A brief history of the nature, use and technology of binders in ancient constructions and buildings is outlined, including the apparent chronological discontinuities related to technological developments. The skilled and clever use of mineral resources is at the base of the technical achievements related to architectural activities, from simple adobe to high-performance modern concrete. It is argued that among pre-industrial binders the Roman pozzolanicmortars were highly optimized materials, skillfully prepared and very durable. Their innovative use in architecture is one of the keys of the successful expansion of the Roman Empire. The role of mineralogy and mineral reactions is emphasized in terms of: (1) the preparation and manufacturing of the binding materials; (2) the hardening process and the development of the physical properties of the binder; and (3) the archaeometric reconstruction of the ancient materials.
Copper was the first metal to have been smelted (extracted from its ore) some seven thousands year ago in the ancient Near East. For most pre-industrial periods, the documentation of copper smelting chaine operatoire relies mainly on investigations by archaeometallurgists of the metallurgical waste recovered during archaeological excavations, namely the copper slags. Copper slags are mostly an assemblage of crystals of oxides (iron, manganese, etc.), olivine (fayalite, etc.) and/or pyroxenes embedded in a polymetallic more-or-less glassy matrix. The mineralogy of the slags is directly related to the initial charge and the working conditions prevailing in the pyrometallurgical reactor. This chapter aims to give an overview of how copper slag mineralogy is investigated and the type of information it yields in order to help our understanding of past metallurgies and societies.
Fourier-transform infrared (FTIR) spectroscopy is a widespread and highly sensitive analytical method for the identification and characterization of a wide range of materials via their infrared (IR) absorption bands. Until now, the potential of IR microspectroscopy and imaging for the characterization of works of art or other objects of cultural heritage significance has been only partially exploited; in particular the use of the synchrotron radiation (SR) IR microprobe to study, at the micron scale, materials of interest for archaeological and cultural heritage studies has become popular only in the past decade. One of the main requirements imposed on the studies of ancient and/or valuable materials is that the techniques applied must be non-destructive. In this scenario, SR-based FTIR methods are perfectly suitable. Moreover, IR spectroscopy and imaging are emerging techniques that combine the assets of IR in terms of molecular specificity with the unique properties of synchrotron light. SR-FTIR micro-spectroscopy offers great advantages over conventional methods because it provides a broader spectrum (down to THz) and higher spectral quality (signal/noise ratio) at the highest spatial resolution (diffraction limited). This is due to the high brilliance and collimation of SR-IR, while still being non-damaging to the investigated system. The unique SR-IR parameters are essential for the compositional analysis of the tiny, sub-millimetric samples characteristic of ancient materials, which are heterogeneous by nature, and with complex molecular distributions at extremely variable concentrations. SR-FTIR spectroscopy and imaging can be applied successfully to the characterization of organic and inorganicmaterials via so-called IR fingerprinting, as well as for their compositional quantification. The range of materials investigated is very broad and encompasses painting materials, stones, glasses, ceramics, coatings on metals, paper and wooden materials, canvas or other textiles, organic colourants, resins, varnishes, cosmetics, and binding media such as glues, waxes, oils, etc. SR-IR-based methods can also be used to understand the historical technologies and to identify the raw materials used to produce archaeological artefacts and art objects, and to improve stabilization, conservation and restoration practices. Selected applications of SR-FTIR methods are discussed with a special emphasis on the chemical and mineralogical characterization of ancient paintings, on the study of alteration and corrosion layers, and the separation and identification of pigments. New perspectives offered by existing facilities and new developments in IR imaging and advanced vibrational spectroscopy that may broaden the variety of archaeological and historical materials that may be studied are outlined.
