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Mat ic dyke is a sign of regional extension, and thus has important tectonic significance. A great amount of mafic dykes occur in the Kongling terrain of the Yangtze Craton, which have great bearing on the early evolution of the Yangtze Craton. Their ages, however, have not been well constrained. In this paper we report an integrated study of zircon U-Pb age and Hf isotope compositions for a mafic dyke in the Kongling terrain. The zircons yielded a weighted mean 207Pb/206Pb age of 1852±11Ma, which represents its intrusion age. They have ϵHf(∫) values of -6.3 to 0.5, with a weighted mean of -3.06±0.88, suggesting that the mat ic dyke came from metasomatic mantle. The results indicate that the Yangtze Block had transformed into post-collisional extensional regime at Ca. 1850 Ma. In the same period, the Yangtze Craton shows enough rigidity to produce brittle rupture, and thus has the characteristics of a craton. [ABSTRACT FROM AUTHOR]

This paper reports on the results of investigations into the transformation of the corundum structure upon reducing annealing at high temperatures in the range from 1700 to 2050°C. It is established that the reduction results in the transformation of corundum into new phases with a lower oxygen content, including the phase with a spinel structure. These structures are assumed to be stabilized by anion vacancies. A model of the crystal structure of the spinel phase is proposed. This model provides an adequate description of the compound obtained in the experiment. [ABSTRACT FROM AUTHOR]

Gemstones are minerals of gem qualities used for adornment and decoration with the attributes of beauty, durability and rarity. Traditionally, although China has been regarded as the most important source for nephrite, over the past decades, a large variety of gemstone resources have been newly discovered in China owing to continuous exploration works. The vast land with various geological and geochemical backgrounds is rich in gemstone resources with potential for new deposits discoveries. In pegmatites, gemstones are related to granitic magma events and mainly occur in pegmatitic cavities, such as tourmaline, aquamarine, spodumene, spessartine, moonstone, quartz, apatite, and topaz. The eruption of Tertiary basaltic magma provides gem-quality sapphire, spinel, olivine, garnet, and zircon. The supergene oxidation zones of some copper and iron deposits in Hubei and Anhui province host gem-quality turquoise and malachite. Moreover, the formation of the nephrite deposit in China is mostly related to the carbonatite and serpentinite rocks involved in the metamorphic-metasomatic processes. This paper comprehensively introduces the distribution of gemstones deposits, as well as the gemological and mineralogical characteristics of gemstones in China. Our present investigation provides insights into the gemstone potential of China for further exploitation. [ABSTRACT FROM AUTHOR]

Middle Neoproterozoic igneous rocks are widespread in South China, but their petrogenesis and tectonic implications are still highly controversial. The Guangfeng middle Neoproterozoic volcani-sedimentary succession was developed on a rare Sibaoan metamorphic basement (the Tianli Schists) in the southeastern Yangtze Block, South China. This paper reports geochronological, geochemical and Nd isotopic data for the volcanic rocks in this succession. The volcanic rocks consist of alkaline basalts, andesites and peraluminous rhyolites. SHRIMP U-Pb zircon age determinations indicate that they were erupted at 827 ± 14 Ma, coeval with a widespread episode of anorogenic magmatism in South China. Despite showing Nb-Ta depletion relative to La and Th, the alkaline basalts are characterized by highly positive ϵNd(T) values (+3.1 to +6.0), relatively high TiO2 and Nb contents and high Zr/Y and super-chondritic Nb/Ta ratios, suggesting their derivation from a slab melt-metasomatized subcontinental lithospheric mantle source in an intracontinental rifling setting. The andesites have significantly negative ϵNd(T) values (-9.3 to -11.1) and a wide range of SiO2 contents (57.6-65.6 %). They were likely generated by the mixing of fractionated basaltic melts with felsic melts derived from the Archaean metasedimentary rocks in the middle to lower crust. The rhyolites are highly siliceous and peraluminous. They are characterized by depletion in Nb, Ta, Sr, P and Ti and relatively high ϵNd(T) values (-3.0 to -4.8), broadly similar to those of the adjacent c. 820 Ma peraluminous granitoids derived from the Mesoproterozoic to earliest Neoproterozoic sedimentary source at relatively shallow levels. We conclude that the Guangfeng volcanic suite is a magmatic response of variant levels of continental lithosphere (including lithospheric mantle and the lower-middle to upper crust) to the middle Neoproterozoic intracontinental rifling possibly caused by mantle plume activity. [ABSTRACT FROM AUTHOR]

