Gemology

The origins and identities of the gem minerals known in antiquity have been construed primarily from ancient literary sources.  Some of the most important texts are not preserved in the translation of original manuscripts but are versions produced later, often several centuries later. They may survive only as fragmentary works or paraphrased in the works of other writers. Sometimes they survive in successive editions which bear accumulated errors and defects iterated over centuries. Some of the most significant works and problems of their handling in translation have been discussed. Attention has been devoted especially to lexical problems associated with trying to reconcile ancient and modern mineral taxonomies, inconsistent usage of gem terms, some of which are deprecated, and contemporary bias of translators.
Examination of approximately 1,100 objects representing the range of lapidary materials known to ancient gem cutters provided objective reference to consider some of the most troublesome gemstone identities and presumed gemstone origins that have come to be generally accepted as true. Empirical observations of the gems examined, archaeology, and the discovery of new gem sources in recent decades suggest that updated translations of some important treatises are needed, especially Books 36-37 of Pliny the Elder’s »Natural History«, which was published more than 50 years ago.
Most of the gems examined came from private or museum collections whose provenience dates between the 17th and 20th centuries. Lacking known archaeological context in most instances hinders tracing the mechanism of transmission or the path traveled between a raw lapidary material’s origin and its eventual deposition as a fashioned object in its date- and place-specific cultural setting.

Preface; History of the Collection; Abbreviations; General Introduction; The uses of Gems; The choice of designs on gems; The technique of gem engraving; The materials used for ancient gems; Appreciation and collecting of gems; Gem engravers and their signatures; Forgeries; Catalogue; I. Greek; II. Etruscan and Italic; III. Roman intaglios, first century b.c. to fourth cantury a.d.; IV. Hellenistic and Roman Cameos and Works in the round, second century b.c. to fourth century a.d.; Concordance of the numbers in the 1920 and the 1956 editions of the catalogue; General index; Index of inscriptions.

Statistical correlations in flowrate fluctuations between wells from many fields appear to bear out the expectation that the hydraulic conductivities of faults and fractures in reservoirs can be influenced by geomechanical perturbations due to production operations: the fluctuations are characterised by high correlations over very large separation distances between wells; and those correlations appear to be stress-related and fault-related. An entirely separate relationship derived from observations in multiple fields is a strong bias of directionalities shown by injected fluids towards the local orientation of modern-day major principal horizontal principal stress axis (S Hmax ). These two sets of independent field observations provide mutually supporting observational evidences for the general geomechanical sensitivity of faults and fractures. However, whilst peaks in flowrate correlations are observed at about 30 o to S Hmax , the preferred flooding directionalities are at smaller angles to S Hmax . A recently proposed machanism is able to explain the orientational relationships in both sets of data. It involves interacting, stress-aligned, compliant micro-cracks near a critical density; there is a large background of observations of shear-wave splitting in many types of formations that supports the prevalence of such micro-cracks. As a practical low-cost tool, analysis of flowrate correlations can provide valuable information about the major reservoir pathways as an adjunct to reservoir characterisation studies. This information can aid history-matching of reservoir models, particularly those involving fractures. The technique is also well-suited to monitoring reservoir behaviour in time-lapse fashion.