Over recent decades, numerous studies have highlighted the importance of opal, chalcedony and quartz varieties, chiefly in volcanic, but also in metamorphic and sedimentary environments. The focus is to define accurately their structures, composition and properties, as well as to identify the factors controlling the formation and the ageing of different forms of silica. In the field of archaeological sciences efficient discriminants are the bases from which the origin and provenance of materials may be traced. Substantial efforts were made in the attempt to combine geochemical, mineralogical, petrographic and geological features with archaeological and archaeometric information. However the results show that data integration is complicated, and several unanswered questions remain. On the one hand, archaeological research has focused on technological and ethnographic aspects, mainly concerning use-wear and heat-treatment studies. Mineralogical characterization has often been limited to the identification of the material, frequently by Raman microspectroscopy alone. On the other hand, the Earth sciences have provided basic mineralogical, crystal-chemical and geological knowledge, but failed to provide a systematic data collection of sources and their geochemistry. As a consequence, large gaps persist in the identification of archaeological opals, chalcedonies and quartz varieties, and in the geographic mapping of possible sources. In this context, the present review aims to summarize the current academic debate on such issues, possibly to encourage further work in the field. After a brief introduction to terminology, the structure of opals, their colours and properties are discussed, followed by an introduction to silica dissolution/precipitation and opal-formation processes. The next section reviews the information available on use of opals and provenance from historical sources, mainly Pliny the Elder, followed by a short list of ancient and modern opal supply areas, together with a (necessarily incomplete) summary of the geological and geochemical information. The discussion then encompasses chalcedony, agate and chalcedony varieties (carnelian, sard, onyx, sardonyx, chrysoprase, Cr-chalcedony, ‘gem silica’ or ‘chrysocolla chalcedony’ and heliotrope), following the same scheme as was adopted for opals. Terminology, distinguishing features, formation conditions, information derived from Pliny’s books, past and current supply areas and, finally, archaeometric provenance issues are addressed for each type of material. As for chalcedony, a comprehensive note on moganite has been included. The next section focuses on chert, flint and jasper. Given the large amount of materials available on this topic, the present review must necessarily be considered introductory and partial. The discussion aims to provide useful indications on how to distinguish chert from flint and chert from jasper; secondly, the information provided by Pliny and the archaeometric state of the art on these materials is reviewed. The last section examines quartz varieties: hyaline quartz (rock crystal), milky quartz, smoky quartz, rose and pink quartz, amethyst, citrine, prasiolite and blue quartz. An exhaustive mineralogical discussion on quartz is beyond the scope of this review; conversely a review of the historical information is provided, together with a brief list of major supply areas, a summary of the archaeometric studies performed on these materials, as well as an indication of the geological literature which can be used proficiently for provenance studies.
The Romans, like the Egyptians and much more than the Greeks, used polychrome stones for decorative purposes in architectural elements, floor and wall facings and statuary. Throughout their Mediterranean provinces they systematically searched for and exploited a very large number of beautiful lithotypes, many of which they distributed to all corners of their empire. The most important of these stones were often re-used later in medieval-to-modern times; some of them are still offered on the market. They include granitoid rocks (granites, granodiorites/tonalities, gabbros, quartz-monzonites), a few lavas, many metamorphites (impure marbles, metabreccias and metandesites) and several sedimentary rocks (limestones, lumachellas, conglomerates, calcareous alabasters/travertines). The 40 most important and widespread of these lithotypes are considered here as regards their origin, the history of their use and their minero-petrographic characteristics, which can contribute to better knowledge of single species, to determination of the original quarries and to archaeometric solutions of several provenance problems.
This short introduction aims to rethink the role of modern mineralogy and highlights the diverse and important contributions that it may provide in the study of materials and processes relevant to cultural heritage. It is argued that mineralogy lies in a very special position between Earth and materials sciences and that mineralogists have a profound perception of the structural and chemical complexity of natural materials. They possess knowledge of both the ancient and recent geological and physicochemical processes which produced the raw materials used by humans, and of the analogue processes used to transform them into artefacts. It is thus highly appropriate that a volume in the EMU series acknowledges some of the recent contributions of mineralogy to the investigation of human history, art and technology.
Early vitreous materials include homogeneous glass, glassy faience, faience and glazed stones. These materials evolved slowly into more specialized substances such as enamels, engobes, lustres, or even modern metallic glass. The nature and properties of vitreous materials are summarized briefly, with an eye to the historical evolution of glass production in the Mediterranean world. Focus is on the evolution of European, Egyptian, and Near East materials. Notes on Chinese and Indian glass are reported for comparison. The most common techniques of mineralogical and chemical characterization of vitreous materials are described, highlighting the information derived for the purposes of archaeometric analysis and conservation.
