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Gemstones and noble metals adorning the sceptre of the Faculty of Science of Charles University in Prague: integrated analysis by Raman and XRF handheld instruments
Abstract
A commonly marketed handheld Raman spectrometer showed excellent possibilities in being used as a key instrument for unambiguous identification of gemstones mounted in the sceptre of the Faculty of Science of Charles University in Prague from the mid-20s of the 20th century. Numerous SiO2 forms including chalcedonies intermixed with moganites (e.g. moss agates and carnelians), amethysts, citrines as well as garnets (pyrope–almandines) were identified. The estimation of the garnet type was based on obtained Raman parameters. The individual minerals constituting the lapis lazulis could not be discerned because of very high fluorescence they exhibited in the fingerprint region of the Raman spectrum, nevertheless the positions of the observed peaks in the 1000–2000 cm–1 area were in very good agreement with the values of commercially available lapis lazuli pigment. The noble metals of the sceptre were studied by means of X-ray fluorescence analysis, which confirmed the presence of silver alloys and gilding. The comparison of silver alloys' semiquantitative analysis with the expected fineness, denoted by the hallmarks, indicated silvering. This has been later confirmed by the newly discovered restoration documentation. Portable handheld Raman and X-ray fluorescence instruments represent an ideal tool for studying historical artefacts, where an in situ investigation in museums or similar sites is obligatory. Copyright © 2012 John Wiley & Sons, Ltd.
... The use of non-invasive and non-destructive spectroscopic techni- ques, such as Fourier Transform Infrared Spectroscopy (FT-IR) and RAMAN, for the characterization of geomaterials of museum interest (ceramics, gemstones, metallic artefacts, bones, etc.) for which a con- servative treatment of the sample is required, is gaining more and more interest in applied mineralogy [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Demand by stakeholders ac- counts for reliable, fast and cheap information concerning the structural classification of gemstones (typology, defects, etc.) as well as prove- nance [18]. ...
... In a traditional Mid-Infrared spectroscopic analysis, most of the IR radiation absorptions by tourmalines are mainly due to stretching and bending vibrations in tetrahedral [T 6 O 18 ] and triangular [BO 3 ] 3 co- ordination structural sites, showing main absorption bands in the re- gion 1500 and 400 cm −1 . These absorption bands seem to be very useful for distinguishing natural tourmaline and respective imitations [4]. ...
Fourteen samples of tourmaline from the Real Museo Mineralogico of Federico II University (Naples) have been characterized through multi-methodological investigations (EMPA-WDS, SEM-EDS, LA-ICP-MS, and FT-IR spectroscopy). The samples show different size, morphology and color, and are often associated with other minerals. Data on major and minor elements allowed to identify and classify tourmalines as follows: elbaites, tsilaisite, schorl, dravites, uvites and rossmanite. Non-invasive, non-destructive FT-IR and in-situ analyses were carried out on the same samples to validate this chemically-based identification and classification. The results of this research show that a complete characterization of this mineral species, usually time-consuming and expensive, can be successfully achieved through non-destructive FT-IR technique, thus representing a reliable tool for a fast classification extremely useful to plan further analytical strategies, as well as to support gemological appraisals.
... specific gravity, refractive index, thermal conductivity) and microscopic characteristics [7,8]. However, spectroscopic research provides specific information about the (elemental or molecular) composition of the material and thus results in a more complete identification [9,10]. When applying analytical methods for the characterisation of museum artefactsin this particular case lithic materialit should be taken into account that some objects are immovable due to their size or preciousness. ...
... In the last decades, in-situ analysis of these precious materials, gained interest: several publications are found where in situ Raman or XRF spectroscopy is used for the identification of natural gems and imitations [10,[14][15][16][17][18]. Nowadays, also the complementary use of XRF and Raman spectroscopy for these types of samples turns to be an interesting topic. ...
In archaeometry, the advantages of a combined use of Raman spectroscopy and X-ray fluorescence spectroscopy are extensively discussed for applications such as the analysis of paintings, manuscripts, pottery, etc. Here, we demonstrate for the first time the advantage of using both techniques for analysing glyptics. These engraved gemstones or glass materials were originally used as stamps, to identify the owner, for instance on letters, but also on wine vessels. For this research, a set of 64 glyptics (42 Roman glass specimens and 22 modern ones), belonging to the collection of the museum 'Quinta das Cruzes' in Funchal (Madeira, Portugal), was analysed with portable Raman spectroscopy and handheld X-ray fluorescence (hXRF). These techniques were also used to confirm the gemological identification of these precious objects and can give extra information about the glass composition. Raman spectroscopy identifies the molecular composition as well as on the crystalline phases present. On the other hand, hXRF results show that the antique Roman glass samples are characterised with low Pb and Sn levels and that the modern specimens can be discriminated in two groups: lead-based and non-lead-based ones.
... As this set of gems is considered a priceless national treasure, such studies can only be conducted within the Museum, using classical nondestructive gemo-logical tools and mobile spectrometers. In the last two decades, several instruments useful for characterizing gems in situ have been developed in mobile versions, drawing the interest of researchers from various disciplines (Reiche et al., 2004;Petrová et al., 2012;Barone et al., 2016;Panczer et al., 2021;Karampelas and Wörle, 2022). ...
Forty-five “emeralds,” formerly set in the coronation crown of Napoleon III, were studied using nondestructive mobile spectroscopic and gemological means. Adorned with emeralds, diamonds, and gold, the crown was created in 1855 by royal jeweler Alexandre Gabriel Lemonnier but dismantled in 1887 for the auctioning of the French crown jewels. Some of the emeralds were donated to the École des Mines (Paris School of Mines, now known as Mines Paris - PSL) in 1887, prior to the auction. Our examination revealed that 41 out of 45 gems were indeed natural emeralds, presenting no evidence of clarity enhancement. Their gemological characteristics and age suggest a Colombian provenance. The other four samples were determined to be artificial glass containing iron and/or copper and possibly other chromophores. These glass imitations could have been set when the crown was created or shortly thereafter. This study is part of an effort to examine gemstones of historical meaning and significance worldwide.
... Noninvasive Raman analysis is carried out, among others, on illuminated manuscripts [83], wall paintings [84,85], glass [86,87], gems and gemstones [88] and mosaics [80,89]. Impressive work has been done in the case of measuring directly on rock art paintings [76,[90][91][92]. ...
Raman and infrared spectroscopy are two of the most frequently used molecular techniques in the fields of archaeometry and art analysis. Both techniques use advanced benchtop configurations for conducting laboratory investigations, but also can be applied on-site and/or directly on the artefact, and produce high-quality results. In this chapter, vibrational spectroscopy is discussed, giving a short introduction on its theory, followed by the description of approaches and instrumental advances for the two techniques.
... Carnelian gems have been used since antiquity [56,[60][61][62][63] and sources are rather well documented for the Mediterranean world [60] and for India [1,2,[32][33][34][35][36]. The moganite peak has not been reported previously. Traces of hematite (α-Fe 2 O 3 ) were evidenced with its characteristic ca. ...
In the late 19th century, ancient tombs were discovered near the village of Vohemar at the northeastern point of Madagascar, and subsequent excavations during the French period (1896–1945) revealed the presence of a major necropolis active from ~13th to 18th centuries. Some artefacts (Chinese ceramic shards and glass trade beads) recovered from these ex-cavations was sent to France and now in part belong to the collection of the Musée d’Histoire Naturelle, Nimes. Carnelian and glass trade beads were analyzed with a mobile Raman spectrometer, which identified different materials (soda-lime glass, quartz/moganite, carnel-ian/citrine, chalcedony) and coloring agents (Naples yellow, cassiterite, amber chromophore, transition metal ions, etc.). The results are compared with those obtained on beads excavated at different sites of Southern Africa and at Mayotte Island, and it appears that (most of) the beads come from southern Asia and Europe. The results confirmed the role that northern Madagascar played within the maritime networks of the Western Indian Ocean during the 15th–16th century.
... The development of portable XRF and Raman spectrometers has induced an increasing number of archaeometric studies focused on ancient goldsmith's items, as for example the Prague sceptre (Petrová et al., 2012), the Messina and Paolo Orsi jewellery collections (Barone et al., 2015(Barone et al., , 2016, and the reliquary-bust of Saint Lambert (Bruni et al., 2019). In this paper, we present the results of a Raman and pXRF study of the reliquary of Saint Simètre (Lierneux, Belgium), with a special attention on the glass beads decorating the surface of this item. ...