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

Shoreline and shelf-edge trajectories describe the migration through time of sedimentary systems, using geomorphological breaks-in-slope that are associated with key changes in depositional processes and products. Analysis of these trajectories provides a simple descriptive tool that complements and extends conventional sequence stratigraphic methods and models. Trajectory analysis offers four advantages over a sequence stratigraphic interpretation based on systems tracts: (1) each genetically related advance or retreat of a shoreline or shelf edge is viewed in the context of a continuously evolving depositional system, rather than as several discrete systems tracts; (2) subtle changes in depositional response (e.g. within systems tracts) can be identified and honoured; (3) trajectory analysis does not anticipate the succession of depositional events implied by systems-tract models; and (4) the descriptive emphasis of trajectory analysis does not involve any a priori assumptions about the type or nature of the mechanisms that drive sequence development. These four points allow the level of detail in a trajectory-based interpretation to be directly tailored to the available data, such that the interpretation may be qualitative or quantitative in two or three dimensions. Four classes of shoreline trajectory are recognized: ascending regressive, descending regressive, transgressive and stationary (i.e. nonmigratory). Ascending regressive and high-angle (accretionary) transgressive trajectories are associated with expanded facies belt thicknesses, the absence of laterally extensive erosional surfaces, and relatively high preservation of the shoreline depositional system. In contrast, descending regressive and low-angle (nonaccretionary) transgressive trajectories are associated with foreshortened and/or missing facies belts, the presence of laterally extensive erosional surfaces, and relatively low preservation of the shoreline depositional system. Stationary trajectories record shorelines positioned at a steeply sloping shelf edge, with accompanying bypass of sediment to the basin floor. Shelf-edge trajectories represent larger spatial and temporal scales than shoreline trajectories, and they can be subdivided into ascending, descending and stationary (i.e. nonmigratory) classes. Ascending trajectories are associated with a relatively large number and thickness of shoreline tongues (parasequences), the absence of laterally extensive erosional surfaces on the shelf, and relatively low sediment supply to the basin floor. Descending trajectories are associated with a few, thin shoreline tongues, the presence of laterally extensive erosional surfaces on the shelf, and high sediment supply to basin-floor fan systems. Stationary trajectories record near-total bypass of sediment across the shelf and mass transfer to the basin floor.

Egypt’s Red Sea island of Zabargad, also called St. John’s Island, is arguably the world’s most famous source of gem olivine, or peridot.  Both the island and its eponymous gemstone were called “topazos” by ancient writers.  Although much has been written about Zabargad’s unusual geology and modern mine workings, an ancient peridot mine had not been verified until a geo-archaeological expedition to the island in 2010 confirmed the existence of ancient mine workings and associated ruins of buildings and a water well.  In the first of two companion articles, the findings from this expedition are discussed in relation to literary references on the subject and the relationship between Zabargad and Berenike, the Ptolemaic-Roman port city on the Egyptian mainland opposite the island and a major emporium for the maritime trade with eastern Africa, the Persian Gulf and India.  Peridot was imported via this port-of-entry into the Graeco-Roman world, where it was used primarily for ring stones.  In the second article, the historiography of ancient literary sources on both the identity and geographic origins of the gem known today as peridot is examined with reference to the 2010 expedition to Zabargard and a survey of extant ancient engraved gems carved from peridot. Among other possible sources of peridot in antiquity is a second Red Sea island called “Cytis” by the Roman encyclopedist Pliny the Elder (d. AD 79). The association of Cytis with modern Kod Ali Island,  located a few kilometers off the coast of Eritrea, is also discussed.

The results of quantitative electron microprobe analyses and observations of gemmological properties and microscopic features are presented for 11 garnets of ancient Greek, Etruscan and Roman manufacture. In addition to chemical data, the gemmological properties of the Getty Museum garnets are presented, including refractive index, density and inclusions. According to their chemical composition and gemmological properties, the 11 garnets were subdivided into four groups: Cr-poor pyrope, Mn-rich almandine, Ca-rich almandine and intermediate pyrope-almandine. Combining the data of the 11 Getty garnets with published analyses of 26 Greek and Roman garnets from ancient jewellery and glyptic, the chemical distribution pattern of all 37 garnets expanded the boundaries of the established four groups and added a fifth garnet group comprising Mn-poor almandine. The compositional fields for these five groups are compared with data reported for Early Medieval garnets, mostly from Merovingian cloisonné jewellery. The chemical composition and physical properties of the garnets yield insights into possible sources of rough gem material, networks of trade/transmission in the ancient world, and associations between finished objects now dispersed in different collections.