This contribution is dedicated to the memory of Professor Ursula Martius Franklin, a true pioneer of archaeometric research, who passed away at her home in Toronto on July 22, 2016, at the age of 94. Making ceramics by firing of clay is essentially a reversal of the natural weathering process of rocks. Millennia ago, potters invented simple pyrotechnologies to recombine the chemical compounds once separated by weathering in order to obtain what is more or less a rock-like product shaped and decorated according to need and preference. Whereas Nature reconsolidates clays by long-term diagenetic or metamorphic transformation processes, potters exploit a ‘short-cut’ of these processes that affects the state of equilibrium of the system being transformed thermally. This ‘short-cut’ is thought to be akin to the development of mineral-reaction textures resulting from disequilibria established during rapidly heated pyrometamorphic events (Grapes, 2006) involving contact aureoles or reactions with xenoliths. In contrast to most naturally consolidated clays, the solidified rock-like ceramic material inherits non-equilibrium and statistical states best described as ‘frozen-in’. The more or less high temperatures applied to clays during ceramic firing result in a distinct state of sintering that is dependent on the firing temperature, the duration of firing, the firing atmosphere, and the composition and grain-size distribution of the clay. Hence, the salient properties of the ceramics have to be assessed in a temperature-time-composition space. Owing to the variability of clay composition, the mineralogical processes during thermal transformation of clay minerals can be very complex, not least because most reactions occur far removed from thermodynamic equilibrium and hence are kinetically controlled; that is, they are time- and temperature-dependent. Indeed, kinetics imposes constraints on thermodynamics by retarding reaction rates because of low temperatures, large temperature gradients present in primitive pottery kilns, short reaction times, inhomogeneously distributed reaction partners, and varying redox conditions triggered, for example, by ingress of air during reducing firing cycles. In the context of ceramic technological development over time, the role and development of pottery technology within complex societies is discussed. The close relationship between pottery development and changes in life/societal organization appears to be a major driver in this endeavour. In this chapter, the phase evolution of some typical ancient and historical ceramics will be traced using ceramic phase diagrams, i.e. chemographical expressions of Goldschmidt’s mineralogical phase rule. In particular, the systems CaO–Al2O3–SiO2 (in which most ancient low- to medium-fired ceramics can be accommodated), K2O–Al2O3–SiO2 (applicable to high-fired Chinese stoneware and European hard-paste porcelain) and Na2O–CaO–(Al2O3)–SiO2 (typical of some ancient Egyptian and Mesopotamian alkaline glazes and French soft-paste porcelain) are discussed.
The use of minerals as pigments in art and on archaeological objects, from the use of ochre in prehistoric caves to the elaborate transformation and use in ancient and modern artist palettes, is reviewed in this chapter. Starting from the purposes of the study of pigments, the chapter presents current trends in the study of coloured minerals in cultural heritage science. It emphasizes through the use of case studies the potential of these minerals in terms of information about former ways of life and especially the artistic techniques employed in ancient times. This information is gained through knowledge of geological and physicochemical processes acting on minerals and on artefacts produced by human activities. Some new trends are presented as the state of the art of how to master most of the methods and techniques useful for investigating our common cultural heritage.
Archaeometric studies of ancient artifacts containing gems or gem-quality geological materials have an intrinsic complexity. The scientific questions to be answered are related not only to the type of material used (e.g. a mineral or poly-mineral geological material), but also to their age and provenance. The answers can derive only from multidisciplinary study which combines experimental observations with information and clues from different disciplines. This paper presents three case studies in which mineralogical knowledge and the noninvasive approach typical of gemmological analyses solve the problem of gem identification. The answer aboout the origin of gems and/or minerals is more complex because little is known about the chaîne opératoire that precedes the use of gems in artifacts. Little is known currently about the geological complexity of ancient ores, some are now exhausted. Moreover, the criteria used in choosing raw material are not known. A multidisciplinary approach can lead to identification of the sources of supply of the material, understanding the choices made for the realization of the artifacts, defining the links with the geological, geographical and cultural realities that complete their context of origin. Correct archaeometric investigation must follow the ‘four C’s’ rule and keep in mind the ‘complexity’ of the artifact, answer ‘congruent’ questions to the study, aggregate different ‘competences’ and be open to ‘collaborations’.
