Minerals as Advanced Materials II

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Many important materials that dominate modern technological development were known to mineralogists for hundreds of years, though their properties were not fully recognized. Mineralogy, on the other hand, needs new impacts for the further development in the line of modern scientific achievements such as bio- and nanotechnologies as well as by the understanding of a deep role that information plays in the formation of natural structures and definition of natural processes.

It is the idea of this series of books to provide an arena for interdisciplinary discussion on minerals as advanced materials. Would you like to tell us about a lower price? If you are a seller for this product, would you like to suggest updates through seller support? Read more Read less. From the Back Cover This book is a collection of papers that are devoted to various aspects of interactions between mineralogy and material sciences. Springer; edition September 28, Language: Be the first to review this item Amazon Best Sellers Rank: Try the Kindle edition and experience these great reading features: Share your thoughts with other customers.

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Get fast, free shipping with Amazon Prime. As shown in Fig. More structure analysis are necessary to explain the processes in detail. Gas Release from Minerals Fig. Heide Charoite Charoite is an unusual mineral. It is probably due to a reaction of a limestone with a chemical unique intrusion. Its structure could only recently be determined 5. Whereas these findings are in accordance with the Fig. We believe that decomposition of carbonates from admixtures can be excluded.

Possibly, our present GRP results might indicate that the composition of charoite is even more complex than given in the already quite complicated formula given above — at least for the sample used in our study. New experiments with new samples are planned Fig.

There is a gap between data about the major and trace element and the volatile concentration in crystals of the majority of minerals. The release of volatiles allows the separation between alteration and pristine species in the crystalline solid. The kinetic of gas release by diffusion and by bubbling allow the separation between fluid inclusions, melting processes and solid decomposition. The qualitative composition and the maximum temperatures of the evolved gases are genetic indication. The different bonding of volatile species in the crystalline structure is visible on the basis of degassing experiments.

Heide Acknowledgements I would like to thank W. Depmeier for the inspiring and critical discussion. A high-temperature microporous silicate with occluded molecular species. J Therm Anal Calor Khomyakov The modern mineralogical nomenclature is based on the principle that each new mineral species within a given structure type is defined by the dominance of a different chemical element at at least one structural site compared to the known minerals of that type Nickel and Grice In realizing this principle, a major problem until recently was presented by zeolite-structured multicomponent minerals with variably occupied structural sites e.

In the theory of isomorphism, they are usually regarded as isodimorphic solid solutions whose end-members belong to different structure types Belov and Smirnova ; Filatov and Bubnova In the most general form, this idea can be formulated as a principle of duality in isomorphism, stating that the end-members of continuous solid solutions can belong both to the same or to several different structure types Khomyakov a. According to this principle, the entire diversity of second-kind berthollides observed in nature can be described as combinations of a limited set of stoichiometrically complete structural and chemical end-members, for which the terms structals and chemals, respectively, are proposed Khomyakov b,c.

Each structal corresponding to an experimentally determined structure type is characterized by an idealized structural formula with fully occupied sites, and each chemal is characterized by an idealized chemical formula with integer coefficients. The crystal chemical characteristics of each particular structurally characterized sample of a second-kind berthollide can be described by partial fractions of structals and mole fractions of chemals. Mineral species are defined by the combination of the structural and chemical end-members that dominate a solid solution.

Chemals and structals that are subordinate in the composition and structure of a solid solution A.

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Khomyakov may be considered when defining chemical and structural varieties of mineral species. One structural end-member dominating different solutions can represent combinations with different chemals dominating the same solutions; as a consequence, one structure type can represent a series of several different mineral species. A striking example of this type of berthollide is provided by eudialyte group minerals EGM. In recent years, this group has expanded to more than 25 species Khomyakov , , Extra-framework cations and anions are located in variablesized cavities of eudialyte structures, in which single-crystal X-ray diffraction indicates there are not only high-occupancy structural sites, but also a large number of closely spaced low-occupancy sites.

EGMs vary significantly both in the total number and in the composition of atoms occupying these sites. Given these and other crystal chemical features of the eudialyte group, when assigning its specific members to distinct structure types, the author was guided by the above general principle and the related notion of chemals and structals as independent end-members of solid solutions with a variable number and composition of atoms in structural sites.

On the basis of identifying the dominant structal in EGM structures, 24 approved members of this group were found to belong to 15 different structure types, named for minerals with precisely characterized structures. The remaining minerals are assigned to the carbokentbrooksite johnsenite-Ce and zirsilite-Ce and kentbrooksite andrianovite, feklichevite, ferrokentbrooksite, georgbarsanovite, khomyakovite, manganokhomyakovite, and taseqite structure types as distinct members of appropriate isostructural series based on the dominant chemal.

All the identified EGM structure types are homeotypic. EGMs contain about half the elements of the periodic table. Wide variations in their concentrations in most extra-framework sites and some framework sites coupled with a wide variety of EGM structure types make the eudialyte group truly unique in the number of possible mineral species. Hence, mineralogical and crystal chemical research on this group holds great promise for new mineral discoveries. To conclude, we address the question of whether it is useful to introduce the terms structals and chemals, which we propose for the two fundamental types of end-members of solid solutions with a variable number and composition of atoms in structural sites.