This paper evaluates the analytical precision, accuracy and long-term reliability of the U-Pb age data obtained using inductively coupled plasma–mass spectrometry (ICP-MS) with a frequency quintupled Nd-YAG (λ = 213nm) laser ablation system. The U-Pb age data for seven standard zircons of various ages, from 28 Ma to 2400 Ma (FCT, SL13, 91500, AS3, FC1, QGNG and PMA7) were obtained with an ablation pit size of 30 μm diameter. For 207Pb/206Pb ratio measurement, the mean isotopic ratio obtained on National Institute of Standards and Technology (NIST) SRM610 over 4 months was 0.9105 ± 0.0014 ( n = 280, 95% confidence), which agrees well with the published value of 0.9096. The time-profile of Pb/U ratios during single spot ablation showed no significant difference in shape from NIST SRM610 and 91500 zircon standards. These results encouraged the use of the glass standard as a calibration standard for the Pb/U ratio determination for zircons with shorter wavelength (λ = 213 nm) laser ablation. But 206Pb/238U and 207Pb/235U ages obtained by this method for seven zircon standards are systematically younger than the published U-Pb ages obtained by both isotope dilution–thermal ionization mass spectrometry (ID-TIMS) and sensitive high-resolution ion-microprobe (SHRIMP). Greater discrepancies (3–4% younger ages) were found for the 206Pb/238U ages for SL13, AS3 and 91500 zircons. The origin of the differences could be heterogeneity in Pb/U ratio on SRM610 between the different disks, but a matrix effect accuracy either in the ICP ion source or in the ablation-transport processes of the sample aerosols cannot be neglected. When the 206Pb/238U (= 0.2302) newly defined in the present study is used, the measured 206Pb/238U and 207Pb/235U ages for the seven zircon standards are in good agreement with those from ID-TIMS and SHRIMP within ±2%. This suggests that SRM610 glass standard is suitable for ICP-MS with laser ablation sampling (LA-ICP-MS) zircon analysis, but it is necessary to determine the correction factor for 206Pb/238U by measuring several zircon standards in individual laboratories. [ABSTRACT FROM AUTHOR]

Bluish green staining in domestic fixtures was observed in three to 9-year-old houses in the city of Talca, located 256 km. south of Santiago, the capital of Chile. The houses contained copper pipes which were exposed to soft well water, with low pH and low buffer capacity. The aim of this paper is to establish the chemical composition of the stains and to determine the conditions by which they were formed. X-ray diffraction analysis of the stains revealed the presence of malachite, a copper compound that caused green coloring in kettles and water boilers. Dioptase, which is deep green in coloring, was identified in a bathtub tile. In one house, where blue stains were found in a toilet bowl, the presence of chrysocolla was suggested by means of X-ray fluorescence. In the field conditions studied it was concluded that the bluish green stains in bathroom home appliances were generated by the precipitation of copper compounds in places were leakages occur. [ABSTRACT FROM AUTHOR]

Abstract: Anticorrosion pigments were synthesized by reaction of metal aluminum lamellar particles whose surface is oxidized to Al2O3 during the first stage and by subsequent reaction with ZnO and/or MgO at 800–1150°C producing a thin spinel layer that is chemically bonded to the metal core of the pigment particles. Core–shell spinels were synthesized: MgAl2O4/Al; Mg0.8Zn0.2Al2O4/Al; Mg0.6Zn0.4Al2O4/Al; Mg0.4Zn0.6Al2O4/Al; Mg0.2Zn0.8Al2O4/Al; and ZnAl2O4/Al. The prepared pigments were characterized by means of X-ray diffraction analysis and scanning electron microscopy. The synthesized anticorrosion pigments were used to prepare epoxy coatings that were tested upon application for their physical–mechanical properties, anticorrosion properties and resistance against a chemical environment. All of the synthesized pigments exhibit good anticorrosion efficiency in epoxy coatings. Compared to lamellar kaolin and metal core of aluminum without coverage, the protective function of the synthesized pigments in coatings is demonstrably better. [Copyright &y& Elsevier]