The reliquary of Saint Simètre (or Symètre), which is exposed in the Saint André church of Lierneux, was produced during the middle of the 13th century. It is made of a wooden chest with a roof (77 × 28 × 39 cm) covered by silver and golden copper, and decorated by 39 stones which were analysed by Raman and pXRF techniques to determine the nature of colouring agents and of raw materials. The results confirm the identification of 39 glass beads with green, blue, red or pink colours and showing a simple cutting. They show a lead silicate composition (45–55 wt% PbO) with a high level of potassium (5–10 wt% K2O), and iron, cobalt, manganese and/or copper as coloring agents. The silver samples contain 98 wt% of Ag, and the golden border contains approximately 85 wt% of Cu and 14 wt% of Au. The brass decorations on the roof shows an average of 68 wt% of Cu and of 29 wt% of Zn. This study confirms that lead glass beads are contemporary to the reliquary and imported from central Europe.
... Furthermore, analytical studies of jewellery, especially the ones with non-invasive on-site procedures are very limited and rather focused on the identification of 'gems' or their replacement by synthetic glass [46][47][48][49][50][51][52][53][54]. As a rare example, the enamelled jewellery of René Lalique from the 20 th century (Art Déco style) has recently been analysed by the combination of Raman spectroscopy and XRF which were although carried out at the laboratory [55]. ...
Twelve rare watches with painted enamels, mostly produced in France, from the 17 th and 18 th centuries in the collections of Musée du Louvre in Paris were analyzed on-site in order to characterize the materials used in their enamels and the enamelling technique. All the watches were analysed by mobile Raman microspectroscopy and five of them were also analyzed by pXRF. Pigments (Naples Yellow pyrochlore, hematite, carbon, lapis lazuli, arsenic sulphide, manganese oxides), opacifiers (cassiterite, lead arsenates) and corresponding lead-rich glassy silicate matrices were identified by one or two methods. Similar to the oil painting or tempera techniques, different hues of the related enamels were obtained by mixing many colouring agents, rather than using 'pure' enamels as in the case of Limoges enamelled objects. Lead arsenate apatite detected in some of the 17 th century blue enamels is related to the use of European arsenic-rich cobalt ores, as also characterized in the blue (soft-paste) porcelain decors and high-quality Limoges enamels. The presence of colloidal gold (Au° nanoparticles) was indirectly detected by the Raman technique in the 18 th century watches and confirmed by pXRF. At least three types of Naples Yellow pigment were identified with Sb-rich, Sn-rich and mixed Sb-Sn-Fe-Zn compositions.
... For XCT, provided the object is well-packed, the object can be examined with no direct interaction and the composition and structure of the object remains unaltered at the typically low X-ray energies used for most samples [23,48,49]. Chemical approaches are also typically non-invasive, macro-XRF typically utilising handheld non-contact scanners to acquire information, although micro-XRF may require samples to be taken, as in this paper, as they utilise lab-based, desktop equipment that has a limited chamber size [47,50,51]. EDX however will always require some minor destructive sampling, given the typically small size of the vacuum chamber utilised [47]. ...
This paper demonstrates the combined use of X-ray computed tomography (XCT), energy dispersive X-ray spectroscopy (EDX) and X-ray fuorescence (XRF) to evaluate the conservational history of the dentary (lower jaw) of Megalosaurus bucklandii Mantell, 1827, the first scientifcally described dinosaur. Previous analysis using XCT revealed that the specimen had undergone at least two phases of repair using two diferent kinds of plaster, although their composition remained undetermined. Additional chemical analysis using EDX and XRF has allowed the determination of the composition of these unidentifed plasters, revealing that they are of similar composition, composed dominantly of ‘plaster of Paris’ mixed with quartz sand and calcite, potentially from the matrix material of the Stonesfeld Slate, with the trace presence of chlorine. One of the plasters unusually contains the pigment minium (naturally occurring lead tetroxide; Pb2 2+Pb4+O4) whilst the other seems to have an additional coating of barium hydroxide
Ba(OH)2), indicating that these likely represent two separate stages of repair. The potential of this combined approach for evaluating problematic museum objects for conservation is further discussed as is its usage in cultural heritage today.
... Raman spectroscopy is now routinely used as a primary or screening method in gemmology, and for studying gemstones mounted in historical objects under laboratory conditions (golden chalices from the Einsiedeln Abbey, Switzerland, crafted in the seventeenth century [19] and the Reliquary Cross and Dorothy Monstrance from Basle Cathedral, Switzerland, of the late Gothic period [20]) or even in situ (Heinrich's Cross from Basle Cathedral dating from the late Middle Ages [21], the sceptre of the Faculty of Science of Charles University, Prague, Czech Republic [22] and the silver Torah shield [23], Prague) without the necessity to move or remove the artefacts. Recently, Raman microspectroscopy was used for characterization of emeralds [24] and rubies and their imitations [25]. ...
A miniature lightweight portable Raman spectrometer and a palm-sized device allow for fast and unambiguous detection of common gemstones mounted in complex jewels. Here, complex religious artefacts and the Ring Monstrance from the Loreto treasury (Prague, Czech Republic; eighteenth century) were investigated. These discriminations are based on the very good correspondence of the wavenumbers of the strongest Raman bands of the minerals. Very short laser illumination times and efficient collection of scattered light were sufficient to obtain strong diagnostic Raman signals. The following minerals were documented: quartz and its varieties, beryl varieties (emerald), corundum varieties (sapphire), garnets (almandine, grossular), diamond as well as aragonite in pearls. Miniature Raman spectrometers can be recommended for common gemmological work as well as for mineralogical investigations of jewels and cultural heritage objects whenever the antiquities cannot be transported to a laboratory.
This article is part of the themed issue ‘Raman spectroscopy in art and archaeology’.
... In this context, in particular, the combined use of XRF and Raman spectroscopies represents a successful approach for a non-invasive study that allows for complementary compositional information, the first one at elemental level, the second one on molecular scale. It has been already applied in a variety of findings including potteries 11 , frescoes 12 , glasses 13 , gemstones 14 and paintings 15 . In fact, the elemental (qualitative and/or semi-quantitative) analysis performed by XRF becomes necessary for the unambiguous phase identification of both organic and inorganic materials by Raman technique, and vice versa. ...
In the present work, a variety of fragments of frescoes coming from the Villa dei Quintili in Rome (Italy) and dating back to the II century A.D. were subjected to, first of all, an X-ray fluorescence (XRF) analysis by optimizing a portable spectrometer for non-destructive investigation in the field of cultural heritage. The innovative aspect is the ability to obtain coloured maps referring to the distribution and concentration of elements present in the sample. Other than characterization, the aim was to improve the technique for non-invasive and fast in situ analysis. It has been performed, in conjunction with portable Raman analysis, at the ruins of the Villa dei Quintili on samples of different typologies including pottery, statues and frescoes, dating back to the II/III century A.D., different in colour, support and shape. From the results, the identification of the main pigmenting agents is attempted, providing the group of archaeologists in the villa with extremely valuable information for their work too. In particular, by comparing the XRF results for frescoes analysed in the laboratory, taken from the warehouse of the villa, and XRF and Raman data of frescoes analysed in situ, for which the provenance area inside the villa was known, the context of excavation and the manufacture process for some of the former has been hypothesized.
... Their refraction index is 1.54, specific gravity is 2.63, and UV fluorescence (365 nm) is none to very weak blue, which is in agreement with the published data for chrysoprase (Shigley et al. 2009). The Chelsea filter reaction [which is used for the detection of chromium in the sample either as artificial colourant or as a rare natural colouring agent in chrome chalcedony (Petrová et al. 2012;Hyršl 1999)] was green, Fig. 8 XRD patterns of Szklary chrysoprase and "kerolite"/"pimelite" sample. The dashed line indicates the main diffraction line of "kerolite"/"pimelite". ...
Green clay and chrysoprase samples from the Ni-laterite deposit in Szklary, Poland, were studied by X-ray diffraction (XRD), electron microprobe analysis (EMPA), Raman, infrared and UV–VIS–NIR absorption spectroscopies. The clay samples proved to be Ni-rich “kerolite” and “pimelite”, and as these minerals are currently discredited, their nature was studied in more detail by high-temperature X-ray diffraction and thermal analysis coupled with mass spectrometry. These methods showed that “kerolite” and “pimelite” contain interlayer water, i.e. they differ from the non-hydrated talc–willemseite mineral series. Subsequently, the XRD and EMPA analyses of Szklary chrysoprase indicated that chrysoprase’s colouring agent is “pimelite”, which was further corroborated by Raman and UV–VIS–NIR spectroscopies. In addition, the Szklary chrysoprase, which has been quarried since the Middle Ages and used in jewellery and wall decorations (e.g. in the Prague Cathedral), was described from the gemmological point of view.
... Such provenance studies by Raman spectroscopy are also relevant to other fields like, for example, the earth sciences [9]. The current wide availability of portable instruments benefits gemmology and the cultural heritage by enabling in situ measurements of precious objects, which generally require on-site analysis and often have barely accessible areas to measure [14,237]. ...
Rooted in the long tradition of Raman spectroscopy of cultural heritage materials, in this work we provide a personal perspective on recent applications and new frontiers in sampling modalities, data processing, and instrumentation.