Obsidian is a volcanic product that forms under particular geological conditions, and hence occurs in limited areas of the Earth. In ancient times, obsidian was used successfully by various peoples to produce artistic artefacts, but also to make tools and weapons used in everyday life. For this reason, obsidian was transported from geological sources to other locations. The study of methods used to identify the provenance of obsidian artefacts has become crucial for understanding commercial relations between distant ancient populations. Other volcanic products, generally associated with obsidian, are volcanic glass shards. Glass shards were used in Mexico as aggregates to produce plasters, and recent studies have shown that they were also transported along commercial routes. This chapter presents an introductory overview of the sources of obsidian in the Tyrrhenian area, showing how minor, trace and rare earth elements can be used to solve provenance problems. A case study regarding the provenance of glass shards inside archaeological plasters taken from Teopacazco (Teotihuacan, Mexico) is also presented.
From shell beads in the Palaeolithic and stone beads in the Neolithic to beautiful artificial gems in modern times, the history of gems has roughly paralleled that of humans. In the beginning, myths and folklore about the healing properties of gemstones dominated the story. Today, the story is about scientific techniques making larger or more colourful gems and newly discovered mineral deposits revealing gemstone treasures. In the western world the written history of precious and semiprecious stones begins with the On Stones of the Greek philosopher and naturalist Theophrastus (ca. 315 BC) followed by the Natural History of the Roman historian Pliny (77 AD), which was the standard work on gems and minerals for more than a thousand years. The gemstones of the Old Testament and those of ancient East Asia tell their separate stories. Following a brief summary of these early works, this paper continues with individual descriptions of the major gems and semiprecious stones, focusing on their two most important attributes - colour and hardness - as well as where they are found. This is followed by a brief discussion of altered gems and a summary of modern interactions of gems and man. This paper concludes with some personal experiences of the author and a brief introduction to the geology of gem deposits.
The crystal structures and chemical compositions of sulfide minerals are summarized briefly before going on to review their redox chemistries, particularly the roles played by bacteria. In the formation of sulfide minerals, two processes need to be considered; one applicable to all sulfide systems is the microbial reduction of sulfate, the other is microbial reduction of metals, especially iron. Sulfate-reducing prokaryotes (SRP) can supply reactive sulfide ions for the formation of sulfide minerals. The SRP, of which there are more than 120 species, are ubiquitous in many anaerobic environments, although marine sediments are the most important. The SRP are able to grow under extreme conditions of pH and temperature. Bacteria can also conserve energy by reducing metals, such as reduction of Fe(III) coupled to the oxidation of organic matter. Biological processes also mediate the dissolution of sulfides under acid mine drainage conditions, and there are a diversity of acidophilic (pH <3) metal sulfide-oxidizing microorganisms. The oxidation reactions of pyrite, galena, arsenopyrite and chalcopyrite are discussed in detail before considering how toxic metals may be bound to the surfaces of sulfides such as pyrite and mackinawite. The applications of sulfide bacterial redox processes in clean technologies, such as bioleaching and biomining, are discussed briefly.
Water pollution is a major global problem at present, involving inorganic and organic contaminants such as heavy metals, pesticides and pharmaceutical compounds, as well as pathogens. Therefore, the development of water-management strategies and appropriate water-treatment technologies has been the subject of intense research for decades. This chapter reviews the potential use of redox-reactive minerals as reactive media in environmental cleanup technologies especially in the removal of arsenic, nitrate, persistent organic pollutants and pathogenic microbes. The properties and applications of five classes of redox-reactive materials are summarized: zero-valent metals, mixed-valence iron oxyhydroxides, Fe-bearing clays, mixed-valence manganese oxides and titanium and zinc oxides. Examples and case studies that demonstrate the significant role of these reactive materials in water-treatment processes are also provided.