Among the metal (gold and copper) and non-metal (minerals, rocks, pottery, pigments, bioobjects) artefacts in the Chalcolithic graves from Varna in Bulgaria are numerous beads of chalcedony (carnelian and agate) composition. To the three morphological types of beads already described (type 1 -elongated barrel-shaped; type 2 -elongated with trapezohedral facets; type 3 -short cylindrical; , a rare forth type -elongated cylindrical, has been added. Measurements of almost all the chalcedony beads have been performed including weight and size. Mean values of weight and size are given for beads of all the studied graves as well as for the whole necropolis. The detailed study confirmed the complex "constant" number of 32 facets among the morphological type 2 carnelian and agate beads (16x16 on both sides on the elongation of the bead; the form is a truncated 16-fold trapezohedron). This is considered as the earliest complex type of faceting on a hard mineral as quartz (chalcedony is 6.5-7 on the Mohs scale). The mean weight of the type 1-2 carnelian and related beads is 0.4 g (or 2 carats), in close correspondence to the mean value of the gold short cylindrical beads -thus a Chalcolithic weight unit has been introduced called van (from Varna necropolis) supposedly relating mineral and metal artefacts in an early weight system. The position in the graves and all the processes of manufacture (including tumbling) of the faceted chalcedony beads were shortly discussed as part of the archaeogemmological analysis.

Peter Paul Rubens is known to have collected gems as well as raw minerals. This chapter situates the artist's interest in stones in a wider historical context and argues for the influence on his painted oeuvre of his knowledge of cameos and gems. It concludes with an examination of the cameo bracelets in the Brueghel family portrait by the artist.

Nephrite-yielding prehistoric cultures in Europe have been using nephrite artifacts usually as axes or as ritual objects (including amulets). The nephrite artifacts are traced in largest number known from Maurach. For certain prehistoric sites, the source of nephrite is not yet known. Archaeomineralogical studies are suggested to be made in this respect for tracing prehistoric trade routes and nephrite outcrops. Nephrite occurrences in Europe are known and reported from (in alphabetical order)(European part of the Russian Federation), Spain, Switzerland, Turkey (Turkish Thrace) and Ukraine. Almost all of the nephrite occurrences are of the serpentinite metasomatic genetic type and only in a few cases -of the dolomitic marble genetic type (Val Malenco, Italy; Scortaseo, Switzerland). Rare secondary glacier-related type nephrite finds in the northern part of Europe are also reported.

Over the past two years, the heat treatment of corundum involving lattice diffusion of beryllium (Be) at temperatures over 1800°C has become a major issue in the gem trade. Although initially only orange to orangy pink ("padparadscha"-like) sapphires were seen, it is now known that a full range of corundum colors, including yellow and blue as well as ruby, have been produced or altered by this treatment. An extension of the current understanding of the causes of color in corundum is presented to help explain the color modifications induced by Be diffusion. Empirical support is provided by Bediffusion experiments conducted on corundum from various geographic sources. Examination of hundreds of rough and faceted Be-diffused sapphires revealed that standard gemological testing will identify many of these treated corundums, although in some instances costly chemical analysis by mass spectrometry is required. Potential new methods are being investigated to provide additional identification aids, as major laboratories develop special nomenclature for describing this treatment.

This study provides the first quantitative geochemical, petrological, and mineralogical data on major rock types and minerals in the Kafubu area. Highly magnesian talc-chlorite ± actinolite ± magnetite metabasites hosting emerald mineralization are identified as metamorphosed komatiites. These rocks contain 3000–4000 ppm Cr, and provided the amount of this element necessary for the crystallization of emeralds. Associated amphibolites of andesitic and basaltic-andesitic composition are low in chromium. The estimated equilibration temperatures during regional metamorphism, using am-phibole-plagioclase thermometry on several amphibolite samples, gave a narrow interval of 590–630 °C, assuming a pressure of 400–600 MPa. This metamorphic event pre-dates the emerald mineralization and the emplacement of pegmatite dikes. Emerald-bearing phlogopite schists are confined to the contacts of quartz-tourmaline veins and quartz-feldspar pegmatites with magnesian metabasites. The quartz-tourmaline ...

