Pitted impact deposits on Vesta show higher reflectance and pyroxene absorption band strengths compared to their immediate surroundings and other typical Vestan materials. We investigated whether heating to different temperatures for different durations of Vestan regolith analog materials can reproduce these spectral characteristics using mixtures of HEDs, the carbonaceous chondrite Murchison, and terrestrial analogs. We find no consistent spectral trend due merely to temperature increases, but observed that the interiors of many heated samples show both higher reflectance and pyroxene band I strength than their heated surfaces. With electron probe microanalysis, we additionally observe the formation of hematite, which could account for the higher reflectance. The presence of hematite indicates oxidation occurring in the sample interiors. In combination with heat, this might cause the increase of pyroxene band strengths through migration of iron cations. The effect grows larger with increasing temperature and duration, although temperature appears to play the more dominant role. A higher proportion of Murchison or the terrestrial carbonaceous chondrite analog within our mixtures also appears to facilitate the onset of oxidation. Our observations suggest that both the introduction of exogenic material on Vesta as well as the heating from impacts were necessary to enable the process (possibly oxidation) causing the observed spectral changes.

A detailed petrographic and mineralogical investigation of olivine-phlogopite micro-ijolite xenoliths from Oldoinyo Lengai, Tanzania indicates a complex evolutional history. These xenoliths consist of diverse textural subdomains characterized by minerals ranging from early-formed olivine, through diopside-hosted perovskite and phlogopite, to evolved aegirine-augite and titanite. Thermometry and mineral compositions in the subdomains suggest crystallization temperatures from 1070-970 degrees C to 850-700 degrees C at plutonic pressures and SiO2-activities controlled by perovskite-titanite equilibria. Double coronas are a characteristic textural feature of the olivine-phlogopite micro-ijolite, consisting of olivine cores surrounded by an inner clinopyroxene corona and an outer phlogopite corona. These double coronas might have formed during early magma chamber processes, including magma movement to a subsequent chamber resulting in dissolution of olivine with subsequent crystallization and accumulation of diopside and phlogopite. Diopside-aegirine-augite compositional zonation indicates several magma injections followed by cooling periods, during the formation of micro-ijolite groundmass. Mg# (80-83) and Ca (0.1-0.3 in wt%) contents of olivine together with the presence of primary melt inclusions in clinopyroxene, phlogopite, and nepheline indicate a magmatic origin from a possible parental olivine-nephelinite melt. There is evidence for subsolidus, or near-solidus, re-equilibration processes as indicated by the reaction of olivine with titanite forming symplectitic textures of ilmenite and diopside with minor zirconolite. Ti-exchange between phlogopite phenocrysts and other Ti-bearing minerals (perovskite, titanite, magnetite) resulted in similar to 750 degrees C equilibrium temperatures for phlogopite, which are much lower than mafic magmatic (>900 degrees C) conditions. Calculated subsolidus temperatures suggest crystallization of olivine-phlogopite micro-ijolites over a 10-20 km depth interval.

Dual-energy computed tomography (DECT) is an imaging technique that combines nondestructive morphological cross-sectional imaging of objects and the quantification of their chemical composition. However, its potential to assist investigations in paleontology has not yet been explored. This study investigates quantitative DECT for the nondestructive density- and element-based material decomposition of fossilized bones. Specifically, DECT was developed and validated for imaging-based calcium and fluorine quantification in bones of five fossil vertebrates from different geological time periods and of one extant vertebrate. The analysis shows that DECT material maps can differentiate bone from surrounding sediment and reveals fluorine as an imaging marker for fossilized bone and a reliable indicator of the age of terrestrial fossils. Moreover, the jaw bone mass of Tyrannosaurus rex showed areas of particularly high fluorine concentrations on DECT, while conventional CT imaging features supported the diagnosis of chronic osteomyelitis. These findings highlight the relevance of radiological imaging techniques in the natural sciences by introducing quantitative DECT imaging as a nondestructive approach for material decomposition in fossilized objects, thereby potentially adding to the toolbox of paleontological studies.