Initially, to define the specific nature of such solutions, we considered using the terms structural end-member and chemical end-member. However, this idea was abandoned because it was found that the term structural end-member is widely used in the Russian literature to refer to building blocks in the description of homologous series of minerals and its use in another sense would inevitably cause confusion.

The introduction of the two short terms with a clear meaning is fully justified by the complexity of the isomorphism phenomena described by them. The same can be said for the proposed principle of duality in isomorphism, reflecting the dual nature of the end-members of isodimorphic solid solutions. Eur J Miner Zap VMO 5: New ideas and conceptions in mineralogy Syktyvkar: Third international symposium mineral diversity: Structure and diversity of mineral world. Proceedings international mineral seminar, Syktyvkar: Two fundamental end-member types of solid solutions with a varying number and composition of atoms in the structural sites.

Can Miner 36 3: Gorelik, Andrew Stewart, and Ute Kolb 1 Introduction Most of the newly discovered mineral phases, as well as many new synthesized industrial materials, appear only in the form of nano crystals, with a size not sufficient for single-crystal x-ray structure analysis. The development of techniques able to investigate the structure of nano crystalline materials is therefore one of the most important frontiers of crystallography.

The most widespread technique providing relatively fast and well consolidated routes for structure analysis of bulk materials is x-ray powder diffraction XRPD. Nevertheless, XRPD suffers from intrinsic 1-dimension reduction of information that greatly limits its applicability in presence of peak broadening and overlapping. Peak broadening is usually caused by very small crystallites, namely less than 50 nm. Overlapping of peaks is problematic mainly for intensity integration, but in case of polyphasic mixtures or significant amount of impurities it can be critical also for cell parameter determination and reflection indexing.

The main advantage of using electron radiation is the ability to collect structural information from areas of a few tens of nanometres, i. This is possible because electrons have a stronger interaction with matter Cowley et al. Nevertheless, performing down to 0. Under these conditions, nearly all organic and most of inorganic materials suffer a fast deterioration due to beam damage. The necessity to orient the particle in order to record meaningful HRTEM images further increases the exposure time.

This may lead to a modification of the crystalline structure or to complete amorphization or sublimation of the sample Spence ; Reimer and Kohl ; Kolb et al. On the contrary, electron diffraction can deliver structural information at a comparable resolution with significantly lower radiation on the sample. Classical drawbacks of electron diffraction are the presence of dynamic effects and the incompleteness of intensity data sets.

Moreover beam damage could be still a major issue for many classes of materials, like organic or water-containing inorganic materials. All these problems derive basically from the instrumentation and the method used for electron diffraction data collection. In fact the conventional way of electron diffraction data collection is based on acquisition of oriented zones. Though, dynamic effects are maximized in oriented zones, and only a limited number of reflections are accessible namely only reflections that belong to lowindex zones.

Additionally, a long time is needed for orienting the crystal, operation that implies time consuming and longer exposure of the sample to beam radiation. The application of electron diffraction data for structure solution dates back to Rigamonti , but for a long time electron crystallography was considered of little use due to the presence of dynamic effects Cowley ; Lipson and Cochran Nevertheless, excellent results were achieved from data sets collected by the electron diffraction camera developed by Pinsker and Vainshtein in Moskow during Pinsker ; Vainshtein , The technique developed by these authors, named oblique-textured electron diffraction OTED , was able to solve a number of organic and inorganic phases, up to the localization of H atoms in the structure see for example Zhukhlistov et al.

Nevertheless, sample preparation for OTED measurements is highly problematic because diffraction takes place on many crystals which need to be oriented approximately in the same way. Pioneering structure investigations using electron diffraction data collected by a TEM i. In the following 30 years a growing interest for electron diffraction and crystallography has arose and both organic and inorganic structures have been extensively investigated Dorset In order to further reduce dynamic effects, the precession unit was invented by Vincent and Midgley Vincent and Midgley This device precesses the beam around a conical path.

Consequently, the sample is never fully oriented along a main axis and reflections are integrated by the precessing Ewald sphere. Electron diffraction has been frequently used in combination with x-ray powder data. A recent example of structure solution of nano crystalline materials combining electron diffraction with a priori crystallochemical information and HRTEM and XRPD data is reported by Baerlocher et al. This method has been successful for the solution of some complicate zeolite structures, but until now it cannot be considered a routine path for structure analysis, as any working case needs a specific, different approach.

Therefore, there is still a need for routine methods allowing the acquisition of more complete and close-to-kinematic electron diffraction data. ADT approach marks a radical change from the traditional way of electron diffraction data acquisition based on oriented zones. With the use of a small condenser aperture C2 of 10 mm it is possible to obtain a beam size of 50 nm with almost parallel illumination on the sample. Dedicated software allowing automation of data acquisition further reduces acquisition time and consequently beam damage Kolb et al. Setting an exposure time of 1 s per diffraction pattern, it is possible to collect a full tilt series with a total exposure time of 2 min.

Possibly beam damage can be further reduced using cooling conditions or slightly moving the beam around the crystal during the acquisition. After the acquisition, a stack of 2-dimensional non-zonal diffraction patterns is stored. Knowing the tilt axis azimuth, the 3-dimensional reciprocal space can be reconstructed and used for direct visualization of disorder, twinning and polycrystallinity.