Undercooling and crystallization kinetics are recognized increasingly as important processes controlling the final textures and compositions of minerals as well as the physicochemical state of magmas during ascent and emplacement. Within a single volcanic unit, phenocrysts, microphenocrysts and microlites can span a wide range of compositions, develop complex zoning patterns, and show intricate textures testifying to crystallization far from equilibrium. These petrographic complexities are not associated necessarily with magma chamber processes such as mixing or mingling of distinctly different bulk compositions but, rather, may be caused by variable degrees of initial magma-undercooling and the evolution of undercooling through time. Heat-dissipation and decompression are the most effective driving forces of cooling and volatile loss that, in turn, exert a primary control on the solidification path of magma. Understanding these kinetic aspects over the temporal and spatial scales at which volcanic processes occur is therefore essential to interpret correctly the time-varying environmental conditions recorded in igneous minerals. This contribution aims to summarize and integrate experimental studies pertaining to the crystallization of magmas along kinetic or time-dependent pathways, where solidification is driven by changes in temperature, pressure and volatile concentration. Fundamental concepts examined in the last decades include the effect of undercooling on crystal nucleation and growth as well as on the transition between interface-and diffusion-controlled crystal growth and mass transfer occurring after crystals stop growing. We summarize recent static and dynamic decompression and cooling experiments that explore the role of undercooling in syn-eruptive crystallization occurring as magmas ascend in volcanic conduits and are emplaced at the surface. The ultimate aim of such studies is to decode the textural and compositional information within crystalline phases to place quantitative constraints on the crustal transport, ascent and emplacement histories of erupted and intrusive magmas. Magma crystallization under dynamic conditions will be assessed also through a comparative description of the disequilibrium features in minerals found in experimental and natural materials. A variety of departures from polyhedral growth, including morphologies indicating crystal surface instability, dendritic structures, sector zoning and growth twins are linked to the rate at which crystals grow. These have implications for the entrapment of melt inclusions and plausibility for interpreting the growth chronology of individual crystals. A simple "tree-ring'' model, in which the oldest part of the crystal lies at the centre and the youngest at the rim, is not an appropriate description when growth is non-concentric. Further, deviation from chemical equilibrium develops in response to kinetically controlled cation redistributions related to the partitioning of major and trace elements between rapidly growing crystal and melt. The incorporation into the crystal lattice of chemical components in non-stoichiometric or non-equilibrium proportions has important implications for the successful interpretation of the conditions under which magmas crystallize and for the development of new equilibrium models based on mineral compositional changes. Finally, it is important to stress that the main purpose of this contribution is to ignite research exploring the causes and consequences of cooling and decompression-driven crystal growth kinetics in order to appreciate in full the evolutionary paths of volcanic rocks and interpret the textural and compositional characteristics of their mineral constituents.
For the safe disposal of nuclear waste, the ability to predict the changes in oxidation states of redox active actinide elements and fission products, such as U, Pu, Tc and Np is a key factor in determining their long term mobility. Both in the Geological Disposal Facility (GDF) near-field and in the far-field subsurface environment, the oxidation states of radionuclides are closely tied to changes in the redox condition of other elements such as iron. Iron pervades all aspects of the waste-package environment, from the steel in the waste containers, through corrosion products, to the iron minerals present in the host rock. Over the long period required for nuclear waste disposal, the chemical conditions of the subsurface waste package will vary along the entire continuum from oxidizing to reducing conditions. This variability leads to the expectation that redox-active components such as Fe oxides can undergo phase transformations or dissolution; to understand and quantify such a system with respect to potential impacts on waste package integrity and radionuclide fate is clearly a serious challenge. Traditional GDF performance assessment models currently rely upon surface adsorption or single-phase solubility experiments and do not deal with the incorporation of radionuclides into specific crystallographic sites within the evolving Fe phases. In this chapter, we focus on the iron-bearing phases that are likely to be present in both the near and far-field of a GDF, examining their potential for redox activity and interaction with radionuclides. To support this, thermodynamic and molecular modelling is particularly important in predicting radionuclide behaviour in the presence of Fe-phases. Examination of radionuclide contamination of the natural environment provides further evidence of the importance of Fe-phases in far-field processes; these can be augmented by experimental and analogue studies.