Mantle metasomatism is an important process in subduction zones in which fluids from the dehydrating oceanic slab interact with the overlying upper mantle resulting in a chemical alteration of the mantle. Consequently, this fluid-rock interaction may influence the mantle rock's physical properties such as the deformation behavior. In order to study element redistribution during mantle metasomatism in the laboratory, we used the simplified model reaction olivine + quartz = orthopyroxene, where olivine acts as representative for the upper mantle and quartz as proxy for the metasomatizing agent. We conducted piston-cylinder experiments at 1.5 GPa and 950 to 1400 °C, lasting between 48 and 288 h, on samples containing a mixture of quartz and one set of synthesized forsterite samples doped with either Co, Ni, Mn, or Zn. Additionally, we tested the influence of either nominally anhydrous or hydrous experimental conditions on the chemical distribution of the respective dopant element by using either crushable alumina or natural CaF 2 as pressure medium. Results of the chemical analyses of the recovered samples show dopant specific partitioning between doped forsterite and orthopyroxene independent of the confining pressure medium; except for the runs in which Ni-doped forsterite samples were used. The observed Ni- and Co-enrichment in forsterite samples may be used to identify mantle rocks that underwent mantle metasomatism in nature.

Amber, a natural polymer, is fossil tree resin derived from diverse botanical sources with varying chemical compositions. As such, all amber is susceptible to the effects of light, temperature, relative humidity, and oxygen, as well as exposure to certain chemicals, and will deteriorate over time in collections if left unprotected. Here we review approaches for the conservation, preparation, and imaging of amber specimens and their inclusions, and address indications and causes of amber degradation, as well as recommendations for a suitable storage environment. We also provide updated preparation and embedding protocols, discuss several techniques for imaging inclusions, and address digitization efforts. A stable storage environment is essential to mitigate or avoid deterioration of amber, which often manifests as crazing, spalling, breaking and colour changes. Based on previous conservation studies of fossil resins, we generally recommend storage in a climate-monitored environment with a relative humidity of ca. 50%, 18 degrees C, and stress that light exposure must be kept to a minimum. For stabilization and anoxic sealing, amber specimens should ideally be embedded in an artificial epoxide resin (EpoTek 301-2 or similar is currently recommended). Amber should not be treated with or stored in vegetable or mineral oils (even for a short time for examination or photography), or come into contact with alcohol, disinfecting agents, hydrogen peroxide, or other destructive solvents or mixtures, since any of these materials can irreversibly damage the amber. Most photography of inclusions for research and digitization purposes can be successfully accomplished using light microscopy. Scanning electron microscopy (SEM) is sometimes used to uncover fine details, but is an invasive method. However, X-ray based methods (utilizing micro computed tomography, or micro-CT) are becoming more frequently used and increasingly indispensable in the examination of minute internal structures of inclusions, and to fully visualize important structures in opaque amber. Micro-CT makes it possible to digitize an inclusion three-dimensionally, and thus enables digital specimen 'loans'. Light microscopal images are still widely used in the digitization of amber specimens and are an essential alternative to micro-CT imaging when resources or time are limited. Overall, due to the vulnerability of all fossil resins, we recommend that conservation of amber samples and their inclusions be prioritized.

The present study investigates for the first time a largely forgotten pyrotechnology for manufacturing artificial millstones for Persian windmills and querns from Islamic period Sistan, a region in southeastern Iran. The unusual characteristics of these materials result from melting a sand-clay mixture at high temperatures. A unique experimental and multianalytical method was developed to understand the heating-cooling regime for manufacturing artificial millstones and other technical details of their production. According to chemical and microstructural analyses, these materials were melted between 1150 degrees C and 1250 degrees C and kept there for a period of 14-20 h, to be subsequently cooled down by 10-50 degrees C/h. Our experimental results for reproducing the microstructure of these objects show that any other temperature regime would be unsuccessful for manufacturing a functional millstone for these huge windmills which are usually referred to as the first wind turbines in the history of technology.