... However, the obtained results (Figs. 2–4 and Table 4) were largely influenced by fluorescence. This effect is commonly encountered; several authors have experienced it especially when using 785 nm laser on different materials of blue or green colour [20] [21] – having that in mind, we performed the analysis using the 532 nm laser. We have tested the Raman measurements on selected samples containing verdigris-type pigment, Cu sulphates and Cu chlorides. ...
An unambiguous identification of pigments in paint layers of works of art forms a substantial part of the description of a painting technique, which is essential for the evaluation of the work of art including determination of the period and/or region of its creation as well as its attribution to a workshop or an author. Copper pigments represent a significant group of materials used in historic paintings. Because of their substantial diversity and, on the other hand, similarity, their identification and differentiation is a challenging task. An analytical procedure for unambiguous determination of both mineral-type (azurite, malachite, posnjakite, atacamite, etc.) and verdigris-type (copper acetates) copper pigments in the paint layers is presented, including light microscopy under VIS and UV light, electron microscopy with elemental microanalysis, Fourier transformed infrared micro-spectroscopy (micro-FTIR), and X-ray powder micro-diffraction (micro-XRD). Micro-Raman measurements were largely hindered by fluorescence. The choice of the analytical methods meets the contemporary requirement of a detailed description of various components in heterogeneous and minute samples of paint layers without their destruction. It is beneficial to use the combination of phase sensitive methods such as micro-FTIR and micro-XRD, because it allows the identification of both mineral-type and verdigris-type copper pigments in one paint layer. In addition, preliminary results concerning the study of the loss of crystallinity of verdigris-type pigments in proteinaceous binding media and the effect of lead white and lead tin yellow as highly absorbing matrix on verdigris identification in paint layers are reported.
A comprehensive survey is made of the various types of mobile Raman spectroscopic instrumentation that is available for in- field and on site analysis and an evaluation is made of the spectral data that are given from their usage. The reasons for on-site analysis are explored against the taking of specimens for analysis in the laboratory.The role of different parts of the instrumentation is reviewedand the need to protect from ambient light. Stand-off Raman spectroscopy. Finally, examples are given of case studies of the use of this instrumentation in the field and on-site in museums.KeywordsPortable Raman spectroscopyInstrumentationIn field usageOn-site usage in museumsStand-off Raman spectroscopy
The role of Raman spectroscopic studies in identifying natural and synthetic gemstones is comprehensively evaluated. Input to provenance studies and correlation of spectral data with combined techniques. Distinguishing gems from glass and the detection of fakes and results from the improvement of the quality of gemstones by artificial methods. Case studies of jade, corals, pearls, ivory and ambers. Development of onsite interrogation of jewelled reliquaries and monstrances.KeywordsNatural gemstones Synthetic gemstones Fakes Modified and synthetic gemstones JadeCoralAmberIvoryReliquariesMonstrances
This review focuses on the progress made and recent developments regarding the use of portable Raman spectrometric devices in the geosciences as well as with scientific testing of objects of cultural heritage. By utilizing different types of Raman spectrometric devices - from the modular; through systems operating with optical heads mounted via optical fibers; to the compact, lightweight, and handheld - are herein described and critically evaluated. The wide range of applications under indoor and closed environments (museums, collections, religious buildings, etc.) are reviewed, and the more commonly used for characterization of art in the broadest sense, as well as fully outdoor investigations (e.g., on rocky outcrops; of the minerals, microbiological colonization, etc.), and including extreme Earth environments and projects with exo-planetary research potential. The rapid acquisition of relevant spectroscopic data and the non-destructiveness of the analyses and diagnostics are greatly appreciated by art historians and conservators on the one hand, as well as by mineralogists, geoscientists, microbiologists on the other. The various environments investigated and the broad range of compounds that can be detected by obtaining their Raman spectra have demonstrated the vast potential of portable, and especially handheld, Raman spectrometer devices for on-site applications.
Nineteen green‐coloured gems adorning a cross‐shaped pendant from the end of 19th century, belonging to Einsiedeln Abbey (Switzerland), were examined using non‐destructive methods. Estimated weights of the gems are ranging from about 0.19 to 2.34 carats. Natural multiphase inclusions with jagged outlines were observed in all samples under optical microscope. Raman bands characteristic of beryl were observed in all samples with a 532‐nm laser excitation. Raman spectra of the samples with a 785‐nm laser at higher wavenumber found to be similar to emeralds containing low concentration of alkali elements. Their ultraviolet–visible–near‐infrared (UV–Vis–NIR) spectra display absorption bands related to chromium and vanadium; no absorption bands related to iron were observed. Using a combination of spectroscopic and microscopic methods, the samples were adequately identified as natural emeralds, with Colombia as their most probable source. Nineteen coloured gems adorning a 19th century pendant were examined. Natural multiphase inclusions with jagged outlines were observed in all samples under microscope. Raman bands of beryl appeared for all samples with 532‐nm laser and with 785‐nm laser, at higher wavenumber, water‐related vibrations linked with emeralds containing low concentration of alkali elements. UV–Vis–NIR absorption bands related to chromium and vanadium were detected in all samples. All 19 gems found to be natural emeralds most likely from Colombia.
Raman spectroscopy is considered as one of the most appreciated analytical techniques in the cultural heritage research field, thanks to some of its favourable characteristics such as the relatively quick time of analysis, identification of both inorganic and organic molecules. The necessity of conducting the research non‐destructively on‐site and directly on the artefact brought the technique out of the laboratory. Since 2004, when the first non‐commercial mobile Raman instrument for in situ applications on cultural heritage objects was realized, years of continuous technical and instrumental developments have passed. Today, on‐site Raman spectroscopy is considered as a cornerstone technique for the documentation of materials of works of art and the assessment of their conservation state without jeopardizing the integrity of the artefact. This paper reviews some of the breakthroughs of Raman analysis of cultural heritage objects, conducted on field (museum environment, outdoors and archaeological complexes). In this work, we provide an overview of recent achievements and trends in mobile Raman spectroscopy for studying objects of cultural heritage.
Reviewing the analytical strategies used in the study of cultural heritage assets such as movable artworks and archaeological items, and immovable objects like mural paintings, archaeological sites and historical buildings, this book pays particular attention to analytical methodology. It is not always necessary to use new and sophisticated instrumentation, what is important is how the instruments are used to obtain reliable, reproducible and repetitive results in view of the problems to be solved. The book considers the influence of the environment on the conservation state including degradation and how modern analytical methods have improved the analysis of materials. It emphasizes multi-method approaches on a range of materials, an approach that is of keen interest to those working in conservation practice.
Primarily aimed at final year undergraduate study and masters level students, it would also be useful as supplementary reading for postgraduates and academics who require analytical techniques to enhance their research.
The reliquary bust of Saint Lambert, hosted in the Treasure of the Liège Cathedral, was produced in the early 15th century. This exceptional goldsmithery piece is covered with gold‐coated silver, and decorated by approximately 400 stones, analysed by Raman and pXRF techniques to determine their mineralogical and chemical composition. The results confirm the identification of one hundred pearls, twenty‐six rock crystals, ten amethysts, two diamonds, and numerous glass beads with a green, blue, colourless, turquoise, orange or red colour. The glass beads show a soda‐lime composition, confirming that they are contemporary of the bust and imported from Venice, as reported by historical sources. Orange beads show a lead composition and the red stone a triplet with quartz, indicating that they were added to the bust later. The cutting of gems and beads shows also a significant evolution. The metal contains approximately 60% of Au and 40% of Ag. The origin of gemstones was difficult to establish, due to the absence of characteristic trace elements, but the chemical elements used for the manufacture and colouring of the beads were determined. This study confirms the trade of stones between Liège and Venice during medieval times.
An in situ archaeometrical campaign was organized in 2018 for the physicochemical analysis of the exceptional Mosaico de los Amores of the Cástulo archaeological site (Linares, Spain). Several mobile instruments were brought on the field to investigate the colourful tesserae of the mosaic. The main aim of the current research paper is the comparison of different mobile instruments and their applicability on measuring in open air environments. In this study, the comparison of four mobile Raman instruments, using different excitation lasers and technologies, is discussed. Three portable, the EZRaman‐I dual Raman analyser from TSI Inc. (USA), the i‐Raman® EX from BWTEK (USA), and the BWS445‐785S InnoRam™ Raman spectrometer from BWTEK (USA), and one handheld system, the Bravo Raman spectrometer from Bruker (Europe), are compared in terms of their characteristics, applicability, and performance when conducting non‐invasive and non‐destructive analysis. In 2018, an on field archaeometrical campaign was organized in order to physicochemically characterize the colourful tesserae of the Mosaico de los Amores of the Cástulo archaeological site (Linares, Spain). Several instruments were brought on site in order to perform non‐invasive and non‐destructive analysis. In this study, the applicability and performance of four Raman mobile systems, using different excitation lasers and technologies, are discussed.