The main objectives of the paper are numeric calculations of retention of diamond particle in metallic-diamond segments of circular saws. The segments are produced by means of the technology of powder metallurgy. The analysis has been preformed for cobalt, cobalt-iron and cobalt-tungsten sinters. The effective use of diamond impregnated tools is strongly depended on the retentive properties of the metal matrix, which must hold diamond grits firmly. Due to mismatch between thermal expansion coefficients of the matrix and diamond, the mechanical fields are generated in the matrix at diamond surroundings. The fields play a major role for retentive properties of matrix. It has been postulated that the potential retentive capability of a matrix can be associated with the amount of elastic and plastic deformation energy which occurs in the matrix around diamond particles. [ABSTRACT FROM AUTHOR]

Abstract  The present paper reports a study about how the uncertainties on some fundamental thermodynamic and structural quantities (formation enthalpy, specific heat, thermo-elastic properties, occupancy factors) propagate and affect the Gibbs energy calculated at given pressure and temperature conditions [G(P,T)] for mineral phases. A particular attention is paid to the role played by the uncertainties on the bulk modulus, its first derivative versus pressure, molar volume at a reference condition, i.e. V 0, and occupancy factors. The calculations in question are carried out for three phases: 2M 1-phengite, olivine and MgAl-spinel, in order to provide coverage for thermo-elastic parameters values common in a variety of natural processes. Above a few GPa, the uncertainty due to the deformation energy, i.e. σ[ΔG deform], and dependent on the parameters governing the equation of state, grows the dominant contribution to the total uncertainty on G(P,T), i.e. σ[G(P,T)]. σ[ΔG deform] is very sensitive to V 0, but the comparatively small σ(V 0)/V 0 value makes the V 0-contribution to σ[ΔG deform] less relevant than those due to the elastic parameters. The stability curve of 3T- versus 2M 1-phengite as a function of pressure (Curetti et al. in Phys Chem Mineral 32:670–678, 2006) is here revised in the light of the uncertainty on G(P,T): an improvement of accuracy such as to reduce the uncertainty on bulk modulus and its first derivative versus pressure by a 0.05 factor is, in principle, required to guarantee a fully unambiguous description of the relative stability between these two phases. [ABSTRACT FROM AUTHOR]

Sedimentary strata in the Lhasa terrane of southern Tibet record a long but poorly constrained history of basin formation and inversion. To investigate these events, we sampled Palaeozoic and Mesozoic sedimentary rocks in the Lhasa terrane for detrital zircon uranium–lead (U–Pb) analysis. The >700 detrital zircon U–Pb ages reported in this paper provide the first significant detrital zircon data set from the Lhasa terrane and shed new light on the tectonic and depositional history of the region. Collectively, the dominant detrital zircon age populations within these rocks are 100–150, 500–600 and 1000–1400 Ma. Sedimentary strata near Nam Co in central Lhasa are mapped as Lower Cretaceous but detrital zircons with ages younger than 400 Ma are conspicuously absent. The detrital zircon age distribution and other sedimentological evidence suggest that these strata are likely Carboniferous in age, which requires the existence of a previously unrecognized fault or unconformity. Lower Jurassic strata exposed within the Bangong suture between the Lhasa and Qiangtang terranes contain populations of detrital zircons with ages between 200 and 500 Ma and 1700 and 2000 Ma. These populations differ from the detrital zircon ages of samples collected in the Lhasa terrane and suggest a unique source area. The Upper Cretaceous Takena Formation contains zircon populations with ages between 100 and 160 Ma, 500 and 600 Ma and 1000 and 1400 Ma. Detrital zircon ages from these strata suggest that several distinct fluvial systems occupied the southern portion of the Lhasa terrane during the Late Cretaceous and that deposition in the basin ceased before 70 Ma. Carboniferous strata exposed within the Lhasa terrane likely served as source rocks for sediments deposited during Cretaceous time. Similarities between the lithologies and detrital zircon age-probability plots of Carboniferous rocks in the Lhasa and Qiangtang terranes and Tethyan strata in the Himalaya suggest that these areas were located proximal to one another within Gondwanaland. U–Pb ages of detrital zircons from our samples and differences between the geographic distribution of igneous rocks within the Tibetan plateau suggest that it is possible to discriminate a southern vs. northern provenance signature using detrital zircon age populations. [ABSTRACT FROM AUTHOR]