Methodology and Archaeometry (MetArh) is an annual scientific conference organized since 2013 by the Department of Archaeology of the Faculty of Humanities and Social Sciences of the University of Zagreb, and the Croatian Archaeological Society. The goal of the conference is to entice interdisciplinarity, critical thinking, new insights and approaches as well as new theoretical frameworks in contemporary archaeological science. This, second edition of the conference Proceedings contains eight scientific papers from the 6th MetArh conference which was held at the Faculty of Humanities and Social Sciences of the University of Zagreb, from 6th - 7th of December 2018. Papers are focused on different aspects of archaeological methodology and archaeometry, including case studies from Croatia, Slovenia, Serbia, Greece and Russia. In order to create a volume of high scientific quality, each of the conference paper was reviewed in the peer review process in which the identity of both reviewers and authors, as well as their institutions, are respectfully concealed from both parties.

A unique collection of high-quality late medieval (fifteenth–sixteenth century) glazed and unglazed stove tiles from the northern part of the Carpathian Basin is of great interest to archaeologists and art historians. It is yet to be determined if these products, which are characterised by similar features, were produced in a single workshop, perhaps in Besztercebánya/Banská Bystrica (in present-day Slovakia), or in several workshops throughout the region. The first systematic multi-analytical investigation was carried out on the ceramic body and glaze of one hundred and seventeen tile fragments from six sites (Besztercebánya/Banská Bystrica, Fülek/Fiľakovo, and Csábrág/Čabraď in Slovakia; Salgó, Eger, and Szécsény in Hungary) using polarising microscopy, X-ray diffraction, electron microprobe, and Raman microspectroscopy analyses to determine the raw materials and production techniques used. Based on the petrographic characteristics, phase and chemical composition of the ceramic body, and the chemical composition and colourants of the glazes, the stove tiles can be classified into three primary groups. Tiles from different sites are different to each other, only the tiles from the Hungarian sites and from Fülek/Fiľakovo are similar. Thus, it is probable that the tiles were produced in several (at least three) workshops in the region from where they were then dispersed. The technological knowledge of the master(s) producing the polychrome Csábrág/Čabraď tiles with tin-opacified glazes was higher than that of the master(s) producing the other tiles. However, the exact location of the workshops as well as their existence through time is still in unknown.

The firing behavior of illite-based archaeological ceramics and corresponding firing conditions were investigated, in order to identify the pyrotechnology of ceramic production at archaeological sites in the North Caucasus (Russia, Bronze and Iron Age). Direct observations of the pyrometamorphic degree in the objects by scanning electron microscope (SEM), X-ray powder diffraction (XRD), Raman and Fourier-transform infrared spectroscopy (FT-IR) revealed the thermally induced localization of the redox state within a single object and its influence on the structural distortion, dehydroxylation and total collapse of illite in the ceramics. Fundamental approaches to illite dehydroxylation kinetics and numerical simulations of oxygen diffusion and heat transfer revealed that the firing temperature and time and thickness of the sample, reactivity between oxygen and ceramic pastes and porosity evolution played a decisive role in the firing behavior of the ceramics during the firing at the sites.