Finally, reflections are indexed and intensities integrated. Because all reflections inside the available tilt range are sampled, ADT intensity data sets have a significantly higher coverage of reciprocal space than those obtained by conventional electron diffraction zonal acquisition. Reflection intensities integrated by ADT are expected to be more kinematic than those measured in oriented patterns, as they are collected off zone and dynamic effects are therefore drastically reduced.

Nevertheless a significant deviation from 44 E. The resulting data sets proved to be of extremely high quality and in the last 2 years a number of complicate structures have been solved ab initio by direct methods with a fully kinematic assumption Birkel et al. In doing that, we selected two known structures and performed for them a complete ab initio structure analysis. For structure analysis electron diffraction data were collected using ADT module Kolb et al.

For high tilt mm, corresponding to a resolution of diffraction data of 0. The precession angle was kept at 1. Ab initio structure solution was performed by direct methods implemented in the software SIR Burla et al. Least square refinement was performed by Shelx97 Sheldrick For both ab initio structure solution and structure refinement, a full kinematic approach was used I proportional to F2 and reflection intensities data were used without any correction for absorption or geometry.

Scattering factors for electrons come from Doyle and Turner Most of synthetic zeolites cannot be grown in crystals large enough for single crystal x-ray analysis. On the other hand structure solution from powder x-ray diffraction data is not straightforward as many zeolites tend to crystallize as intergrown polyphasic assemblies Thomas et al.

Despite some remarkable results Nicolopoulos et al. Therefore, structure solution of zeolites is often limited to 2-dimensional solutions and only T-sites are correctly identified Dorset et al. A third intensity data set was obtained merging the two data sets coming from the two tilts. As the two data collections come from the same crystal, a merging factor of 1 was used.

Some important parameters of the first tilt series and of the merged data set are reported in Table 2. Both these two data sets were used for structure solution, giving very similar results. In orthorhombic symmetry, space group Fdd2 was uniquely defined by automatic extinction analysis performed by SIR Selecting this symmetry, ab initio structure solution set converged nicely to the expected solution, with final R of In both cases all the ten non-hydrogen atomic positions were identified and correctly assigned by SIR Table 3.

The eleventh potential was significantly weaker height of 50, less than half of the previous one. The maximum deviation was Derebe were 0. Structural refinement was performed by Shelx97 without imposing any geometrical restraint or constrain and led to R1 of Average and maximum deviations from the expected positions were both shorter.

All the atoms had positive and reasonable thermal factors. Sodium titanate can be used in various applications, such as ion-exchanging materials e. Crystals of sodium titanate have platelet shape, with preferential orientation along the more developed face. Experimental cell parameters are reported in Table 5. The important parameters of the intensity data sets are listed in Table 6.

The structure was immediately factor calculated from Wilson plot U was 0. The first three potential peaks, significantly stronger than the following, corresponded nicely to the three expected independent Ti atoms of the structure. The following seven positions corresponded to the seven independent O atoms. Positions 11 and 12 were too close to other peaks to be taken into account, so they were considered as ghosts. Position 13 corresponded to the only independent Na atom 50 E.

Differences Andersson and Wadsley were 0. Structural refinement using Shelx97 performed without any geometrical restraint or constrain converged to a solution close to SIR output Table 8 , with a final R1 of After refinement the expected positions were 0. All atoms have positive and reasonable thermal factors. The main reason of this difference is related with the different crystal family of the two materials.

Natrolite structure has an orthorhombic symmetry reflection multiplicity 8 , while sodium titanate is monoclinic reflection multiplicity 4. Additionally, sodium titanate crystals have a strong preferential orientation, resulting in missing 00l reflections from intensity data set. On contrast, for natrolite all the three main directions are sampled.

For natrolite, merging two tilt series did not produce significant benefits in this specific case. Nevertheless, merging different tilt series can be of significant benefit in cases of lower symmetry and even a small percentage of reflections could be determinant for structure solution, especially if these reflections belong to a main direction. Finally it is worth to point out that the merging of two data sets was done using a merging factor of 1 and resulted in a very small increase of the Rsym from Indeed the two tilt series come from the same crystal and was then reasonable to assume no change in thickness.

Structure solution of medium structural complexity inorganic structure can be performed routinely even for materials considered beam sensitive for HRTEM or conventional zonal electron diffraction. Data collection by ADT module is significantly faster than conventional zonal electron diffraction acquisition. Ab initio structure solution can be performed with routines and software developed for x-ray crystallography. The whole procedure, from data acquisition to structure solution, is now close to the time scale of single crystal x-ray structure analysis.

Still, the strong deviation of reflection intensities from kinematical expected values, resulting in the high final residual of the solution, is problematic for structure refinement. Different kinds of deviation from kinematic values affect intensity data, as residual dynamic effects, lack of geometrical correction, a need for better recording systems, more accurate background modelling, more elaborated intensity determination e. Nevertheless the possibility of ab initio structure solution of complicate structures based on raw ADT data proves the high potential of this approach, and ample margins of improvement are achievable in the near future.