Archaeometry is the research area on the edge between humanities and natural sciences: it uses and optimises methods from chemistry, spectroscopy, physics, biology, etc. to help answering research questions from humanities. In general, these objects are investigated for several reasons. Besides the fundamental interest to know about the materials that were used in the past, the study of artefacts can support their preservation, either by helping to select optimal storage or display conditions, either by investigating decay pathways and suggesting solutions. Other reasons for art analysis include provenance studies, dating the artefact or identifying forgeries. Since several years, Raman spectroscopy is increasingly applied for the investigation of objects of art or archaeology. The technique is well-appreciated for the limited (or even absent) sample preparation, the relative straightforward interpretation of the spectra (by fingerprinting - comparing them against a database of reference pigments) and its speed of analysis. Moreover, the small spectral footprint – allowing to record a molecular spectrum of particles down to 1 µm, the typical size of pigment grains – is certainly a positive property of the technique. Raman spectroscopy can be considered as rather versatile, as inorganic as well as organic materials can be studied, and as the technique can gather information on crystalline as well as on non-crystalline phases. As a consequence, Raman spectroscopy can be used to study antique objects and twentieth-century synthetic (organic) materials – illustrating the wide range of applications. Finally, the technique is as non-destructive, provided the laser power is kept sufficiently low not to damage the artwork. In literature, the terms “non-invasive” and “non-destructive” are used, where the first term means that no sampling is involved, and the latter term indicates that no sample is taken or that during analysis the sample is not consumed (destroyed) and remains available for further analysis.
Raman microspectroscopy conducted with transportable/mobile instruments allows for the non-invasive identification of amorphous and crystalline phases of ancient masterpieces and outstanding artworks (objects, paintings and décor, building parts, etc.). Resonance Raman spectroscopy detects chromophore and dye traces. On the basis of examples (enamelled glass and pottery, enamelled metal, patinated/corroded metal, stained glass, sculptures, paintings, pastels and drawings) this mini-review discusses the main parameters (laser and optics choice, experimental procedure, etc.) and shows how phase identification contributes to a better understanding of innovant technology exchanges.
Origin of gemstones is a key aspect not only in gemological field but also in Cultural Heritage studies, for the correct evaluation of precious artifacts. The studies on gems require the application of non-invasive and non-destructive methods; among them, portable spectroscopic techniques has been demonstrated as powerful tools, providing a fingerprint of gems for origin and provenance determination. In this study, portable XRF spectroscopy has been applied to test the potential of the technique for the origin determination of corundum gems. The obtained results allowed distinguishing natural and synthetic rubies and sapphires.
We present examples of application of a recently developed portable sequentially shifted excitation Raman spectrometer for identifying three series minerals and carbonaceous matter. Those include compounds of relevance for the fields of geobiology and exobiology: sulfates and carbonates, organic minerals, and carbonaceous matter. It is demonstrated that unambiguous obtaining of Raman spectra can be achieved fast and with the gain in eliminating potential fluorescence features. Copyright © 2017 John Wiley & Sons, Ltd.
Portable Raman spectroscopy is applied for the first time on rock art paintings from hunter-gatherers in three different provinces in Patagonia, Argentina (Neuquén, Río Negro and Chubut). Selected archaeological sites were examined, revealing the local ‘palette’ of the native population and, if possible, the technology used. Moreover, alteration products were investigated to obtain valuable information for a better conservation and preservation of these magnificent rock art paintings. During a single research campaign, 16 shelters and one cave were investigated, which makes this study as one of the most condensed expeditions on measuring rock art paintings. Here, we evaluate the use of our portable Raman instrument to analyse rock art paintings under extreme conditions in Patagonia, Argentina. Several improvements are proposed to maximize the quality of the research output in such condensed expeditions. Copyright
A brief review of application of X-ray fluorescence analysis (XRFA) to fine and applied arts related to Czech cultural heritage is presented. The Department of Dosimetry and Application of Ionising Radiation of CTU-FNSPE has used XRFA in collaboration with various Czech institutions dealing with cultural history for many kinds of artefacts, (e.g., Roman and medieval brass, gemstones and noble metals from the sceptre of one of the faculties of the Charles University in Prague, millefiori beads, etc.). In some cases, a combination of various other techniques alongside XRFA was used for enhancing our knowledge of a measured object.
Minerals, as raw structural materials or pigments, play a fundamental role in archaeometry, for the understanding of nature, structure and status of an artefact or object of interest for cultural heritage. A detailed knowledge of the mineral phases is crucial to solve archaeological problems: Raman spectroscopy is a powerful investigation technique and has been applied extensively in the last 30years on mineral identification and on pigment degradation. Here we report an updated review, covering the last decade, of the applications of Raman techniques to issues in which raw minerals, including mineral pigments, are involved. Particular attention is devoted to cases where the Raman analysis of minerals is deeper than a simple identification of the phases present in an archaeological or artistic object.
Mobile instrumentation is of growing importance to archaeometry research. Equipment is utilized in the field or at museums, thus avoiding transportation or risk of damage to valuable artifacts. Many spectroscopic techniques are nondestructive and micro-destructive in nature, which preserves the cultural heritage objects themselves. This review includes over 160 references pertaining to the use of mobile spectroscopy for archaeometry. Following a discussion of terminology related to mobile instrumental methods, results of a literature survey on their applications for cultural heritage objects is presented. Sections devoted to specific techniques are then provided: Raman spectroscopy, X-ray fluorescence spectrometry, Fourier transform infrared spectroscopy, laser-induced breakdown spectroscopy, and less frequently used techniques. The review closes with a discussion of combined instrumental approaches.
Technology development over the last years has led to significant improvements in the quality and flexibility of portable instruments. Notably, handheld energy-dispersive X-ray fluorescence (ED-XRF) spectrometry has seen a bloom both in terms of technical development and applications, ranging from the field of mineral exploration to archaeology, environmental science, paleoclimatology and forensic science. However, the field of carbonate geoscience has not yet taken the capability and flexibility of this tool to its advantage. This study developed a methodology for the application of handheld XRF on carbonate. An assessment was made in terms of measurement time, sample preparation and weathering of outcrops. Correction equations are presented for elemental concentrations of Ca, Ti, Fe, Mn, Zn, Al, K, Mg, Ba, Sr, Rb and Si that were derived from calibration based on a series of carbonate lab standards. Weathering can pose a significant issue for in situ measurements on field carbonate outcrops, since weathering impacts on the concentrations of Ca, Mg, Ti and Al in the carbonate rocks. Therefore, we advise that XRF is used on fresh rock chips that are hammered from the carbonate outcrop to take advantage of making measurements in situ and at the same hand ensuring reliable quantitative results. This method allows a rapid and inexpensive geochemical characterization of carbonate, which opens opportunities for stratigraphic, sedimentological, paleoenvironmental and diagenetic studies in extensive study areas.
The aim of this paper is to provide an overview of advances in the field of Raman spectroscopy as reflected in articles published each year in the Journal of Raman Spectroscopy as well as in trends across related journals publishing in this research area. The context for this review is derived from statistical data on article counts obtained from Thomson Reuters ISI Web of Knowledge by year and by subfield of Raman spectroscopy. Additional information is gleaned from presentations featuring Raman spectroscopy presented at the International Conference on Advanced Vibrational Spectroscopy in Kobe Japan in August 2013 and at SCIX 2013 sponsored by the Federation of Analytical Chemistry and Spectroscopy Societies in Milwaukee, Wisconsin, USA, October 2013. Papers published in the Journal of Raman Spectroscopy in 2012 are highlighted in this review and reflect topics and advances at the frontier of Raman spectroscopy, a field that is expanding rapidly as a sensitive photonic probe of matter at the molecular level in an ever widening sphere of novel applications. Copyright (c) 2013 John Wiley & Sons, Ltd.
In recent years, the use of mobile Raman equipment as an archeological, artistic, and conservation tool has largely increased due to the possibility to obtain quick and nondestructive compositional analysis on precious, vulnerable, and unique art objects. In particular, art and archeological museums can take great advantage in carrying out in situ measurements in short times and without moving the artifacts. In this work, we report on the Raman measurements carried out by portable instruments on an important jewelry collection dated back to 17th–18th centuries and preserved in the Messina Regional Museum (Sicily, Italy) with the goal to verify the identification of the gems and gemological materials of the collection, previously made by conservators. Although most of the previous identifications were confirmed, some important reclassifications have been proposed. Finally, interesting and unusual combinations of different materials were detected in some jewels. Copyright © 2015 John Wiley & Sons, Ltd.