The New Caledonia Ophiolite hosts one of the largest obducted mantle sections worldwide, offering a unique opportunity to investigate key mantle processes. The ophiolite comprises refractory harzburgites, locally overlain by mafic-ultramafic cumulates, and minor lherzolites. Previous geochemical studies indicated that the lherzolites are akin to abyssal-type peridotites, while the harzburgites underwent multiple melting episodes in MOR and supra-subduction zone environments, followed by late stage metasomatism. In this work, Os isotopes, highly siderophile (HSE) and chalcophile element data are reported for the New Caledonia peridotites, in order to constrain the behaviour of these elements in abyssal-type and fore-arc mantle. The variably serpentinised lherzolites (LOI = 6.4-10.7%) yield slightly subchondritic to suprachondritic initial Os isotopic compositions (Os-187/Os-188(i) = 0.1273-0.1329) and subchondritic to chondritic Re/Os ratios (0.04-0.11). The gently sloping HSE patterns with increasing depletion towards Au show concentrations in the range of other lherzolites from MOR or continental setting. Sulphur contents are high and variable (202-1268 ppm), and were likely increased during serpentinisation. By contrast, Se/Te ratios and concentrations are within the range of primitive mantle (PM) values, meaning that these elements were not significantly mobilised during serpentinisation. Although displaying homogenous petrographic and geochemical features, the harzburgites are characterised by extremely heterogeneous Re-Os and HSE compositions. Type-A harzburgites exhibit subchondritic Os-187/Os-188(i) (0.1203-0.1266) and low Re/Os ratios (0.01-0.04). The strong IPGE-PPGE fractionations (Pd-N/Ir-N = 0.21-0.56), coupled with positive Pt anomalies and S-Se-Te abundances often below the detection limit, suggest high melt extraction rates, resulting in sulphide consumption and Os-Ru metal alloy stabilisation. Type-B harzburgites possess strongly fractionated, Os-Ir-Pt poor (Os = 0.003-0.072 ng/g, Ir = 0.0015-0.079 ng/g) and Pd-Re enriched patterns, associated with chondritic to suprachondritic measured Os-187/Os-188 (0.127-0.153). These characters are uncommon for highly depleted mantle residues. Interaction with an oxidised component does not appear as a viable mechanism to account for the IPGE-depleted patterns of type-B harzburgites, as calculated oxygen fugacities are close to the FMQ buffer (Log Delta FMQ = 0.35 to 0.65). The strikingly uniform mineralogical and geochemical features displayed by both harzburgite sub-types suggest that the different HSE patterns are not linked to their recent evolution, implying that subduction-related processes were superimposed on geochemical heterogeneous mantle domains, which exerted an important control on HSE behaviour during melt extraction and post melting metasomatism. We propose that the HSE characters of the studied peridotites reflect the presence of a highly heterogeneous mantle source with a long term (>1 Ga) evolution, possibly linked to the Zealandia formation. (C) 2019 Elsevier B.V. All rights reserved.

Recent advances in microscopy, scanning techniques and digital data processing have allowed image analysis of archaeological objects.In this study, 2D/3D image analysis will be applied for the main topics of ceramic pottery production: resource gathering, firing degree and shaping techniques.The basic images were acquired by the polarized light microscope, SEM and 3D µ-CT.The segmentation and parametrization of structural elements were performed by Matlab.In order to characterize ceramic pastes, shape parameters such as size distribution, circularity and sphericity of coarse sand grains provided quantitative information.Pore topology dominated by the clay/ceramic sintering can give qualitative and quantitative data for the pyrometamorphic degree of the ceramics.Sphericity, surface area, volume, Euler characteristic and curvature of open and closed pores are the possible parameters describing the topology and topological changes.They allow us to estimate the existence of various firing states.Shaping techniques of the ceramic body were identified by three-dimensional alignments of segmented pores and sand grains.A continuous and separate building of the structural part, hand shaping or wheel-shaping/thrown can be suggested by this method.Despite the heterogeneity in mineralogical and chemical composition, grain size distribution and firing state of most archaeological ceramics, it is expected that the direct measurement of the visual element and its parametrization enable us to identify various techniques employed for the prehistoric ceramic production.This method will contribute to reconstructing technological styles of prehistoric material production with easier and faster availability and accessibility.