Therefore, we firmly believe the ADT approach will open up new possibilities for nanomaterial investigation and engineering. The work was supported by the Deutsche Forschungsgemeinschaft in the Sonderforschungsbereich J Appl Crystallogr J Chem Cristallogr Shmueli U ed International tables for crystallography, Volume B, reciprocal space, 2nd edn. Chem Eur J The use of potential-density histograms.

Part II—cell parameter determination. Cryst Res Technol Cornell University Press, Ithaca. Ab initio determination of a new MCM zeolite structure. Springer, New York Rigamonti R La struttura della catena paraffinica studiata mediante i raggi di elettroni. Gazz Chim Ital Johannes Gutenberg University, Mainz. Acc Chem Res Sov Phys — Crystallogr 1: Pergamon Press, Oxford 54 E.

Vincent R, Midgley PA Double conical beam-rocking system for measurement of integrated electron diffraction intensities. J Phys Chem B The structure of charoite with the crystal chemical formula K All chains run parallel to z axis and lie on the mirror plane. The chains are bonded by their apical oxygens to Ca,Na -octahedra bands, I. The columns of octahedra are joined by shared edges and build a block four octahedra wide.

The apical oxygens link two such blocks to form a continuous zigzag sheet parallel to cf. Additional, isolated blocks four octahedra wide are present composed of a double column and two single columns joined by common apical oxygens. The octahedrally-coordinated sites in charoite are predominantly occupied by Ca.

The dreier double chain forms a tubular unit together with two columns of Ca octahedra and four tetrahedra of the neighbouring tubular chain cf. This tubular unit has a window of 8-membered ring 8MR of terahedra in the plane parallel The smallest diameter of each tube is given.

The tubular dreier triple chain of charoite has three-fold symmetry cf.

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There are three symmetrically equivalent 8MR windows present in this chain. The dreier single chain is similar to that found in pectolite and the dreier double chain is of the type found in okenite Merlino One tetrahedron of this large tubular chain is connected to four other tetrahedra, thus its connectivity is more typical for tetrahedra in framework structures cf. This tubular chain has four 8MR windows of which two at a time are symmetrically equivalent. Horizontal Si2O7 groups of each chain connect the separate bands of Ca-octahedra in such a way that apical oxygens of Si2O7 groups of neighboring chains are joined to different apices of vertical edges of octahedral cf.

Therefore, adjacent chains are shifted relative to each other by half a translation along the z axis. All the chains have windows of 8-membered rings. The tubes in charoite exhibit free perpendicular to z axis between 2. The smallest free diameters effective pore widths of the channels are given in Fig. All three tubular units are achiral as they have a mirror plane Fig.

The cavity has four windows of 8MR of which two free diameters of 6. Charoite, as an Example of a Structure with Natural Nanotubes 59 The interior of the tube I associated with the bent dreier double chain has a higher occupancy. The sites inside this tube are not fully occupied. In general understandings it describes a nanoscale tube-like structure which can be found naturally in some minerals or be man-made from a variety of materials.

An overview of nanotubes and tubular-shaped materials in some mineral systems was given in Krivovichev Nowadays SiO2 nanotubes can be easily synthesized and have potential applications as nanoscale reactors Ogihara et al. Despite the fact that up to now SiO2 nanotubes are amorphous, crystalline SiO2 nanotubes maybe synthesized in the future and the tubular chains of charoite may then serve as possible examples.

Part I — data acquisition. Part II — cell parameter determination. Krivovichev S ed Minerals as advanced materials I. I structure of an A-1 polytype. Krivovichev S ed Minerals as advanced materials II. Pokropivny V Non-carbon nanotubes Review. Powder Metall Met Ceram Miner Zh 10 4: Exactly this type of submarine hydrothermalism has recently been discovered Koschinsky et al. All processes during phase separation, ascent, and final venting of the hydrothermal fluids at the seafloor run entirely under p-T-conditions within the vapour-liquid two phase field above the critical seawater curve.

Based on measured p-T-conditions vent site RL seems to run under p-T-conditions of the singlephase field of seawater, while sites SP and TP temporarily run under p-T-conditions of the vapour-liquid two phase field or at least very close to p-T-conditions of the C. Our understanding of fluid-rock interaction, pressure-temperature regimes, and temporal variability of hydrothermal systems has been dominated by studies at the EPR in more shallow water depths Hydrothermal Alteration of Basalt by Seawater and Formation.

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Moreover, the in situ-microanalysis of original but experimentally altered basaltic rock fragments, experimentally formed secondary mineral phases, and micro-volumes of experimentally produced hydrothermal fluids would furthermore allow derivation of element partitioning coefficients that are prerequisites for subsequent thermodynamic calculations. This systematic experimental approach has recently been performed in our laboratories. The experimental set-up and the starting material are illustrated in Fig.

Au-capsule smaller size as container of the starting materials basalt glass and seawater inside the Au-capsule ; c: The experimental conditions mimicked the p-T-conditions close to or within the vapour-liquid two phase field, i. As above-mentioned the main emphasis of the present contribution is on the altered basaltic rock fragments and the secondary mineral assemblages. Representative aliquots of the experimental solid charges were therefore mounted in epoxy and polished for analysis by electron microscopy.