This review covers developments in the analysis of chemicals, metals and functional materials. We have strengthened the criticality of this review and have included only those papers dealing with advances in the analysis of these materials. Other papers which the reader may find useful because they cover interesting applications are included in the tables. It follows last year's review1 and should be read in conjunction with other reviews in the series.2–5 Significant developments during this review period include the continued expansion of the use of LIBS in remote analysis, especially of explosives, metals and nuclear materials. The stand-off capability of the technique makes it very desirable in these areas. The use of chemometrics for removing substrate interferences is proving to be effective in making the technique more robustly quantitative and a number of papers developing the understanding of plasma physics to improve the technique of LIBS are reviewed. Multiple spectroscopic techniques are being developed to maximize the knowledge which can be derived from the analysis, especially of high value samples, for example the combination of LIBS and Raman measurements to gain molecular and atomic spectral information. Advances in the analysis of nanomaterials and single particles are reviewed and papers dealing with single particle analysis, field flow fractionation and related techniques coupled with ICP-MS are advancing the analytical chemistry in the field. These techniques are also increasingly being used in vivo and in biological areas. Depth profiling of semiconductor materials is an important area during this review period, especially for the determination of dopant elements. There are significant changes to the writing team this year. Mike Hinds has left the team and we are pleased to welcome Bridget Gibson and Ian Whiteside.
In the last decade, Raman spectroscopy has been used for routine investigation for gemmological purposes, being non-destructive and non-invasive. In addition, this technique grants short measurement times without any sample preparation. In this context, this work is focused on the spectroscopic characterization of different kinds of blue gems, including sapphires, by comparing the performance of a handheld Raman instrumentation along with a micro-Raman spectrometer, with the aim to provide gemmological certification and to get information on the provenance of the gems. The main goal of the present study is to identify imitation gems and to distinguish between natural and synthetic sapphire; in this latter case, micro-Raman measurements were fundamental for the characterization of the inclusions. Moreover, the chemical composition of blue gems has been obtained by portable XRF technique. The obtained data show that a portable Raman spectrometer can be recommended as a fast and easy instrument to discriminate sapphire from imitations. Copyright © 2014 John Wiley & Sons, Ltd.
A silver Torah shield fitted with a set of precious stones and glass imitations crafted in Poland in the first half of the 19th century was investigated using two of the currently distributed portable and relatively low-cost Raman spectrometers in situ at the Jewish Museum in Prague. Observed Raman peaks corresponded well (+/− 3 cm−1) to the reference values. The hand-held instruments operated at 785- and 532-nm laser excitations showed good performance in the fast and unambiguous identification of nearly 60 stones which were fitted on the shield: one blue aquamarine, three purple amethysts, thirteen red garnets (all classified as high-percentage almandines), three white pearls, fifteen pieces of red coral and five chalcedonies (one white and four red). All of the other stones were identified as colored glass. The rather chaotic mixture of stones of various colors, cuts and sizes and the total volume of imitation glass support the theory that the mounted stones were gathered from Jewish households and donated for the adornment of the shield. The common portable Raman instruments represent an ideal tool for the quick and accurate identification of gemstones mounted in historical artifacts in situ in the framework of museum or collection sites in a non-destructive way. Copyright © 2014 John Wiley & Sons, Ltd.
The applications of analytical Raman spectroscopy in the characterisation of materials associated with archaeologically excavated artefacts, forensic investigations of drugs of abuse, security and crime scenes, minerals and rocks and future astrobiological space missions are now well established; however, these applications have emphasised the need for new developments in the area of miniaturised instrumentation which extends the concept and breadth of the analytical requirement to facilitate the provision of data from 'in field' studies. In this respect, the apparently unrelated themes of art and archaeology, forensic science, geological science and astrobiology as covered by this review are unified broadly by the ability to record data nondestructively and without resorting to sampling and the subsequent transfer of samples to the analytical laboratory. In studies of works of art there has long been a requirement for on-site analysis, especially for valuable paintings held under strict museum security and for wall paintings which cannot physically be removed from their setting; similarly, the use of portable Raman spectroscopy in archaeological and geological field work as a first-pass screening device which obviates the necessity of multiple and wasteful specimen collection is high on the wish-list of practicing spectroscopists. As a first-pass screening probe for forensic crime scenes, Raman spectroscopy has proved to be of inestimable value for the early detection of dangerous and prohibited materials such as drugs of abuse, explosives and their chemical precursors, and banned contraband biomaterials such as ivories and animal products; in these applications the advantage of the Raman spectroscopic technique for the recognition of spectral signatures from mixtures of inorganic and organic compounds is paramount and not afforded by other less portable instrumental techniques. Finally, in astrobiological work, these requirements also apply but with the additional prerequisite for system operation remotely - often over distances of several hundred million kilometres - as part of instrumental suites on robotic spacecraft and planetary landers; this necessitates robust and reliable instrumentation for the observation of unique and characteristic spectral features from the planetary geological surface and subsurface which are dependent on the assignment of both biological and geological band signatures.
An analytical procedure relying on micro-energy dispersive X-ray fluorescence spectrometry (μ-EDX) was evaluated for the quantitative determination of macro-, micronutrients and beneficial elements in pressed pellets of plant materials. For testing purposes, leaves from 23 varieties of sugar cane, previously analyzed by validated reference methods, based on wet decomposition procedures followed by ICP OES measurements were used. Linear correlations between analyte mass fractions in the tested samples and the corresponding μ-EDX intensities were obtained for P, K, Ca, S, Fe, Mn and Si with regression coefficients ranging from 0.9501 to 0.9933. Furthermore, the coefficients of variation of results in the 0.3 to 16% range (n = 3 sampling lines, 30 sampling sites per line), the spatial resolution of 50 μm per site and the suitable detection limits for these analytes were additional features that demonstrated the performance of the proposed procedure as a useful tool for plant nutrient diagnosis. In addition, the results also indicate that μ-EDX can be recommended as a cross-validation method for analysis of plant materials, owing to its inherent non-destructive capability and, particularly, when dealing with analytes' micro-heterogeneity evaluation within the samples.
Commercial quantities of gem-quality chrysoprase and green prase opal (nickel-bearing chalcedony and common opal, respectively) have been recovered from altered serpentinite deposits near Haneti, Tanzania. Material studied for this report came from the largest mine, located on top of lyobo Mountain, which has been actively exploited for two decades. Although somewhat similar in color and appearance, chrysoprase and prase opal can easily be distinguished from one another by differences in refractive index (∼1.55 vs. ∼1.45) and specific gravity (∼2.60 vs. ∼2.11). Chrysoprase makes up the vast majority of the output, and the mine shows good potential for continued production.
The gemstones that adorn a late-16th-century ciborium from Einsiedeln Abbey in Einsiedeln, Switzerland, were investigated by nondestructive gemological methods and EDXRF and Raman spectroscopy at the Collections Center of the Swiss National Museum. The ciborium is decorated with 17 colored stones: 10 almandine garnets, four grossular garnets, and three sapphires. Inclusions in the sapphires and a historic description of the piece suggest a Sri Lankan origin for the gems.
Two ecclesiastical objects of the late Gothic period (1350-1520) were investigated to identify the gemstones that adorn them. Both are from the treasury of Basel Cathedral (Basler Münster, Basel, Switzerland). To avoid potential damage, the identifications were conducted using only optical microscopy and Raman spectroscopy. Most of the mounted materials were found to be varieties of quartz, either as polished single pieces or as doublets with evidence of what may once have been dyed cement. Glass of various colors was also identified, as were peridot, sapphire, garnet, spinel, and turquoise.
The crystal structures of synthetic pyrope (Mg3AI2Si3O12), almandine (Fe3AI2Si3O12), and the solid-solution garnet compositions Py80-Alm20, Py60-Alm40, and Py20-Alm80 have been refined in space group Ia3d from high-precision X-ray diffraction data with sin 0/l > 0.4 A-I measured at 100 and 293 K. There is no indication of lower symmetry for pyrope, almandine, or solid-solution members. Experimentally determined atomic coordinates and displacement parameters for the solid-solution compositions are in good agreement with those linearly interpolated from the end-members. Thus there are no apparent structural features that could account for substantial nonideal enthalpies of mixing in the system pyrope-almandine. The tetrahedral rotation angle is inversely correlated with the X-O distance. Fe2t substitution on the eight-coordinated X site of pyrope, or increasing temperature, decreases the rigid tetrahedral rotation in garnet. The large and anisotropic dis-placement parameters for the X-site cations in garnet are mainly a result of anisotropic thermal vibrations along the longer X-O bonds, which produce nonrigid polyhedral behavior for the dodecahedral site. The tetrahedra and octahedra behave as rigid bodies. These strong vibrations of the former give rise to the relatively large heat capacities and third-law entropies in garnet. Previous proposals concerning subsite dodecahedral ordering in pyrope must be revised.
A funerary gold mask from the Museum of Sicán, Ferrañafe, Peru was analyzed in 30 different areas using a portable equipment using energy-dispersive X-ray fluorescence. It was deduced from the measurements that the main sheet of the mask and the majority of the pendants have a similar composition and are made of tumbaga, which means a poor gold alloy enriched at the surface by depletion gilding, and have a similar ‘equivalent’ gilding thickness of about 5 µm. The nose, also on tumbaga, has different composition and a thickness of about 8 µm. The clamps are on gilded or on silvered copper. The red pigment dispersed on the surface of the mask is cinnabar. Copyright © 2009 John Wiley & Sons, Ltd.