Pyrotechnology for the prehistoric pottery has been an important subject for the study of ancient production technology and technological styles. However, heterogeneous characteristics in chemical and mineralogical compositions and massive amounts of ceramic sherds at most archaeological sites make it difficult to identify production technologies. In this study, SEM-EDS/WDS, XRD and transmittance and reflectance FT-IR techniques were employed step by step, in order to overcome these limitations. The serial combination of each method covers a macro-, meso- and micro-scale and it enabled us to identify the relationship between firing temperature, reducing or oxidizing atmosphere and thermally induced mobility of Ca and Fe. Numerous ceramic pottery sherds from two archaeological sites in the North Caucasus, Ransyrt 1 (Middle-Late Bronze Age) and Kabardinka 2 (Late Bronze/Early Iron Age) were investigated and compared to the ceramics found at Levinsadovka and Saf’janovo around the Sea of Azov, Russia (Late/Final Bronze Age) for this purpose. Morphological changes by sintering and transformation of indicator minerals such as calcite, hematite, spinel, gehlenite, quartz and cis/trans-vacant 1M illite provide temperature thresholds at 675, 700, 750, 950, 1050, 1100, 1300 °C. With the laboratory based FT-IR, vibrational changes in shape, wavenumber and intensity corresponding to Si-O stretching bands yield an order and classification of the ceramics with regard to firing conditions between the samples as well as the unraveling of temperature profiles within a single sample in a 100 µm scale. With this approach, the number of archaeological ceramics could be classified according to the pyrometamorphic transformation of heterogeneous ceramic composite materials. Combined with the archaeological contexts of each site, these results will contribute to the reconstruction of local technological styles.

Earth's only active natrocarbonatite volcanism, occurring at Oldoinyo Lengai (OL), Tanzania, suggests that natrocarbonatite melts are formed through a unique geological process. In the East African Rift, the extinct Kerimasi (KER) volcano is a neighbor of OL and also contains nephelinites hosting melt and fluid inclusions that preserve the igneous processes associated with formation of natrocarbonatite melts. Here, we present evidence for the presence of coexisting nephelinite melt, fluorine-rich carbonate melt, and alkali carbonate fluid. The compositions of these phases differ from the composition of OL natrocarbonatites; therefore, it is unlikely that natrocarbonatites formed directly from one of these phases. Instead, mixing of the outgassing alkali carbonate fluid and the fluorine-rich carbonate melt can yield natrocarbonatite compositions at temperatures close to subsolidus temperatures of nephelinite (<630-650 degrees C). Moreover, the high halogen content (6-16 wt%) in the carbonate melt precludes saturation of calcite (i.e., formation of calciocarbonatite) and maintains the carbonate melt in the liquid state with 28-41 wt% CaO at temperatures >= 600 degrees C. Our study suggests that alkali carbonate fluids and melts could have commonly formed in the geological past, but it is unlikely they precipitated calcite that facilitates fossilization. Instead, alkali carbonates likely precipitated that were not preserved in the fossil nephelinite rocks. Thus, alkali carbonate fluids and melts have been so far overlooked in the geological record because of the lack of previous detailed inclusion studies.

The recent advances in microscopy and scanning techniques enabled the image analysis of archaeological objects in a high resolution. From the direct measurements in images, shapes and related parameters of the structural elements of interest can be derived. In this study, image analysis in 2D/3D is applied to archaeological ceramics, in order to obtain clues about the ceramic pastes, firing and shaping techniques. Images were acquired by the polarized light microscope, scanning electron microscopy (SEM) and 3D micro X-ray computed tomography (µ-CT) and segmented using Matlab. 70 ceramic sherds excavated at Ransyrt 1 (Middle-Late Bronze Age) and Kabardinka 2 (late Bronze–early Iron Age), located in in the North Caucasian mountains, Russia, were investigated. The size distribution, circularity and sphericity of sand grains in the ceramics show site specific difference as well as variations within a site. The sphericity, surface area, volume and Euler characteristic of pores show the existence of various pyrometamorphic states between the ceramics and within a ceramic. Using alignments of pores and grains, similar pottery shaping techniques are identified for both sites. These results show that the image analysis of archaeological ceramics can provide detailed information about the prehistoric ceramic production technologies with fast data availability.