Greco-Roman culture classified a great variety of gems. Authors such as
Theophrastus, Plutarch and Pliny the Elder dealt with the subject. To now which gems were most highly valued in ancient Rome, it is essential to consult book 37 of Pliny the Elder. Book 37 of Pliny’s Natural History is one of the few accounts on precious stones, gems and amber that collects information from various sources of antiquity, which in many cases have survived only thanks to Pliny’s transcription. He catalogued the most prestigious gems, and discussed their origin, their exploitation techniques, their properties and their etymology. This corpus collects a total of 240 different variants of gems, of which, in 93 cases, its place of origin is known. In order to know to what extent the words of Pliny reflect the reality of the Roman market, we have analyzed as examples ten catalogs of modern collections of gems from various places and compared them with Pliny’s comments. This analysis confirms the fact that the urban Roman elites valued precious stones extracted from the territories beyond the Roman Empire, especially those of the East. The ten catalogues contain more than 4000 different gems and glasses. It compares the information in Pliny’s book on gems with ten current catalogs of various museums, adding more than 4000 analyzed copies. Both of these sources similar results and therefore confirms the interest of the Romans for these productions.

Studies of prehistoric (Neolithic to Chalcolithic period) artefacts from the territory of Bulgaria during the past decade revealed a lot of specific gem and decorative minerals and materials: nephrite, malachite, serpentinite, turquoise, jadeite, jet, carnelian, agate and jasper (including heliotrope). Nephrite artefacts in Bulgaria, as well as in some other countries on the Balkans, are widespread during the Neolithic and rare during the Chalcolithicthe nephrite sources are under discussion. A Balkan "nephrite culture" is introduced, which is supposed to be the earliest in the world, compared to the well known Chinese "nephrite cultures". The Varna Chalcolithic necropolis (middle of the V mill. BC) is known with the earliest and largest amount of gold artefacts in the world, including also some copper objects from the copper mines near Stara Zagora. A large amount of beads are also identified as made by malachite (in rare cases with azurite), serpentinite, carnelian, agate, coal (jet), marble and shells. Some of the carnelian beads from Varna display 16+16 facets along their elongation, which is the first record for a constant and complex faceting of hard mineral known so far. An early prehistoric weight system links mineral beads and gold artefacts (the weight unit "van" is introduced, 0.4 g = 2 carats). The first report of turquoise beads for SE Europe is related to the Orlovo prehistoric site (Haskovo district). The "Thracian stone" in ancient sources is identified also as heliotrope, which is known since the Chalcolithic in the Eastern Rhodopes. Some of the artefacts are masterpieces of art and as stage of perfection, thus pointing to the Balkans as a cradle of prehistoric gemmology.

For about three decades, airborne electromagnetic (AEM) systems have been used for groundwater exploration purposes. Airborne systems are appropriate for large-scale and efficient groundwater surveying. Due to the dependency of the electrical conductivity on both the clay content of the host material and the mineralization of the water, electromagnetic systems are suitable for providing information about the aquifer structures and water quality, respectively.

This paper compares the resolution and efficiency of 2D resistivity imaging survey with eight electrode arrays by numerical simulations. The arrays analysed include the pole-pole (PP), pole-dipole (PD), pole-bipole (PB), Wenner-α (WN), Schlumberger (SC), dipole-dipole (DD), Wenner-β (WB), γ-array (GM), gradient (GD) and midpoint-potential-referred measurements (MPR) arrays. Five synthetic geological models that simulate a buried channel, narrow conductive dyke, narrow resistive dyke, dipping blocks and covered waste ponds were used to examine the surveying efficiency (anomaly effects, signal-noise ratios) and the imaging capabilities of these arrays. Also, the response to variations in data density and noise sensitivities of these electrode configurations were investigated using the robust inversion and smoothness-constrained least-squares ( 2 L -norm) inversion for the five synthetic models. The results show that: (1) GM and WN have less noise contamination than other electrode arrays;