Organic minerals, organic acids and NH-containing organic molecules represent important target molecules for astrobiology. Here, we present the results of the evaluation of a portable hand-held Raman spectrometer to detect these organic compounds outdoors under field conditions. These measurements were carried out during the February-March 2009 winter period in Austrian Alpine sites at temperatures ranging between -5 and -25 degrees C. The compounds investigated were detected under field conditions and their main Raman spectral features were observed unambiguously at their correct reference wavenumber positions. The results obtained demonstrate that a miniaturized Raman spectrometer equipped with 785 nm excitation could be applied with advantage as a key instrument for investigating the presence of organic minerals, organic acids and nitrogen-containing organic compounds outdoors under terrestrial low-temperature conditions. Within the payload designed by ESA and NASA for several missions focusing on Mars, Titan, Europa and other extraterrestrial bodies, Raman spectroscopy can be proposed as an important non-destructive analytical tool for the in situ identification of organic compounds relevant to life detection on planetary and moon surfaces or near subsurfaces.
A handheld Raman spectrometer (Ahura First Defender) was tested for the unambiguous identification of biomolecules (pure amino acids, carboxylic acids, saccharides and trehalose) in the solid state under outdoor conditions (including moderate climate conditions as well as cold temperatures and high altitudes). The biomolecules investigated represent important objects of interest for future exobiological missions. Repetitive measurements carried out under identical instrumental setups confirmed the excellent reliability of the Raman spectrometer. Raman bands are found at correct wavenumbers +/-3 cm(-1) compared with reference values. This testing represents the first step in a series of studies. In a preliminary, challenging investigation to determine the detection limit for glycine dispersed in a powdered gypsum matrix, 10% was the lowest content confirmed unambiguously. Clearly there is a need to investigate further the detection limits of Raman spectroscopic analyses of biomolecules in more complex samples, to demonstrate the usefulness or disqualify the use of this technique for more realistic outdoor situations, such as eventual future missions to Mars.
Many of the Raman spectra obtained from areas painted with ultramarine pigments in illuminated manuscript leaves from the 14th century Italian manuscript the Laudario of Sant'Agnese, in the collection of the J. Paul Getty Museum, also contain strong bands not typically associated with this pigment. The source of these features was investigated using a multitechnique analytical approach. Techniques employed include Raman microspectroscopy, scanning electron microscopy with energy-dispersive spectroscopy, electron probe microanalysis, and laser ablation inductively coupled plasma mass spectrometry. The results indicate the presence of diopside (CaMgSi(2)O(6)), a mineral commonly associated with lapis lazuli in nature, and suggest that transition metal dopants in the diopside may be responsible for the Raman features, likely the result of fluorescence with vibronic coupling. The implication of this result with respect to using Raman spectroscopy as a fast, noninvasive, and nondestructive method for determining the geological provenance of natural lapis lazuli pigments used in art is discussed.
Raman spectroscopy is a versatile technique that has frequently been applied for the investigation of art objects. By using mobile Raman instrumentation it is possible to investigate the artworks without the need for sampling. This work evaluates the use of a dedicated mobile spectrometer for the investigation of a range of museum objects in museums in Scotland, including antique Egyptian sarcophagi, a panel painting, painted surfaces on paper and textile, and the painted lid and soundboard of an early keyboard instrument. The investigations of these artefacts illustrate some analytical challenges that arise when analysing museum objects, including fluorescing varnish layers, ambient sunlight, large dimensions of artefacts and the need to handle fragile objects with care. Analysis of the musical instrument (the Mar virginals) was undertaken in the exhibition gallery, while on display, which meant that interaction with the public and health and safety issues had to be taken into account.
Experimental set-up for the non-destructive Raman spectroscopic investigation of a textile banner in the National Museums of Scotland
This article presents the "in situ" and totally non destructive investigation of a wall painting in Santa María de Lemoniz (Biscay, Basque Country, Spain) by Raman microprobe spectroscopy 14 years after its restoration. Although no sample was allowed to be taken, it has been possible to determine the original pigments in the artwork (vermilion, red iron oxide, yellow iron oxide, carbon black, lead white), as well as some degradation products (calcium oxalate dihydrate, anhydrite). For the first time, the mechanism for the transformation of malachite into copper basic sulphates has been ascertained by the integration of Raman data with thermodynamic speciation studies. Moreover, some remarks regarding the unsuitability of the past intervention procedure with regard to the chemical stability of the artwork are made.
Moganite, monoclinic SiO2, is a component of microcrystalline, quartz-bearing, sinters of New Zealand derived from crystallization of non-crystalline and paracrystalline opaline silicas. It occurs at levels of 2 phases present in sinters between 20,000 and 200,000 y old but is generally either absent or below the level of detection in Tertiary sinters. Unambiguous identification of moganite is most readily accomplished by laser Raman spectroscopy; the technique allows individual microtextural elements of a sinter's fabric to be analysed. Conventional scanning X-ray powder diffraction procedures are limited in their ability to discern the characteristic moganite diffraction lines from the very similar quartz pattern, especially in those samples where moganite is at low concentration and/or unanticipated. However, powder diffraction, using a position-sensitive detector system, allows not only the identification of the moganite pattern in the presence of a large proportion of quartz, but also semiquantitative estimates of the different silica phases present in bulk sinter samples of ~450 mg. Moganite is part of the sinter maturation sequence. It occurs as a metastable phase that will ultimately transform to quartz, given sufficient time or a change in ambient conditions.
The experimental procedures and most important conclusions of the first on-site Raman study of the stained glass windows in the upper chapel of the Sainte-Chapelle, Paris are discussed. Some of the windows suffered damage during/after the French Revolution and were partly restored in the 19th century. Measurements were performed with a new portable Raman instrument on colourless, blue and green stained glasses. We illustrate how the Raman signature of the glass makes it possible to distinguish between medieval K/Ca or 19th century restored Na/Ca-based silicates and to determine their weathering degree. This is achieved by means of the extraction of vibrational parameters and then processing them, using chemometric approaches, principal components and cluster variation analyses with varying degrees of complexity. The Raman scattering intensity of weathered glasses is used to determine their relative age. The results differ from those presented in the Corpus Vitrearum Medii Aevi (obtained by visual inspection) and therefore demonstrate the need for updating these reports with modern methods such as in situ Raman spectroscopy.
Questions of identity and provenance of minerals that are parts of masterpieces in museums have become increasingly important in mineralogical and historical studies. Detailed investigations of valuable and unique objects require on-site, nondestructive and noninvasive methods because touching or removing them may cause irreparable damage. A mobile Raman-microprobe has been used to meet these demands for truly in situ mineralogical studies of the large collection of minerals and rocks of the Prussian kings in the Grotto Hall (Grottensaal) of the New Palace (Neues Palais), Park Sanssouci in Potsdam. Minerals on the walls of the Grotto Hall were analyzed to identify them and thereby to complete the data bank of the collection. Fluid and solid inclusions in the interior of a large quartz crystal have been studied to provide evidence of the provenance of the crystal. The fluid inclusions contain aqueous saline solutions, whereas the solid inclusions are needles of anhydrite with a length of about 1.5 mm. The quartz probably originated from an area in the eastern Alps, from the surroundings of Bad Gastein, Austria. This is the first on-site and in situ study of inclusions below the surface of a mineral with a mobile Raman-microprobe outside a laboratory. Copyright © 2006 John Wiley & Sons, Ltd.
Twelve gemstones set into the cover of an elaborately decorated leather-bound manuscript, the Tours Gospel, ‘Evangelia Quatuor’, held in the British Library (Add. MS. 11848), were identified by Raman microscopy to be composed of silica, amethyst, emerald (probable, 3), iron garnet (3) and sapphire (3), one not being identified. The brilliant illuminations within the manuscript (ca 825 AD) were established by Raman studies at 215 locations on 13 folios to have been painted with a restricted palette, which included carbon black, indigo, lead white, minium, orpiment and vermilion, together with certain mixtures of the above pigments. Gold was also used but, notably, not lazurite. The palette was compared with those found for the earlier Lindisfarne Gospels (ca 715 AD), part of a later Anglo-Saxon manuscript (ca 920 AD), a Paris Bible (1267 AD) and certain Gutenberg Bibles (1455 AD). Copyright © 2004 John Wiley & Sons, Ltd.