The formation of ordered particle arrays plays an essential role in nanotechnology, biological systems, and inorganic photonic structures in the geosphere. Here, we show how ordered arrays of amorphous silica spheres form in deeply weathered lithologies of the Great Artesian Basin (central Australia). Our multi-method approach, using optical and scanning electron microscopy, X-ray microdiffraction, Raman spectroscopy, and electron probe microanalysis, reveals that particle morphologies trace the flow of opal-forming colloidal suspensions and document syn-and post-depositional deformation. The micromorphology of amorphous silica pseudomorphs suggests that the volume-preserving replacement of non-silicate minerals proceeds via an interface-coupled dissolution precipitation process. We conclude that colloid flow and post-depositional shearing create but also destroy natural photonic crystals. Contrary to previous studies, our results indicate that purely gravitational settling/ordering is the exception rather than the rule during the formation of three-dimensional periodic sphere arrays in the highly dynamic colloidal suspensions of chemically weathered clastic sediments.

A detailed understanding of silica postdepositional transformation mechanisms is fundamental for its use as a palaeobiologic and palaeoenvironmental archive. Amorphous silica (opal-A) is an important biomineral, an alteration product of silicate rocks on the surface of Earth and Mars, and a precursor material for stable silica phases. During diagenesis, amorphous silica gradually and gradationally transforms to opal-CT, opal-C, and eventually quartz. Here we demonstrate the early-stage maturation of several million year old opal-A from deeply weathered Early Cretaceous and Ordovician sedimentary rocks of the Great Artesian Basin (central Australia). X-ray diffraction, scanning electron microscopy, and electron probe microanalyses show that the mineralogical maturation of the nanosphere material is decoupled from its chemical properties and begins significantly earlier than micromorphology suggests. Non-destructive and locally highly resolved X-ray microdiffraction (mu-XRD2) reveals an almost linear positive correlation between the main peak position (3.97 to 4.06 angstrom) and a new asymmetry parameter, AP. Heating experiments and calculated diffractograms indicate that nudeation and growth of tridymite-rich nanodomains induce systematic peak shifts and symmetry variations in diffraction patterns of morphologically juvenile opal-A. Our results show that the asymmetry parameter traces the early-stage maturation of amorphous silica, and that the mineralogical opal-A/CT stage extends to smaller d-spacings and larger FWHM values than previously suggested. (C) 2018 Elsevier B.V. All rights reserved.

Much of the Earth's dynamics is related to mineral reactions in the solid-state. Classically, this is referred to as metamorphic crystallization (Kretz, 1994). Based on the chemical compositions of the phases involved in a metamorphic mineral reaction, two basic reaction types may be distinguished. Reactions that involve only structural re-arrangements, while the compositions of the reactant and product phases are identical, are referred to as partitionless and 'polymorphic phase transformations'. If, in contrast, one or more reactant phases are replaced by one or more product phases with different compositions, this implies that chemical components are supplied to or removed from the reaction interfaces separating the reactants from the product phases. In the absence of advective transport via a fluid or melt, the necessary chemical mass transport can occur only by diffusion. Accordingly, this reaction type is partitioning and is referred to as 'diffusive phase transformation'. Some treatments of the kinetics of mineral reactions are based on partitionless polymorphic phase transformations and are reviewed only briefly in this chapter. However, because most metamorphic mineral reactions are partitioning diffusive phase transformations, the following discussion will focus mainly on this reaction type.In this chapter, three types of reactions that play a key role in metamorphic crystallization are addressed. During prograde metamorphism continuous supply of aqueous fluid by dehydration reactions may facilitate relatively rapid inter-crystalline diffusion so that a state close to chemical equilibrium on the scale of mineral grains and beyond may be attained resulting in 'porphyroblastic mineral growth'. Interface-reaction controlled and diffusion-controlled growth are two end-member models in the kinetics of porphyroblastic growth and differ in terms of the spatial extent of chemical equilibration and its influence on the distribution and compositional zoning of porphyroblasts. The first section of this chapter may serve as a review of some of the key works in metamorphic petrology addressing the factors that control the abundance and size distribution of porphyroblasts and their chemical zoning patterns.During retrograde stages of metamorphism or during metamorphic overprint of a previously largely dehydrated rock, crystallization may take place in a relatively 'dry' environment, where inter-crystalline diffusion is comparatively sluggish. In such a situation, reaction microstructures such as 'reaction bands' or 'corona structures' may develop. Typically, both the reactant and product phases are present providing evidence of incomplete reaction and indicating an overall disequilibrium situation. Chemical equilibrium may be restricted to microscopic domains along the phase boundaries or may not be attained at all. Nevertheless, important rate and time information may be obtained from the analysis of such reaction microstructures, if the processes underlying their formation are known and their rates are calibrated. The formation mechanisms of reaction bands and corona microstructures are discussed in the second section of this chapter.Finally, the mechanisms underlying symplectite formation, another phenomenon that is typically associated with metamorphic overprint of magmatic or metamorphic rocks, will be addressed in the third section of this chapter. Symplectites are spatially highly organized, fine-grained intergrowths of two or more different phases, replacing a more coarser-grained precursor phase at a sharp reaction interface. Symplectite microstructures are characterized by a specific length scale of phase alternation, by specific lamellar or rod-shaped microstructure and compositional patterns. In this chapter different avenues for extracting petrogenetic information from symplectite microstructures are discussed.