In this paper, a technique is proposed for the rendering of transparent objects interactively using the method of refractive rendering. In the proposed technique, the refractive rendering algorithm is performed in two stages, namely the pre-computation stage and the shading stage. In the pre-computation stage, ray-traced information, including directions and positions of rays, are generated by a ray tracing process and are stored in a set of ray lists. In the shading stage, these data are retrieved from the ray lists for computing the shading of an object. Using the proposed technique, photorealistic image of transparent objects and gemstones with various cuttings, material properties, lighting and background can be rendered interactively. By combining the refractive rendering technique with conventional shading techniques, jewelry and crystal designs can be rendered at a much higher speed comparing with conventional ray tracing techniques. [ABSTRACT FROM AUTHOR]

The liquidus temperature of spinel (AB2O4) crystals frequently limits the waste loading of vitrified nuclear waste. In other studies, glass structure-spinel liquidus temperature relationships were discovered for the non-spinel forming cations in glass, but no such relationship was identified for the spinel-forming metal-ions. In this paper, coefficients from an empirical first order mixture model describing spinel liquidus temperature were correlated with the octahedral site preference energy (OSPE) of the spinel-forming metal ions. The OSPE was calculated using approximations of glass and spinel structure made by extrapolating from data on similar glasses and spinels. A literature review indicated that Cr(III), Ni(II), and Fe(II) are most likely to be in the octahedral sites in spinel, Mn(II) in the tetrahedral site, and that Fe(III) will be common in both sites. These assignments were used as starting assumptions to calculate the OPSE for each metal ion. A strong correlation between the OSPE and the liquidus temperature coefficients of spinel-forming metal ions was observed. Further correlations determined that the Crystal Field Stabilization Energy was the most important portion of the OSPE for these spinels. These results indicate that the thermodynamic properties of spinel could be predicted based on assumptions of spinel structure, underpinned by fundamental properties, when scaled empirically. [ABSTRACT FROM AUTHOR]

In this paper, we propose that the “anomalous” optical response exhibited by GaP and InP infiltrated opals is due to the peculiar morphology shown by these materials when grown within the pores. In order to account for their optical response, we propose a new structural model consisting of a network of high dielectric spheres located in the pores of the bare opal, interconnected by cylinders of the same material. A fair agreement between the theoretical predictions using this model and the experimental measurements has been found. We also show that the inverse structure presents very interesting optical properties. [ABSTRACT FROM AUTHOR]

This paper describes corundum formation in a metasomatic reaction zonation around an ultramafic body within a metapelitic sequence. The investigated body is about 100 m in diameter and is located in the Saualpe of the Austroalpine nappe complex in the Eastern Alps. The body is surrounded by a 10 m wide reaction zone (here called zone 3) containing the paragenesis garnet-staurolite-biotite-margarite-chlorite-corundum. Beyond a further metasomatic transition zone (here called zone 2), there are undisturbed metapelitic host rocks (zone 1) that have the metamorphic peak paragenesis garnet-biotite-plagioclase-staurolite-muscovite-quartz. It is shown that reaction zonation formed around 7.2?kbar and 615?°C during regional metamorphism, just above the serpentine breakdown reactions in the system MgO-SiO2-H2O. Detailed analysis of the whole rock compositions shows that the reaction zonation formed by infiltration metasomatism that caused significant mass loss in the two alteration zones. These zones are particularly depleted in SiO2, Na2O and possibly K2O. AnXNa2O-XSiO2 thermodynamic pseudosection is presented that includes the parageneses of both the unaltered metapelitic host rock and the corundum-bearing parageneses. This suggests that the metasomatic process can be explained by the transfer of SiO2 and Na2O alone. We interpret that the process is driven by water liberated from the previously serpentinised ultramafic body during prograde dehydration during regional Eo-Alpine metamorphism. This fluid flowed outwards from the ultramafic body depleting the surrounding pelites in silica and causing margarite formation from plagioclase and muscovite. This interpretation of the driving mechanism is consistent with our knowledge of the low water activities of the Saualpe during the Eo-Alpine orogenic cycle. [ABSTRACT FROM AUTHOR]

Monazite dating is an important technique in geochronological studies. However, monazite U-Pb dating by SHRIMP is much less popular than zircon in geochronological applications. This paper compares the results of SHRIMP U-Pb dating of monazites and zircons separated from two granite samples, indicating that monazite SHRIMP U-Pb dating at the Beijing SHRIMP Centre is feasible and provides identical results within error. [ABSTRACT FROM AUTHOR]