Visual intuitive alteration and mineral growth phenomena were studied by optical and digital photomicrographs, the latter acquired by backscattered electron detection on the JEOL RL electron microprobe. In the following the visual intuitive alteration and mineral growth phenomena will be correlated with the experimental parameters run duration, temperature, pressure, and water-to-rock ratio of the starting material and with the changes in major and minor element chemistry. In general, the alteration phenomena are quite divers. Formation of veins is common. The veins criss-cross the glass fragments.

Figure 4a is a detail of an optical photomicrograph of a representative sample that Hydrothermal Alteration of Basalt by Seawater and Formation. The degree of alteration increases from the rim to the centre. The outer heavily altered parts do have the tendency to peel off not shown in Fig. Most glass fragments are opaque and reddish-brown or green in colour, some fragments have still unaltered centres.

Formation of secondary minerals is also common. Figure 4b shows as an example idiomorphic plagioclase radial arranged as spheres at the emersion point of the veins. The experimental pressure and temperature conditions are within the single-phase seawater field. Areas of glass fragments of the shortest experiment Fig. These regions are side by side to areas that are completely nerved by veins centre part of Fig. All veins are chemical heterogeneous and not related to mineral chemistries. The degree of alteration increased at the 3 day experiment Fig.

This is also the case for the 7 and 10 day experiments Fig. As alteration progressed, larger regions of homogeneously altered glass are formed. The lack of significant changes in optical and chemical appearance of alteration as 66 C. All these basaltseawater interaction experiments were run at conditions of the vapour-liquid two phase field.

The alteration textures are again similar. The only differences are the distribution and the progress of alteration within the glass fragments. Chemical analyses of the altered regions in the lowest temperature experiment show Calcium loss. These low Ca content regions adjoin to regions composed of microcrystalline phases. Hydrothermal Alteration of Basalt by Seawater and Formation. Numbers within the images indicate spots of representative chemical analyses, that are listed in Table 1 3.

All experiments in Fig. Both sets had a constant run duration 10 days and water-to-rock 68 C. The pressures varied from to 4, bar in Fig. The degree of alteration of the glass fragments increases with increasing pressure in both sets of experiments. These unaltered regions are surrounded by an emerging first alteration zone of about mm width 2 in Fig. This first zone is characterized by low CaO and SiO2 contents concentrations drop by 7—8 wt.

The first alteration zone borders on a narrow, only 20 mm wide zone 3 in Fig. This second alteration zone is even more depleted in Ca and Si, but enriched in Fe, Mg, and Na compared to the unaltered regions, see chemical analysis of 3 in Table 1. The outermost region of the post-run charge at bar exists of heterogeneous and very fine grained textures. No reasonable meaningful chemical analyses of these textures were possible due to particle sizes of less than 1 mm.

At a pressure of bar Fig. No unaltered regions do exist anymore. At a pressure of 1, bar Fig. Besides these heterogeneous regions up to 1 mm large homogeneous areas formed that appear greenish in color under reflected light. Chemical analyses of these homogeneous areas point to high water and Mg contents and low Si and Ca contents.

A representative analysis is given as 4 in Table 1 see Fig. Following the terminology of Seyfried and Mottl rock-dominated experiments with water-to-rock ratios of 10, 5, 2. Backscattered electron images of the rock-dominated experiments are compared in Fig. All rock-dominated experiments show similar alteration phenomena. The number within a indicates the spot of a representative chemical analysis, that is listed in Table 1.

The still unaltered regions border on glassy areas that are leached in regard to Ca. These areas are surrounded by heterogeneous and very fine grained regions that consist of microcrystalline phases 9 in Fig. The chemical compositions of the microcrystalline phases 9 of Table 1 are similar in chemistry to the heterogeneous and very fine grained regions of the other experiments see e. Similar alteration phenomena can be observed in the post-run charges of experiments with water-to-rock ratios of 5 Fig.

Minerals as Advanced Materials II (Paperback)

Although the unaltered region is significant larger compared to the experiments with water-to-rock ratios of 10, areas with different degrees of alteration do already exist: This Ca poor area merges into an area with progressive increase of Ca towards the outside margin of the glass fragment that was in direct contact with the fluid during the experiment. The increase of Ca is accompanied by an increasing frequency of occurrence of microcrystalline phases. A simultaneous increase of the Ca content with the fraction of microcrystalline phases towards veins or cracks can also be observed in these glass fragments as some post-run glass fragments have veins or cracks.

The veins are sporadically dispersed and are different in chemistry compared to the veins that occurred at higher pressure and that formed vein networks. In experiments at even more fluid-dominated conditions, i. The Ca content in the altered regions than increases together with the fraction of microcrystalline phases towards veins or cracks. This is nicely illustrated in Fig. Macroscopically, the post-run glass fragments are lucent and more or less colorless. This is in stark contrast to the starting basaltic glass that is dark brown to black in color and to all other altered postrun glass fragments that are opaque reddish-brown or green.

Iron-rich phases formed as layers at the outside margin of the glass fragments. The iron-rich phases are oscillating with heavily altered glass layers. The homogeneously altered glass is relatively enriched in FeO 7 wt. Not shown in the profile is the significant content of water that is present in the homogeneously altered glass region as well as in the heavily altered glass layers.