Natural nanoparticles are fundamental building blocks of Earth's bio- and geosphere. Amorphous silica nanoparticles are ubiquitous in nature, but fundamental knowledge of their interaction mechanisms and role in mineral replacement reactions is limited. Here we show how silica nanoparticles replace Cretaceous calcite bivalve shells in a volume-and texture-preserving process. Electron tomography reveals that mineral replacement transfers calcite crystallographic orientations to twinned photonic crystals composed of face-centered cubic silica sphere stacks. During the face-specific replacement process, silica nanoparticles continuously nucleate, aggregate, and form a lattice of uniform spheres parallel to calcite low-energy facets. We explain the replacement process with a new model that unifies recently proposed, probably universal mechanisms of interface-coupled dissolution-precipitation and aggregation-based crystallization; both key mechanisms in geological processes and nanomaterials design and synthesis.

Mineral coronas and reaction rims are frequent features in manymetamorphic rocks commonly interpreted as having been controlled by solid-state diffusion or by diffusion in an undefined medium. In material science the term 'interlayer growth' is often used for such processes. However, the terms 'reaction bands', 'corona structures', or 'rim structures' are commonly used as descriptive terms in petrology and we will use these below.The formation of reaction bands, coronas and reaction rims between incompatible phases requires that one or more chemical components are mobile. Knowledge of the transport mechanism and relative mobility of the distinct chemical components is of prime interest for the interpretation of reaction band sequences, growth rates, and subsequently forming fabrics and textures. Recent experimentation at high pressures and temperatures has shown that even minute traces of water are decisive in changing reaction mechanisms in silicate systems. In this chapter we present avenues of experimentation classified as water-rich, water-poor and water-absent. All of them are important in order to gain deeper understanding of mineral-reaction kinetics in the Earth in different environments, and of the formation of texture and zoning patterns in rock assemblages of the Earth or Earth-like planets.Experimental simulation and parameterization of variables relevant for mineral-reaction kinetics and the development of microstructures and textures requires a specific experimental approach. This consists of (1) application of time (or temperature) series; (2) miniaturization of experimental setups; and (3) experiments with perfectly defined geometries of the phases involved. This chapter specifies experimental setups for investigating mineral-reaction kinetics at high P-T, including setups for time-resolved, real-time monitoring of mineral nucleation and growth between incompatible phases at high T. We address mainly the experimental strategies in elucidating the controls of mineral-reaction kinetics rather than responding to results of particular studies, which can be found in many other chapters in this volume and in previous review articles (e.g. Dohmen and Milke, 2010; Watson and Dohmen, 2010). This holds also for the applied analytical methods as many experimental setups are specifically designed for subsequent analytical procedures.