescence properties of quartz are highly variable with geological source and vary even at a grain-to-grain level within a sediment. As a consequence, caution is needed when making any general statements about the luminescence properties of quartz. When using luminescence measurements as a dating technique, it is necessary to adjust the measurement procedures for each geological provenance. Furthermore, some quartz has luminescence properties that make it problematic, or even unsuitable, for certain applications. These problems can arise from low and changing luminescence sensitivity, thermal transfer of trapped electrons, thermal instability of the trapped electrons and low saturation dose. Reviewing the present knowledge reveals that insufficient information is available either to unambiguously link distinctive lattice defects with characteristic luminescence components, or even to explain problems observed in application studies by potential dynamics of the defects within the crystal. This paper gives some ideas on how future research could utilise innovative analytical tools to identify or map the distribution of lattice defects and how practitioners could relate lattice defects to measured luminescence properties of quartz.

First find of cerianite in zircons from metasomatites of the Terskii greenstone belt, Baltic shield

) is one of the most scarce rareearth minerals. Because of difficulties in discovery andidentification of this mineral, E.I. Semenov proposedconsidering cerianite as an object of nano (not micro)mineralogy [1]. Since its discovery in the 1950s, nomore than 20 reliable finds of this mineral (mainly inthe form of microscopic grains and microinclusions inother minerals) have been documented. Cerianite wasdiscovered for the first time in Sudbury (Canada) inthe carbonate dikes cutting across nepheline syenites[2]. In addition to Ce, cerianite contains isomorphicadmixtures of other LREE (La, Pr, Nd). Significantamounts of Th and other elements (Xe, Cs, Pb, Rh)were found in cerianite from pegmatites of East Antarctica [3]. Supergene cerianite occurs as a weatheringproduct of bastnaesite [1] and fluocerite [4], as well asin the weathering crust of different compositions [1,5–7]. In the oceanic Fe–Mn ores, cerianite isobserved as submicron films on apatite [8]. The formation of cerianite in granites is considered to berelated to hydrothermal alteration, accompanied byfluid leaching of Ce from monazite [9]. Cerianite associates with minerals and ores of noble metals: Au, Pt(Sukhoi Log deposit [10]); Au, Pd, and REE (oremanifestations of the Polar Urals [11] and others]).Overgrowths of cerianite of a few microns thick ondiamond phase were found in the carbonado fromBrasilia [12].Cerianite is a sensitive indicator of conditions ofmineral formation, because Ce is the only compatibleREE, which in natural conditions can occur not onlyin trivalent but also in tetravalent form. Cerianite isformed only in strongly oxidizing conditions, mainlyin alkaline solutions (fluids) [13].Submicron inclusions of cerianite were found by usin the zircon from twomica garnet–chlorite–quartz–plagioclase metasomatite (sample 2508) in the Terskiigreenstone belt in the southern framing of the Imandra–Varzuga structure (southeastern part of the KolaPeninsula). Complex isotopic–geochemical study ofzircons from metasomatites of the Terskii greenstonebelt allowed us to distinguish two stages of metamorphism (2680 and 2025 Ma) and two stages of metasomatism (2600 and 1800 Ma) [14]. Practically all zircons of different ages were completely or partiallymetasomatized, which caused their enrichment inREE (especially LREE), Th, U, Sr, and Ba, and formation of flat REEs with a reduced Ce anomaly.The structural features, majorelement composition of the zircons, and the composition of foreignmineral inclusions, if present, were studied in theregime of compositional contrast on a JEOL JSM6460LV scanning electron microscope equipped withan Oxford INCA detector at the St. Petersburg MiningInstitute. U–Pb dating of zircons from metasomatiteswas conducted on a SHRIMPII ion microprobe atthe Center for Isotopic Research, Karpinskii AllRussia Research Institute of Geology. The REE and traceelement composition of zircons was analyzed at thesame grains and points as U–Pb dating, on a CamecaIMS4f ion microprobe at the Yaroslavl Branch of thePhysicoTechnical Institute of the Russian Academyof Sciences.Zircon containing cerianite differs in the heterogeneous structure. Its weakly altered right upper part(point 2.1 in Fig. 1) retains traces of faceting and primary growth zoning. At the final stage of the Svecofennian metasomatism, most zircon was transformed with the formation of “patches” of irregularreniform shape, which form a band up to 100 µm insize with a characteristic dark tint in backscatteredelectrons (BSE) (point 2.2 and inset

Mössbauer study of Fe3+/Fe2+ ratio in amphiboles to search correlation with hydrogen isotope fractionation

There is a general lack of understanding of the hydrogen isotope fractionations between different experimental approaches both at higher and at lower temperatures of exchange. The complexity of bonding related with the hydroxyl ion in most hydrous minerals makes theoretical treatments rather difficult. Though some of the differences between experimental findings have recently been shown to be related to pressure effects that influence the hydrogen isotope fractionation properties of water, some other factors may also have significance. One of the major unknowns is the compositional control, especially the Fe-content and effects of variable Fe3+/Fe2+ ratios on hydrogen isotope fractionations between minerals and fluids (Suzuoki and Epstein, Geochim Cosmochim Acta 40:1229–1240, 1976; Chacko et al. 2001). We have studied a series of amphibole samples by Mossbauer spectroscopy, EPMA and TC-EA-IRMS to examine for possible correlations between D/H fractionation and Fe2+ to Fe3+ ratio/total iron content. Our measurements show that this correlation may exist for one particular origin of samples, but local conditions of mineral formation (most probably chemical composition and reactions accompanying the formation of minerals) may be more important in controlling the hydrogen isotope composition of minerals.

Experimental study of stability and crystallization peculiarities of tourmaline in hydrothermal conditions

Tourmaline is a polygenetic mineral and often occurs in pegmatite and pneumatolyte‐hydrothermal (metasomatic) and metamorphic rocks as a rock-forming mineral [1]. Wide varieties of the tourmaline chemical composition, often within the limits of even one deposit, make it a good indication of the changing physicochemical conditions of mineral formation. Crystals of tourmaline formed in rare metal pegmatites, greisens, and hydrothermal veins are characterized by the extremely great varieties of composition. More than 14 mineral varieties of tourmaline have been identified [2], which is connected with the peculiarities of its structure. Its generalized crystal chemistry formula is the following: XY 3 Z 6 Si 6 O 18 (BO 3 ) 3 V 3 W , where X— Na + ,

Mineral thermometry and the composition of fluids of the sodalite syenites of the Lovozero alkaline massif

In order to determine the conditions of mineral formation, a suite of sodalite syenite samples was investigated from the differentiated complex and in part from the eudialyte lujavrite complex of the Lovozero alkaline massif. The compositions of major and accessory minerals were analyzed using an electron microprobe. Various mineral geothermometers (Bt-Cpx, Amph-Cpx, and Amph-Bt) were applied to estimate the temperature of formation of clinopyroxene-bearing assemblages from the sodalite syenites. The temperature varied from ∼990 to 595–630°C, which reflects various stages of crystallization. The temperatures of formation of sodalite assemblages were estimated from the compositions of coexisting sodalite phases as 625–530°C and appeared to be in good agreement with estimates obtained by other mineral geothermometers. Based on the data on the composition and crystallization temperature of sodalites, the minimum concentration of salts (NaCl and Na2SO4) in the mineral-forming fluid was estimated as 10–20 wt % NaCl eq. for the two-sodalite assemblages and 1.5–3.0 wt % NaCl eq. for the nosean-bearing assemblages. The molar fraction of sulfur in the fluid was also estimated: 0.02 for the two-sodalite assemblages and 0.04–0.27 for the nosean-bearing assemblages.