A selection of 22 rare Chinese cloisonné enamels, from fifteenth century to nineteenth century A.D., has been studied on-site in the storage rooms of the musée des Arts décoratifs in Paris. The Raman signatures of the transparent and/or opacified glass matrix are discussed and compared with those that were previously recorded on glazed pottery, enameled and stained glasses. Enamels mostly belong to lead-based potash-lime glasses. Three different compositions, lead-potash-lime (fifteenth, sixteenth, eighteenth and nineteenth century), soda-rich (sixteenth–seventeenth century) and soda-lime (seventeenth century) are identified according to the wavenumber maxima of the SiO stretching and bending multiplets. Most of the pigment signatures are similar to those recorded on ceramic glazes and glass enamels, which proves the link between the technologies but a specific opacifier is observed: fluorite (CaF2). Naples Yellow pigment variations give characteristic signatures. Additionally, a comparison is made with Limoges enamels (sixteenth–nineteenth century A.D.). Copyright © 2009 John Wiley & Sons, Ltd.
A variety of treated and synthetic gem materials are encountered today in the jewelry marketplace in increasing quantities. Although normally entering into the market with correct information, in some cases these materials are sold with incorrect or inaccurate information on their identity. In some cases, they exhibit appearances that correspond closely to those of valuable untreated, natural gemstones. Although they can display certain distinctive gemological characteristics, some treated and synthetic gem materials can be difficult for jewelers to recognize, especially when these individuals lack gemological training and access to standard gem-testing methods and equipment. In such instances, testing by a professional gemological laboratory may be required. Accurate gem identification and complete information disclosure are essential in the jewelry trade to maintain both the commercial value of natural gemstones and the confidence among consumers who are considering gemstone purchases. The goal of most current gemological research is to provide practical means of gem identification for jewelers and gemologists to help insure integrity in the international gemstone trade. To support this goal, research on gem materials increasingly relies upon characterization with modern analytical tools such as chemical analysis, various spectroscopy methods, and other scientific techniques.
Spectroscopic techniques were applied to the study of natural and synthetic gems, especially rubies. It is shown that among the spectroscopic techniques available, micro-Raman spectroscopy is the easiest to use and the most efficient. Moreover, this technique can be applied to mounted gems without removing them from the setting. However, complementary methods such as micro-Fourier transform infrared, micro-fluorescence, electron probe and NMR spectroscopy, were used in order to characterize the gems more thoroughly in order to differentiate between natural and synthetic specimens. © 1997 John Wiley & Sons, Ltd.
On the north coast of present-day Peru flourished approximately between 50 and 700 AD the Moche civilisation. They were sophisticated metalworkers and are considered the finest producers of jewels and artefacts of the region. The Moche metalworking ability was impressively demonstrated by the excavations of the ‘Tumbas Reales de Sipán’, carried out by Walter Alva et al. in 1987. About 50 metal objects from these excavations, now at the Museum ‘Tumbas Reales de Sipán’, in Lambayeque, North of Peru, were analysed with a portable equipment which uses energy-dispersive X-ray fluorescence (EDXRF). This portable equipment is mainly composed of a small-sized X-ray tube and a thermoelectrically cooled, small-sized X-ray detector. Standard samples of gold and silver alloys were employed for calibration and quantitative determination. The analysed artefacts are mainly gold, silver and copper alloys, gilded copper and tumbaga, the last being a poor gold alloy enriched at the surface by depletion gilding, i.e. by removing copper and silver from the surface. In the case of gold, silver and copper alloys, their composition was determined by the EDXRF analysis in the usual manner, i.e. by employing standard alloys. In the case of gilded copper or tumbaga, the ratios Cu(Kα/Kβ) and (Au-Lα/Cu-Kα) were accurately determined from the X-ray spectra, first to clearly distinguish gilded copper from tumbaga and then to determine the gilding thickness or an ‘equivalent gilding thickness’ in the case of tumbaga. The combination of the two ratios is a clear indication of the nature of the alloy (gold, gilded Cu or tumbaga) and allows an accurate measurement of the gilding thickness in the case of gilded copper objects or, in the case of tumbaga, the ‘equivalent’ gold thickness was measured to be ∼2.8 µm. From all measurements, the mean approximate composition and thickness of Sipán alloys is the following: Copyright
Iznik tiles dated from the 16th century, copies of tiles and pottery of Théodore Deck from the 19th century and also tiles without any information on their origin were analyzed with both laboratory and portable Raman instruments. As the original tiles are generally fixed on the walls of historical buildings, the portable Raman spectrometer is more convenient for the analysis but the information obtained from the spectra is not very useful because of the medium resolution and complex baseline of the instrument in spite of its speed and ease of use. The Raman signature of the glazes is the most pertinent and easily accessible fingerprint of the artifacts. The differentiation between Iznik ceramics and other samples could be made with Raman spectrometers, according to the specific signature of SiO stretching and bending bands of Iznik glazes. Copyright © 2009 John Wiley & Sons, Ltd.
A selection of 15 painted enamels, most of which belong to Limoges productions, from 1500 to 1900 A.D., has been studied on-site in the storage rooms of musée des Arts décoratifs in Paris. The Raman signatures of the transparent and/or opacified glass matrix are discussed and compared with those which were previously recorded on glazed pottery, enamelled and stained glasses as well as Chinese cloisonné enamels. Analysed enamels mostly belong to soda-lime-based glass. Three types of compositions such as soda-lime (fifteenth to sixteenth century), soda-rich (fifteenth, sixteenth/nineteenth centuries) and lead-potash-lime (sixteenth and nineteenth centuries) are identified on the basis of the Raman signature of the glaze according to the wavenumber maxima of the SiO stretching and bending multiplets. The pigment signatures are similar to those recorded on ceramic glazes and glass enamels, which proves the similarity of the technologies. Cassiterite as an opacifier and hematite red and Naples yellow pigment variations give characteristic Raman signatures. The presence of lead arsenate as a pigment opacifier in nineteenth-century samples is confirmed. Attempts are made to establish tools for the differentiation between genuine artefacts and nineteenth-century restoration or fakes. Copyright © 2010 John Wiley & Sons, Ltd.
An in situ non-destructive study of the reliquary cross called Heinrich's cross dating from the late Middle Ages (first quarter of the 11th century) was performed using a mobile Raman microspectrometer in order to identify the adorning gemstones. Heinrich's cross, today kept in the Museum of Applied Arts (Kunstgewerbemuseum, KGM), Berlin, is considered to be one of the most precious sanctuaries of the treasury of Basel Cathedral. It bears 68 gemstones that are mounted at the both sides of the cross. Silver pearls alternate with gemstones. Analyses were made with a fibre-optic System-100 Raman-analyser (Renishaw), directly in the museum, without the need to remove the object. Strengths and weaknesses of the use of a mobile Raman microspectrometer for the investigation of art and archaeological objects within the museum are discussed since only relatively few analyses using mobile spectrometers have so far been performed in situ. In this study, the determination of the nature of the gems generally confirms the identification based on previous optical observations. Most of the mounted materials were found to be glass paste or quartz varieties. Some garnets, sapphires and interestingly rubies were also identified. The use of rubies is rare in the Middle Ages. Generally, green, blue and dark-coloured stones were difficult to identify using this Raman set-up (λ = 785 nm) because of fluorescence phenomena, and 11 gems could not be identified unambiguously. This study shows the importance of coupling optical observations with Raman spectroscopy for gemstone identification. These results together with those of other fine objects originating from the same treasury show that mainly quartz and glass paste were used on very valuable and outstanding religious items from the Middle Ages to the Gothic period. However, it could not be determined if they represent gems replaced during later times or original ones that were mainly chosen for their colour and not necessarily for their value. Copyright © 2004 John Wiley & Sons, Ltd.
The infrared absorption spectrum of amethyst in the region of stretching vibrations of X–OH groups reveals several bands that
have been used for the separation of natural from synthetic amethyst. The intensity and shape of these bands have been measured
as a function of crystallographic orientation. Using a resolution of 0.5 cm−1 the 3595 cm−1 band is present in all infrared spectra of natural amethyst and in some rare synthetic ones. If present in synthetic amethyst,
its full width at half maximum (FWHM) is about 7 cm−1 whereas it is about 3 cm−1 in all natural samples. This new criterion, unlike the previous ones, seems appropriate to separate natural from synthetic
amethyst in all cases.
The characteristics of inclusions in natural and synthetic gems are distinct owing to their different forming mechanisms and
can be utilized to distinguish gems from different localities. In addition, intensive studies on inclusion characteristics
of natural gems could identify their geographical origins and provide valuable information on gem synthesis. In this paper
synthetic gems (synthetic star-spangled sapphire and emerald) and natural gems from various locations including natural sapphire
from Thailand and Australia, and natural aquamerine from Mufushan, Hunan Province, and Ailaoshan, Yunnan Province, were selected
for the comparative study of inclusions. Significant research results have been achieved, thus providing the important basis
for distinguishing natural from synthetic gems.