Archaeomineralogy (archaeological mineralogy, mineralogical archaeology) is an interdisciplinary science related to the study of archaeological and historical objects of a mineral and rock composition (Kostov, 2007a; Rapp, 2009). In certain cases, the achaeomineralogy is linked also to archaeogemmology as a science for the study of natural and artificial raw materials which have been used for jewellery or other decorative purposes since the dawn of humankind to modern times, to ancient numismatics as part of archaeometallurgy which studies ores, slags and alloys, to petroarchaeology which studies different rock artifacts and pottery. Archaeomineralogy can be regarded as a major part of geoarchaeology as a broader scientific field of application of all the different branches of Earth sciences during searching, prospecting and study of archaeological monuments or single artifacts. It is also a part of archaeometry as a much broader field of interdisciplinary studies in archaeology (Kuleff, 2012). As priorities for Bulgaria are considered some Paleolithic and Neolithic sites, the Varna Chalcolithic necropolis, megalithic and rock-cut sites, the Thracian Culture, as well as artifacts related to the Ancient Bulgarians in all the areas of their settlement throughout the centuries.

Aus den frühbronzezeitlichen Schichten von Troia, hauptsächlich aus den Phasen II Spät (ca. 2350-2250 v. Chr.) und III (ca. 2250-2200/2150 v. Chr.) stammen bekanntlich zahlreiche Objekte aus Edelmetall und Halbedelstein. Mehrere Forscher haben darauf aufmerksam gemacht, dass viele der Goldfunde aus Schliemanns Schätzen, aber auch einige aus den Siedlungsschichten, Halbprodukte sind, und man daraus auf eine beachtliche Goldschmiedeproduktion in Troia schließen kann. Im Gegensatz dazu wurden Gegenstände aus Stein, wie Bergkristall, Karneol, Hämatite oder Jade, bisher kaum aus dieser Perspektive betrachtet. In diesem Beitrag werden die Hinweise auf lokale Goldschmiede zusammengefasst und ergänzt sowie die Evidenz für das Schleifen von harten Steinsorten zum ersten Mal dargelegt. Nicht nur komplizierte metallurgische Verfahren wie die Granulation und das Aufbringen von Filigran mit Reaktionslot, sondern auch das Schleifen mit dem Metallbohrer und Schleifmittel sind belegt.

The Preslav gold treasure (adornments from gold decorated with enamel, beads of gem minerals and pearls: diadem, bilateral necklace, medallions, several earrings and earcaps, rings, buttons, appliqués and other small finds) was found in 1978 near the town of Veliki Preslav -the second Bulgarian capital during the еnd of the First Bulgarian Kingdom. The treasure (X century) belonged to a female member of the royal family and is suggested to be of a Byzantine origin. A morphometric study and gem testing was made on all the gemmological materials -minerals and numerous pearls. Among the gem minerals are identified 40 emeralds, 12 violet sapphires, 10 reddish violet garnets, 5 rock crystals, 3 amethysts and 1 carnelian. Their inclusions and type of cut are listed. The average dimensions for the emerald polished and rounded on the edges prisms from two medallions are: length 0.48 cm and width 0.59 cm. The average dimensions for the mainly barrel shaped sea pearls from a gold medallion are length 0.40 cm and diameter 0.45 cm. The origin of the emeralds is under discussion, and they are compared with other emerald finds in Europe, including from Bulgaria, from the Antiquity and Early Medieval Period. As a probable source for the gem minerals (emerald, sapphire, garnet), according to their inclusions, is suggested an Eastern (India and Sri Lanka) origin (alternative for the emeralds -the Hindou-Kush area), and the pearls are probably from the Indian Ocean of the Persian Gulf.