The observed V- and U-shaped distribution patterns of Mg and Fe might therefore be attributed to leaching processes within the amorphous glass structure and not to a solid state solution-precipitation reaction as the controlling process. This hypothesis is strengthened by the observation of Mg increase in the altered glass towards the outside margin of the glass fragment that was in direct contact with the fluid during the experiment.

As secondary minerals are absent at the outside margin of the glass, the Mg increase points to incorporation of Mg from the fluid into the amorphous glass structure without formation and therefore involvement of secondary minerals at the outer rim of the glass fragment. Plagioclase is found in all post-run charges in varying quantities and sizes.

The plagioclase crystals appear either as columnar crystals about 40 mm wide and up to mm long columns or spherically grown with diameters of — mm. The columnar crystals are observed in all post-run charges and crystallize on the surface Fig. The numbers within the images indicate spots of representative chemical analyses listed in Table 2 74 C. The plagioclases are homogeneous in composition. Analysis 10 of Table 2 represents a chemical analysis of a homogeneous columnar plagioclase see Fig. In experiments at higher pressures pyroxenes as secondary minerals are totally absent.

The pyroxenes appear either as bottle-green, columnar pyroxenes Fig. Pyroxenes of both groups are enclosed by amphibole crystals. The radial arranged acicular pyroxenes are either grouped to larger spheres or they formed felts of pyroxenes Fig. Small plates of pyroxenes Fig. All pyroxenes are clinopyroxenes. The diopside content ranges from Di35 to Di60, with most pyroxenes having a diopside content of slightly less than Di The bottle-green pyroxenes have low Al and high Si contents Al2O3: BSE image of bottle-green, columnar pyroxene centre, 13 enclosed by amphibole 14 ; c: BSE image of radial arranged acicular pyroxene enclosed by amphibole; e: Chemical analysis of 13 and 14 are listed in Table 2 Radial arranged acicular pyroxenes have higher Al2O3 concentrations 2—7 wt.

Amphiboles exclusively formed as outer covers of pyroxenes. In analogy to the pyroxenes, the amphiboles can also 76 C. This part of the study focuses on the hydrothermal alteration of basalt, newly formed, i. Various alteration phenomena are observed in all post-run charges. The degree of alteration of basalt depends on parameters like run duration, temperature, pressure and water-to-rock ratio.

With increasing degree of alteration of basalt not only the bulk chemistry of the glass but also the former amorphous glass structure changes and gets replaced by heterogeneous microcrystalline phases. The observed newly-formed minerals in the post-run charges, namely plagioclase, clinopyroxene, amphibole, anhydrite, iron ore phases, and probable smectite, are typical secondary minerals as described in the review article by German and Von Damm The knowledge of the alteration phenomena of the basalt and the newly formed secondary minerals helps to better understand the natural alteration processes of oceanic crust.

In combination with the derived water-rock partitioning behaviour of transition metals and REE the hydrothermal alteration of basalt and consequential formation of secondary minerals, including the REE pattern of newly formed minerals, will add to our knowledge of basalt-seawater interaction processes and will improve our understanding of transport reactions and element fluxes during ascent in hydrothermal systems that run at extreme temperatures and great water depths. Acknowledgements The authors are grateful to P. Kluge for laboratory assistance and to A.

Fehler for excellent preparation of polished sections of very tiny samples. Geochim Cosmochim Acta Amer J Sci J Geophys Res Earth Planet Sci Lett Abstracts Hajash A Rare-earth element abundances and distribution patterns in hydrothermally altered basalts — experimental results.

Contrib Miner Petrol Insights as to chemical processes in near-shore ridge-flank hydrothermal systems. Experimental results for major and minor components of seawater. The role of anhydrite in controlling highly variable distribution patterns. Maslova In , the share of Russia in the world mineral output amounted to 8. Mineral processing at mining, dressing and chemical plants is known to be accompanied by the formation of solid and liquid wastes of both natural and synthetic origin.

Stored in tailing dumps, theses wastes pose a serious environmental hazard. At the same time, mineral components of the tailings can either be turned into natural geochemical barriers, preventing the dissolved toxic elements from escaping into the environment, or converted into valuable engineering materials Brylyakov et al. This issue has been recently addressed at Kola Science Centre by developing a set of innovation technologies whereby reject materials from technogenic deposits are converted into fertilizers, tanning and cleaning agents, pigments, and concretes. Moreover, the research has been focused on joint processing of natural products with electronic and metallurgical wastes Gerasimova and Nikolaev Table 1 provides data on chemical composition of major mineral tailings accumulated at enterprises operating in Kola Peninsula and North Kareliya.

One of the promising trends in mineral recovery is their application as adsorbents Gerasimova and Maslova Table 2 demonstrates the data on the removal capacity of some of the magnesium-silicate minerals of the Kola Peninsula suggesting their applicability as natural adsorbents of toxic elements Rakaev et al. Since the structure of sungulite like that of talc is laminated, fine grinding can turn it into filler for rubber compounds Gerasimova and Nikolaev Table 3 presents the relationship between the surface area and removal capacity of titanite and apatite — minerals from apatite-nepheline ore concentration Fedorov et al.