Handheld Raman spectrometers (Ahura First Defender XL, Inspector Raman DeltaNu) permit the recording of acceptable and good quality spectra of a large majority of minerals outdoors and on outcrops. Raman spectra of minerals in the current study were obtained using instruments equipped with 785 nm diode lasers. Repetitive measurements carried out under an identical instrumental setup confirmed the reliability of the tested Raman spectrometers. Raman bands are found at correct wavenumber positions within ±3 cm(-1) compared to reference values in the literature. Taking into account several limitations such as the spatial resolution and problems with metallic and black and green minerals handheld Raman spectrometers equipped with 785 nm diode lasers can be applied successfully for the detection of minerals from the majority of classes of the mineralogical system. For the detection of biomarkers and biomolecules using Raman spectroscopy, e.g. for exobiological applications, the near infrared excitation can be considered as a preferred excitation. Areas of potential applications of the actual instruments include all kind of common geoscience work outdoors. Modified Raman systems can be proposed for studies of superficial or subsurface targets for Mars or Lunar investigations.
Being nondestructive and requiring short measurement times, a low amount of material, and no sample preparation, Raman spectroscopy is used for routine investigation in the study of gemstone inclusions and treatments and for the characterization of mounted gems. In this work, a review of the use of laboratory Raman and micro-Raman spectrometers and of portable Raman systems in the gemology field is given, focusing on gem identification and on the evaluation of the composition, provenance, and genesis of gems. Many examples are shown of the use of Raman spectroscopy as a tool for the identification of imitations, synthetic gems, and enhancement treatments in natural gemstones. Some recent developments are described, with particular attention being given to the semiprecious stone jade and to two important organic materials used in jewelry, i.e., pearls and corals.
Figure
Pictures of a pyrope-almandine garnet and of a needle-shaped inclusion. The Raman spectrum of the inclusion is characteristic of rutile
X-ray fluorescence spectroscopy (XRF) and Raman spectroscopy have been used to examine 15th century mediaeval and 16th century renaissance vault paintings in the Our Lady's Cathedral (Antwerp, Belgium) in view of their restoration. The use of mobile instruments made it possible to work totally non-destructively. This complementary approach yields information on the elemental (XRF) and on the molecular composition (Raman) of the pigments. For the 15th century vault painting the pigments lead-tin yellow (Pb(2)SnO(4)), lead white (2PbCO(3)xPb(OH)(2)), vermilion (HgS), massicot (PbO) and azurite (2CuCO(3).Cu(OH)(2)) could be identified. The pigments used for the 16th century vault painting could be identified as red lead (Pb(3)O(4)), hematite (Fe(2)O(3)), lead white (2PbCO(3)xPb(OH)(2)) and azurite (2CuCO(3)xCu(OH)(2)). For both paintings the presence of the strong Raman scatterer calcite (CaCO(3)) resulted in a difficult identification of the pigments by Raman spectroscopy. The presence of gypsum (CaSO(4)x2H(2)O) on the mediaeval vault painting probably indicates that degradation took place.
A rapid system to obtain molar compositions of minerals belonging to the garnet group by means of Raman spectroscopy is illustrated here. A series of standard garnets, whose composition was determined by means of Wavelength Dispersive System (WDS) electron microprobe measurements, was used to correlate the wavenumbers of the different Raman peaks with chemical composition. A simple software routine was then developed in order to obtain garnet molar composition starting from the Raman spectrum, based on the assumption that in a solid solution belonging to the garnet family the Raman wavenumbers are linear combinations of end member wavenumbers, weighted by their molar fraction. The choice of the Raman bands used for the calculations and their behaviour are also discussed. The method, called MIRAGEM (Micro-Raman Garnets Evaluation Method), was then tested on a second series of garnets with satisfactory results.
Raman spectral signatures have been obtained in situ for a series of minerals using portable Raman instruments. Cerussite, anglesite, wulfenite, titanite, calcite, tremolite, andradite and quartz were detected using portable Raman spectrometer First Defender XL (Ahura). Baryte, almandine and realgar Raman spectra obtained by this instrument in the field were compared to the data measured by the other mobile Raman instrument Inspector Raman (DeltaNu). Bench Raman dispersive microspectrometer (InVia Reflex, Renishaw) was used for comparative purposes. All spectra were obtained using a 785nm diode excitation. Although displaying lower spectral resolution comparing with the laboratory confocal instrument both portable instruments permit unambiguous detection of minerals in the field. These possibilities designate portable Raman machines as excellent tools for field geological applications. Miniaturised Raman instrument combined with LIBS will be included in the payload of the EXO Mars mission and would open interesting research possibilities in other in situ field planetary studies.
In archaeometry, one of the main concerns is to extract information from an art object, without damaging it. Raman spectroscopy is being applied in this research field with recent developments in mobile instrumentation facilitating more routine analysis. This research paper evaluates the performances of five mobile Raman instruments (Renishaw RA100, Renishaw Portable Raman Analyser RX210, Ocean Optics RSL-1, Delta Nu Inspector Raman, Mobile Art Analyser--MArtA) in three different laboratories. A set of samples were collected, in order to obtain information on the spectral performances of the instruments including: spectral resolution, calibration, laser cut-off, the ability to record spectra of organic and inorganic pigments through varnish layers and on the possibilities to identify biomaterials. Spectra were recorded from predefined regions on a canvas painting to simulate the investigation of artworks and the capabilities to record spectra from hardly accessible areas was evaluated.
The Faculty of Science of Charles University
- F Čech
F. Čech, The Faculty of Science of Charles University 1920–1980:
History, Present, Perspectives [in Czech], Charles University,
Prague, 1981.
- G Simsek
- P Colomban
- V Milande
- J Raman Spectrosc
G. Simsek, P. Colomban, V. Milande, J. Raman Spectrosc. 2010,
41, 529.
[11] P. Vandenabeele, J. Tate, L. Moens, Anal. Bioanal. Chem. 2007,
387, 813.
- J Jehlička
- A Culka
- P Vandenabeele
- H G M Edwards
J. Jehlička, A. Culka, P. Vandenabeele, H. G. M. Edwards, Spectrochim.
Acta A 2011, 80, 36.
- D Bersani
- P P Lottici
D. Bersani, P. P. Lottici, Anal. Bioanal. Chem. 2010, 397, 2631.
- J Jehlička
- P Vítek
- H G M Edwards
- M Heagraves
- T Čapoun
J. Jehlička, P. Vítek, H. G. M. Edwards, M. Heagraves, T. Čapoun,
Spectrochim. Acta A 2009, 73, 410.
- A Deneckere
- W Schudel
- M Van Bos
- H Wouters
- A Bergmans
- P Vandenabeele
- L Moens
A. Deneckere, W. Schudel, M. Van Bos, H. Wouters, A. Bergmans,
P. Vandenabeele, L. Moens, Spectrochim. Acta A 2010, 75, 511.
Handbook of Gem Identification
- R T Liddicoat
R. T. Liddicoat, Handbook of Gem Identification, Gemological Institute
of America, Santa Monica, 1993.
Gems: Their Sources, Descriptions and Identification
- R Webster
R. Webster, Gems: Their Sources, Descriptions and Identification (5th edn),
Butterworth-Heinemann, Oxford, 1994.
- K J Kingma
- R J Hemley
K. J. Kingma, R. J. Hemley, Am. Mineral. 1994, 79, 269.
- J F White
- J F Corvin
J. F. White, J. F. Corvin, Am. Mineral. 1961, 46, 112.
- O Dreher
O. Dreher, Das Farben des Achates, in Agate: Physical Properties and
Origin, Archaeology and Folklore, (Eds: O. C. Farrington, B. Laufer),
Field Museum of Natural History, Chicago, 1927.
- Z Petrová
Z. Petrová et al.
wileyonlinelibrary.com/journal/jrs
Copyright © 2012 John Wiley & Sons, Ltd.
J. Raman Spectrosc. (2012)
- M Pérez-Alonso
- K Castro
- J M Madariaga
M. Pérez-Alonso, K. Castro, J. M. Madariaga, Anal. Chim. Acta 2006,
571, 121.
Method of producing citrine crystals
- V E Khadzhi
- G V Reshetova
V. E. Khadzhi, G. V. Reshetova, Method of producing citrine crystals,
US patent 4024013. http://www.freepatentsonline.com/4024013.
html [accessed 20 April 2011]
- P Vandenabeele
- K Castro
- M Hargreaves
- L Moens
- J M Madariaga
- H G M Edwards
P. Vandenabeele, K. Castro, M. Hargreaves, L. Moens, J. M. Madariaga,
H. G. M. Edwards, Anal. Chim. Acta 2007, 588, 108.
- C M Schmidt
- M S Walton
- K Trentelman
C. M. Schmidt, M. S. Walton, K. Trentelman, Anal. Chem. 2009,
81, 8513.
- D Bersani
- S Andò
- P Vignola
- G Moltifiori
- I G Marino
- P P Lottici
- V Diella
D. Bersani, S. Andò, P. Vignola, G. Moltifiori, I. G. Marino, P. P. Lottici,
V. Diella, Spectrochim. Acta A 2009, 73, 484.