The Preslav gold treasure (adornments from gold decorated with enamel, beads of gem minerals and pearls: diadem, bilateral necklace, medallions, several earrings and earcaps, rings, buttons, appliqués and other small finds) was found in 1978 near the town of Veliki Preslav -the second Bulgarian capital during the еnd of the First Bulgarian Kingdom. The treasure (X century) belonged to a female member of the royal family and is suggested to be of a Byzantine origin. A morphometric study and gem testing was made on all the gemmological materials -minerals and numerous pearls. Among the gem minerals are identified 40 emeralds, 12 violet sapphires, 10 reddish violet garnets, 5 rock crystals, 3 amethysts and 1 carnelian. Their inclusions and type of cut are listed. The average dimensions for the emerald polished and rounded on the edges prisms from two medallions are: length 0.48 cm and width 0.59 cm. The average dimensions for the mainly barrel shaped sea pearls from a gold medallion are length 0.40 cm and diameter 0.45 cm. The origin of the emeralds is under discussion, and they are compared with other emerald finds in Europe, including from Bulgaria, from the Antiquity and Early Medieval Period. As a probable source for the gem minerals (emerald, sapphire, garnet), according to their inclusions, is suggested an Eastern (India and Sri Lanka) origin (alternative for the emeralds -the Hindou-Kush area), and the pearls are probably from the Indian Ocean of the Persian Gulf.

Turquoise in the Life of American Indians.
The mankind has known turquoise for more than ten thousand years. This is the only “live” mineral which can change its color with weather changes and the condition of its owner. Probably it is one of the reasons why it has always been surrounded by so many legends and superstitions in most cultures of the world. Turquoise was already mentioned in the first works about minerals and in a number of myths, especially those of the Navajo Indians of the U.S. South-West. In all continents it has been considered the happiest semi-precious stone which has taken a unique place in the history of civilizations and is still used in a great number of spheres of human activity.
The paper describes its major mineral qualities, deposits, the origins of its name, the most important and the oldest turquoise objects found during archeological digs, the use of turquoise in different countries and times, the legends about it, its role in different mythologies, traditional jewelry techniques of several North American Indian tribes, the varieties of the mineral and its imitations. A special emphasis is laid on the use of turquoise and the beliefs associated with it in American Indian cultures.
A Navajo myth about the goddess called Changing Woman (or Turquoise Woman) is studied separately as an explanation of a special attitude of American Indians to that stone and its very important role in their life up to the present day.

The Permian Ecca Group of the Karoo Basin, South Africa preserves an extensive well-exposed siliciclastic basin £oor, slope and shelf-edge delta succession.The Kookfontein Formation includes multiple sedimentary cycles that display clinoform geometries and are interpreted to represent the deposits of a slope to shelf succession.The succession exhibits progradational followed by aggradational stacking of deltaic cycles that is related to a change in shelf-edge trajectory, and lies within two depositional sequences. Sediment was transferred to the slope via overextension of deltas onto and over the shelf edge, resulting in failure and re-adjustment of local slope gradients.The depositional facies and architecture of the Kookfontein Formation record the change from a bypassto accretion-dominated margin, which is interpreted to re£ect a decrease in sediment transport e⁄ciency as the slope gradient decreased, slope length increased and shelf-edge trajectory rose. During this time the delivery system changed from point-sourced basin-£oor fans fed by slope channels to starved basin-£oor with sand-rich slope clinoforms.This is an example of a progradational margin in which the younger slope system is interpreted to be of a di¡erent style to the older slope system that fed the underlying sand-rich basin £oor fans.

Tourmaline typically forms where crustal rocks interact with migrating hydrous fluids or silicate melts, and its isotopic composition provides a reliable record of the isotopic composition of the fluids and melts from which it crystallized. Minerals of the tourmaline supergroup are exceptional in their physical robustness and chemical variability, and they allow us to extract a uniquely broad range of isotopic information from a single mineral. The chemical variability of tourmaline confronts us with the difficulty of deciphering an extremely complex mineral system, but it also presents us with a geochemical recorder of half the periodic table, a breadth of representation that is unparalleled among minerals. Plate tectonic–scale geochemical cycles, local and regional fl uid–rock interactions, magmatic–hydrothermal systems, ore-forming processes, and ages of tourmaline formation have all been reconstructed using this unique isotopic broadband recorder.