The surface area was increased through mechanical activation in a vibratory mill. By destroying the apatite grains via grinding, the surface is ionized, increasing the calcium ion-exchange capacity accordingly Gerasimova et al. The research also included the removal capacity of the anortosite mineral. The material constitution of the sample is given in Table 4. With diminishing of the mineral particles size, the sorption of non-ferrous metal cations increases Table 5. Apparently, the diffusion of coarser iron and copper cations into the defective surface layer of the particles is hindered, so that their removal capacity is lower than that of nickel and cobalt cations.

The spent mineral sorbent can be recovered by high-temperature processing. By this procedure, the adsorbed components are transferred to the insoluble state by forming compounds of the spinel type, colouring the product in different shades. Recovered sorbents are used as functional fillers for building and paint-and-varnish materials Gerasimova and Shchukina The adsorption of the oxotitanium IV cation on the flaky mica particles has been investigated.

Smaller flake sizes uptake greater substance quantities. These findings were used when developing a technology of pearl pigments, where the principal operation consists in adsorbing on the mica particle surface of the negatively charged oxotitanium IV cation. After being treated under conditions described above, the mica particles develop a surface charge facilitating the physico-chemical processes, whereby fine hydroxide layers are formed on them Fig.

We have proposed an original method for depositing hydroxide coatings, based on electrodialysis of titanium salt solutions iron, cobalt, etc. The process occurs at a low current density at electrodes 0. The hydroxide nanocoating formed on mica particles is consolidated by heat treatment to remove water and form the oxide shell crystal structure.

The electrochemical method underlying the mica preparation and used for the nano-coating deposition onto mica particles, makes controllable both the process proper and consumer properties of the target product Gerasimova et al. The possibility of producing from titanite mineral of pigment fillers for building and paint-and-varnish materials, and plastic has been investigated Fedorov et al.

Another result of dispersing is changed surface layer morphology due to ionization and amorphization Fig. As displayed in the desorption isotherm, the average pore diameter is The pore system on the particles dispersed in a vibrating mill the crushinggrating method is mostly represented by wide mesopores. The powder obtained by splitting in an impact-centrifugal mill has lower surface area indices 1.

All diffractograms are practically identical. The energy variance analysis has shown that the greatest transformations on the surface of the three samples compared are created by the attrition method. The intensity of Si response is over , that of Ca — , whereas after crushing these indices diminish to and , respectively. This is indicative of a high degree of amorphization in titanite particles Fig.

The findings presented here suggest the possibility of turning minerals and technogenic mineral wastes of the Kola Peninsula into engineering products such as sorbents, pigments and various fillers. The research has involved physical and chemical properties of both starting and dispersed minerals and the effect of their surface properties on adsorption ability of the materials.

It has been suggested that spent mineral sorbents can be utilized in the production of pigments and fillers of a broad colour range. J Water Purif Prep Suppl 4: Ecol Aspects Ind Prod 2: Paint Lacq Mater Appl 6: Paint Lacq Mater Appl 2—3: Chem Sustain Dev 1: Zhitova 1 Introduction Layered double hydroxides LDHs constitute an important group of materials with many applications ranging from catalysis and absorption to carriers for drug delivery, DNA intercalation and carbon dioxide sequestration Rives ; Duan and Evans Structural features of LDHs such as cation ordering, charge distribution and polytypism have an immediate influence upon their properties and have been under extensive experimental and theoretical investigations recently.

Different distribution of Al in a Mg hydroxide matrix also results in different charge distribution in the interlayer, which is critically important for intercalation reactions. Another area of interest in LDHs is the theory of the origin of life on Earth. Bernal , first proposed that minerals played a crucial importance in the origin of life and, along this line, Cairns-Smith suggested that clay mineral S. Petersburg State University, University Emb.

Due to excellent intercalation properties of clays, they accommodated in their interlayers variety of biologically active molecules that took over replication mechanisms from mineral crystals and transferred them to biological systems. In particular, he noted that LDHs easily form as as hydration products at ocean weathering of basalts, at serpentinization, etc.

According to their proposal Fig. Information is stored in LDH by the arrangement of trivalent cation sites. In the model shown in Fig. Thus the arrangement of the positive sites in the next layer will be exactly complementary to that of the previous layer. In the absence of stacking faults, defects and impurities, the alternating sequences of bit strings will propagate along the direction perpendicular to the layers.

When LDH crystal gets too large and cleaves, it will replicate itself either by splitting or by epitaxial growth of another crystal. If the proposed mechanism is realized in natural systems, it can be exploited by humans under laboratory conditions for creation of new subnanometer matrices for information storage and transfer. Thus the purpose of this contribution is to investigate possibility of this mechanism on the basis of current knowledge on natural LDHs.

First, we briefly summarize basic chemical and structural factors affecting chemical and structural diversity of LDH minerals. Then we shall discuss the reliability of cation ordering in the information transfer and storage on the basis of our recent experimental studies in this field.

Structure and Chemistry There are at least 38 minerals that can be considered as direct analogs of LDH materials with octahedrally coordinated metal cations Table 1. The main factors affecting their chemical diversity are: Chemical nature of interlayer anions and cations if any: Another important aspect of the crystal chemistry of LDHs is polytypism. In the plane perpendicular to the direction of layer stacking, cations and anions may occupy three distinct sites: A, B and C similar to the sites of spheres in closest packings. The upper A, B, C and lower a, b, c case symbols are reserved for positions of hydroxyls and cations, respectively.