Crystallographic orientation relationships (CORs) of next-neighbour crystals represent a special case of crystallographic preferred orientation (CPO), where relative crystallographic orientations of neighbour-crystals follow defined rules of misorientation systematics (COR rules). The presence/absence and nature of crystallographic orientation relationships between next-neighbour crystals can be used to infer petrogenetic information from polycrystalline materials provided that the processes of COR formation are understood and parameters that control the kinetics of COR formation can be identified. After giving an overview on COR terminology, this chapter highlights non-genetic criteria for COR characterization, including a discussion of analytical methods that are used to constrain these criteria. The development of electron backscatter diffraction (EBSD) in scanning electron microscopy (SEM) has provided new information on CORs, which is complementary to data obtained from transmission electron microscopy (TEM) analysis. Based on these non-genetic criteria, different types of CORs are characterized. Subsequently, physical parameters that can potentially influence COR formation are discussed. Furthermore, different scenarios and mechanisms leading to COR formation are outlined together with examples from experiments and from natural mineral and rock systems. The different boundary conditions of COR formation in various petrogenetic scenarios and the potential mechanisms that have to be taken into account when studying COR genesis are addressed. This chapter highlights the necessity of a multi-stage investigative approach in COR studies. First, the presence/absence and nature of CORs needs to be analysed based on non-genetic criteria. In a second step the formation mechanism of the CORs under consideration must be constrained, before in a third step, petrogenetic information can potentially be inferred. Moving from the second to the third step requires understanding of the parameters controlling COR development, which is by no means complete and leaves open tasks for future COR research.
Scanning electron microscopy (SEM) is one of the most frequently used techniques for near-surface characterization of most solid (and some liquid or liquid-containing) materials with a lateral resolution ranging between 1 nm (for surface-morphology observations) and 1 mm (for certain elemental-composition measurements). It works by scanning a finely focused electron beam over a surface and recording a variety of signals obtained from the electron-beam illuminated volume. Besides observation of the morphology of the surface of materials by recording of secondary electrons, SEM allows the measurement of elemental composition (e.g. by X-ray spectroscopy) and crystallographic nature (by backscattered electrons) of microscopic volumes beneath the surface. Even information on the chemical bonding (by Auger electrons) and on the electronic state (e.g. by cathodoluminescence) of microscopically small-volume elements can be obtained. Furthermore, direct observation of crystal lattice defects is possible. Many of the observations and measurements can be performed simultaneously, thus referring to the same position on a sample surface. Furthermore, materials may be modified during the measurements, e.g. by heating or mechanical loading, and changes can be observed either in situ or by means of interrupted tests. Particularly powerful techniques for characterization of crystalline materials in SEM are electron backscatter diffraction (EBSD) and EBSD-based orientation microscopy. These techniques allow quantitative characterization of microstructures (i.e. defect arrangements) of bulk crystalline materials down to a lateral resolution of similar to 50 to 200 nm (depending on material and microscope conditions). The largely automated analysis of electron backscatter diffraction patterns (EBSPs) yields the crystallographic phase, orientation, defect density, and, potentially, elastic stress state of the illuminated crystal volume. Crystal orientation mapping (COM) is performed by scanning the electron beam over the sample and recording and analyzing a diffraction pattern from every point of the scan grid. The data obtained can then be plotted, for example, in the form of orientation, misorientation or phase maps of the scanned area. These maps reveal all kinds of morphological data such as grain size, grain shape, spatial distribution of phases and defects and much more. Besides this, the orientation data represent the texture of the investigated area. Together with EBSD scanning, further signals can be recorded, e.g. the elemental composition via energy-dispersive X-ray spectroscopy (EDX) or opto-electronic properties via cathodoluminescence (CL). This enhances the strength of the technique even further.
This chapter deals with the crystal structure of regulated and unregulated mineral fibres. The aim is to provide readers, both specialists and researchers broadly interested in environmental problems, with up-to-date information on a topic that is expanding daily. The chapter describes specifically the structure of the fibrous modification whenever available and outlines possible differences from the corresponding prismatic variety. Details of the experimental techniques used for structure determination/refinement are reported also, if appropriate, to outline the experimental difficulties faced due to the small dimensions, sensitivity and chemical complexity of mineral fibres.