About 240 natural and man-made gemstone glyptics (artefacts) (seal gemstones and ceremonial stones)
and jewelleries with gemstones in the I˙zmir Archaeological Museum belong to the Anatolian cavitations
regarding to the Greco-Persian, Roman, and elder periods. Many of these glyptics are loose gemstone
parts, the others were mainly mounted a ring or assembled into various jewellery parts, such as, pendants,
necklaces, earrings, and bracelets. These artefacts are identified using non-destructive and non-invasive
gemmological investigation methods (hydrostatic balance, refractometre, gemmology microscope, and
UV lamb). It is revealed that a total of 108 of these glyptics are collected into the natural gemstone groups.
With being revealed the periods and features to be cut and polished of the ancient gemstone artefacts,
the dating and estimating the values of the jewelleries with gemstones which are both obtained in the
archaeological excavations and come to the museum for giving can be possible. In addition, this study
shows that the conservation process of the ancient gemstones and jewelleries with gemstones, when it
is not considered the gemmological features of them, results to be a mistake in the evaluation of many
objects.

A review of the genetic classifications of jasper based on mineralogical data outlines three main types of jasper and related rocks: 1 -jaspers; 2 -jasperoids; 3 -jasper-like rocks. True jasper has a quartz composition and is of metamorphic or metasomatic origin. Related in different colour and density to jasper other rocks of sedimentary or igneous origin can be found usually having a dominantly chalcedony-quartz and feldspar-quartz composition (jasperoids and jasper-like rocks). Main mineral impurities which cause the colour of the described rocks are listed.

This paper addresses the cultural translation of some exotica – selected valuable objects that were brought from the south Aegean or even more distant areas to Troy, Beşik-Tepe and Greek Macedonia mainly during the Late Bronze Age. The discussion will focus on jewellery and seals made of carnelian, steatite and bone. Such foreign goods, often labelled as imports, are usually objects with complicated histories. These histories began with acquisition, then went through various forms of ownership and display, and finally ended with release, all while simultaneously undergoing a process of domestication and 'de-exotification'. Release, especially an intentional release such as in the case of burial goods, treasures and cult deposits, is discussed comprehensively since these are the best-documented cases of interaction between things and people in the area of the north Aegean. Also discussed is the phenomenon of copying as a complicated procedure of appropriation, as well as the case of rejection of ornaments and symbolism.

What has natural history done for physics? The eighteenth century is an important source of answers to this question, since it witnessed the emergence of experimental physics and systematic natural history as distinct branches of science. Much existing literature suggests that these two traditions were opposed in the eighteenth century or that they rarely made contact. The main aim of this dissertation is to show that natural history made an important contribution to the experimental method of the French scientist Charles-François de Cisternay Dufay (1698–1739). This contribution took the form of systematic experimental history. To do systematic experimental history is to apply the same experimental operation to a large number of animal, plant or mineral species, with the aim of comparing the outcomes of these trials. An analysis of Dufay’s articles and correspondence shows that he possessed a large gem collection and that he was in contact with some of the most prolific collectors of his day. His systematic experimental history of gems informed his pioneering papers on electricity, luminescence and double refraction. In this form natural history helped him to discover new phenomena, generalise known phenomena, optimise known phenomena, and discern taxonomic rules, ie. rules expressing contrasts between the observable behaviour of different kinds of material. Dufay’s rules about the electrical behaviour of conductors and non-conductors are of particular interest. These rules were the basis for an absorption theory of electrics that sheds new light on Dufay’s electrical research and on that of his immediate French successors. These reinterpretations of Dufay’s experimental papers are supported by two further claims. The first is that there was a continuous tradition of systematic experimental history at the Académie Royale des sciences in the seventy years before Dufay began his electrical research. The second is that Dufay’s relationship with René Réaumur, the leading naturalist in France at the time, was richer than historians have supposed. This study opens up new lines of research on the role of materials in the qualitative physics of the eighteenth century, the role of naturalists in the quantification of physics around 1800, and the interaction between physics and mineralogy at the Jardin du Roi and, in the nineteenth century, at the Muséum national d’histoire naturelle.