For instance, if hydroxyl anions of the layer are in the A and C sites, the cations occupy the b sites, and the layer has 90 S. P-type interlayer or octahedra c: Otype interlayer a structural formula AbC Fig. Since positions of the cations within the layer are uniquely determined by the hydroxyl positions, they can be omitted.

Stacking of two layers may result in formation of two different types of interlayers Fig. In the case when upper hydroxide sheet of the lower layer and lower hydroxide sheet of the upper layer have the same notations e. This type of Natural Double Layered Hydroxides: In the case when upper hydroxide sheet of the lower layer and lower hydroxide sheet of the upper layer have different notations e. Using this simple and elegant scheme of notations, Bookin and Drits derived all two- and three-layer LDH polytypes and six-layer rhombohedral polytypes and calculated their powder X-ray diffraction patterns.

For instance, there are exactly three two-layer polytypes,. Out of these three polytypes, 2H1 polytype appears to be the most common in minerals it is obviously one observed for manasseite. In this polytype, all cations occupy the b sites and all interlayers are of the P-type. Among three-layer polytypes, the most common is the 3R1 polytype that has the structure.

On the basis of the nomenclature proposed by Bookin and Drits , Bookin et al. In contrast, in sulfate-bearing LDHs, the situation is more complex: The nomenclature was further illustrated and exemplified by Drits and Bookin Recent Results All the structural studies on synthetic LDHs deal with powder samples that prevent elucidation of such fine details of structure architecture as formation of superstructures due to cation ordering. Detection of the cation ordering is especially problematic in synthetic powder samples and, in particular, in synthetic quintinites Mg2Al-CO3 LDHs. On this basis, Richardson and Braterman concluded that a disorderly as-formed Mg2Al material through a solution-precipitation process transforms into material with regular Mg-Al order.

Al ratio of ca. It is worthy to note that, though other superstructures can also be theoretically constructed, the one shown in Fig. When compared to the monocation [M OH 2] octahedral layer Fig. In this mineral deposit, LDH-group minerals form at the late stages of hydrothermal activity as a result of secondary hydrothermal alteration of spinel crystals.

Chemical composition of the samples studied by the wave-length dispersion spectrometry using a Cameca MS electron microprobe and infrared spectroscopy provided the same within standard errors chemical formula, [Mg4Al2 OH 12] CO3 H2O 3. Single-crystal X-ray diffraction study revealed that the diffraction pattern of the samples quintinite-2H-3c and quintinite-1M was characterized by the presence of strong and sharp Bragg reflections and weakly discrete diffuse-like lines.

Whereas sharp Bragg reflections originate from basic layer stacking of metal hydroxide layers, weak reflections are indicative of formation of 3-D cation superlattices due to the Mg-Al ordering. Similar situation is observed also for quintinite-1M. Natural Double Layered Hydroxides: It is noteworthy that, in quintinite-2H-3c, Mg-Al ordering results in formation of threefold superstructure relative to the usual hexagonal 2H polytype, whereas, in quintinite-1M, cation ordering and superlattice formation results in dramatic reduction of symmetry: According to LDH polytype nomenclature see above , the layer stacking in quintinite-2H-3c can be described as.

The sequence of layers within the unit cell can be described as. There are three symmetry-independent octahedral cation 96 S. According to the Bookin and Drits 2. However, the sequence of the b positions if seen along the c axis is occupied by Mg and Al cations differently. This sequence can be written as [MgMgMgMgAlAl] or [Mg4Al2], taking into account that the content given in the square brackets corresponds to the c parameter repeat.

Considering possible relative positions of the 2-D Mg-Al cation array, one may distinguish exactly three different Mg2Al arrays related to each other by either a or b translations Fig. These arrays may be indicated as b1, b2 and b3 since all cations are in the b positions. Therefore the full description of the layer sequence i. The layer stacking in quintinite-1M Fig. However, because of the cation ordering, the situation becomes more complex and can be deciphered from the analysis of relative position of the 2-D Mg2Al cation arrays Fig.

First, it is obvious that cations in quintinite-1M are located in all possible sites, a, b, and c, so that the full description of the layer sequence should be written as. In the case of complete Mg-Al disorder, structure with this sequence would have a rhombohedral symmetry space group R-3m , but cation ordering results in symmetry reduction and formation of superstructure. As can be seen from 98 S. This results in disappearance of the threefold symmetry axis perpendicular to the layers and transition from rhombohedral to monoclinic symmetry. In order to distinguish between a, b and c positions occupied by Mg and Al cations in the Mg2Al array, we identify them as a1, a2, a3, etc.

Thus, the complete layer stacking sequence can be described as. It is of theoretical interest that the sequence.

According to the traditional nomenclature of polytypes, sample 2 should be called quintinite-1M, since it contains exactly one layer per monoclinic unit cell. The advantage of single-crystal diffraction is the possibility to analyse electron density distribution in certain areas of a structure. It can be seen that electron density maxima corresponding to the O atoms of carbonate groups are associated into almost continuous toroidal regions, which makes the refinement Natural Double Layered Hydroxides: Since there are no indications of any dynamic disorder effects in the structure e.

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