Sur plusieurs sceaux grecs d’époque classique, un héron est représenté en compagnie d’une femme. L’objectif de cet article est ainsi de fournir des éléments pour essayer de clarifier la signification de ce motif. Pour cela, il convient de tenir compte des motifs sur les matrices grecques présentant des hérons avec ou sans des personnages de femmes, mais aussi de l’iconographie des vases grecs des VIe-IVe siècles. Certains spécialistes ont perçu cet animal comme un marqueur permettant de reconnaître les appartements des femmes et en ont ainsi fait un attribut genré : l’oiseau construirait une différence entre espaces dévolus aux femmes et aux hommes. Néanmoins, les images des vases et des sceaux laissent percevoir la place du héron dans la figuration des échanges érotiques et des pratiques hétérosexuelles. Le héron illustre donc surtout les rapports des hommes et des femmes entre eux.

On several classical Greek seals, herons are represented alongside women. The aim of this text is to provide elements of explanation in order to clarify the meaning of this motif. For that purpose, we have to take into account the devices on the Greek seals showing herons with or without women, but also the Greek vase-painting of the sixth-fourth centuries BC. Some specialists saw this animal as a sign allowing everyone to recognize the women’s apartments and, thus, turned it into a gendered attribute: the bird would develop a difference between spaces allotted either to women or to men. However, the images on vases and seals suggest that the heron is a part of the figuration of erotic exchanges and heterosexual practices. Therefore, the heron rather denotes the interactions that men and women bind together.

According to recent mineralogical determinations of prehistoric (Neolithic and Eneolithic) artefacts from Bulgarian museums a lot of nephrite objects have been identified (mainly represented by small axes and chisels, ritual scepter and zoomorphic amulets as well as some decorations). Their distribution on the territory of Bulgaria has been traced, together with data on some neighboring countries on the Balkans and in other European regions. A description has been made of the colour varieties, microscopic features and the possible methods of working of some of the nephrite artefacts. The lack of up to now known nephrite occurrences on the Balkans puts the question about the origin of nephrite and the more detailed study of places with ultrabasic rocks. Because of the large number of nephrite objects found, which have been aged since the Early Neolithic, as well as of their significance in the history of human civilization, a Balkan "nephrite culture" has been introduced, which is considered earlier in time (VII-VI mill. BC) in respect to the well known Neolithic "nephrite cultures" in China (Hemudu, Hongshan, Liangzhu, Longshan) and the Russian Federation (Kitoi, Glaskovo).

Vp-Vs relations play a key role in lithology and pore fluid prediction from both sonic and seismic data. Shear wave velocities are required as input to AVO modelling and analysis and for standard fluid substitution using Gassmann equation. Shear waves are almost unaffected by pore fluid changes, as opposed to compressional waves. Hence, Vp-Vs relations are useful fluid indicators. Furthermore, Vp-Vs relations will be diagnostic of lithology and cement volume since different lithologies and amount of cements will have different trends in the Vp versus Vs plane.

Euler deconvolution and the analytic signal are both used for semi-automatic interpretation of magnetic data. They are used mostly to delineate contacts and obtain rapid source depth estimates. For Euler deconvolution, the quality of the depth estimation depends mainly on the choice of the proper structural index, which is a function of the geometry of the causative bodies. Euler deconvolution applies only to functions that are homogeneous. This is the case for the magnetic field due to contacts, thin dikes and poles. Fortunately, many complex geological structures can be approximated by these simple geometries. In practice, the Euler equation is also solved for a background regional field. For the analytic signal, the model used is generally a contact, although other models, such as a thin dike, can be considered. It can be shown that if a function is homogeneous, its analytic signal is also homogeneous. Deconvolution of the analytic signal is then equivalent to Euler deconvolution of the magnetic field with a background field. However, computation of the analytic signal effectively removes the background field from the data. Consequently, it is possible to solve for both the source location and structural index. Once these parameters are determined, the local dip and the susceptibility contrast can be determined from relationships between the analytic signal and the orthogonal gradients of the magnetic field. The major advantage of this technique is that it allows the automatic identification of the type of source. Implementation of this approach is demonstrated for recent high-resolution survey data from an Archean granite-greenstone terrane in northern Ontario, Canada.