The retrograded eclogites have been discovered in the middle part of the northern margin of the North China Craton, which occur as lens or boudin within biotite-plagioclase gneisses in Paleoproterozoic Hongqiyingzi Group. The peak eclogite facies (P > 1.40-1.50 GPa, T = 680 -730°C) mineral assemblage is composed of garnet, omphacite and rutile (±quartz), which was overprinted by the granulite facies mineral assemblage of vermicular symplectite of sodic clinopyroxene and plagioclase which replaced the precursory omphacite, and then amphibolite facies retrograded minerals with characterization of Amp+Pl kelyphitic rim and symplectite, and amphibole replaced clinopyroxene. The protolith of retrograded eclogites is oceanic basalt formed at 438 ± 11 Ma. The peak eclogite facies metamorphic age of the retrograded eclogite is 325 ± 4 Ma. These relict eclogites may be formed by the subduction of Paleo-Asian oceanic crust beneath the North China Craton during Late Paleozoic. The discovery of relict eclogite in this paper provides a new insight into farther understanding of tectonic evolution of the northern margin of the North China Craton, and the relationship between the Paleo-Asian Ocean and the North China Craton. [ABSTRACT FROM AUTHOR]

This paper considers the influence of light fluxes in the 200–600‐nm spectral range on the thermally stimulated luminescence (TL) of TLD‐500 radiation detectors based on anion‐defective corundum crystals. It has been shown that the luminescent‐storing action of light in the above spectral range is due to the optical ionization of F‐centers and electronic trapping centers of carriers responsible for the dosimetric peak at 450 K and TL at higher temperatures. The features of the dosimetric information distortion depending on the initial state of population of deep traps and the spectral composition and power of optical radiation are discussed. [ABSTRACT FROM AUTHOR]

The paper presents the applicability of oxyreactive thermal analysis (OTA) for the investigation of different kinds of resins both natural (recent and fossil) and synthetic. For comparative reasons and a more precise interpretation, along with OTA infrared spectroscopy was used as a method commonly applied for the investigation of fossil resins. The results obtained prove that the OTA method may be very useful for diversification of different kinds of resins. The parameter most valuable for the preliminary characteristics of resins and the evaluation of their transformation was found to be the mass loss recorded on TG curves in three definite temperature ranges. [ABSTRACT FROM AUTHOR]

Corporeality permeates the concept of something as seemingly disembodied as minerals or the earth, as we naturally perceive our surroundings through the prism of our own bodily experience. Using the examples of two objects from late antique and early Islamic Egypt, traditionally categorized as "magical" objects, it is illustrated here how corporeality permeates the perception of earth and stones in a particular historical context. The first object examined is a black hematite stone, which most likely served to protect against or stop excessive (typically gynecological) bleeding. The second is a papyrus with a so-called judicial curse, according to which those who transgressed against the inflictor of this curse were to be swallowed by the throat of the earth. [ABSTRACT FROM AUTHOR]

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Among those who posit properties, liberals (mostly nominalists) admit abundant, ontologically free properties, which particulars possess whenever they satisfy the same predicate and belong to the same class, however artificial. I call them "L-properties" (for "Liberal"). Some liberals also admit that some few L-properties are natural, while most of them are artificial (the same applies to the corresponding classes). Others (mostly but not only realists) commit to a more discriminating use of the category: properties are sparse, they make for the objective similarities among particulars, and more importantly, they allow to analyze "objective similarity" and "class naturalness" in terms of property-possessing and sharing. They give particulars their "true nature", and I call them "A-properties" (for "Analytical"). This article provides a defense of this second type of properties, in the particular case of sortals. To that end, a new fact is put forward: that sorts are classes which are natural not as a primitive feature, but in virtue of what the particulars which belong to them are, and which makes them naturally belong to them. I then argue that this fact entails the existence of the desired type of properties, "sortal A-properties", although leaving open the question of how they should be construed. [ABSTRACT FROM AUTHOR]

The Jizerka Quaternary alluvial placer in the Czech Republic has been a well-known source of gemstones since the 16th century, and the only one in Europe that has yielded a significant amount of jewel-quality sapphire. Besides Mg-rich ilmenite ("iserine"), which is the most common heavy mineral at the locality, some other minerals have been mined for jewellery purposes. These are corundum (sapphire and ruby varieties), zircon ("hyacinth" gemstone variety) and spinel. Here, we present a detailed petrological and geochronological investigation of the enigmatic relationship between the sapphires and their supposed host rocks, supporting their xenogenetic link. Our hypothesis is based on thermal resetting of the U–Pb isotopic age of the zircon inclusion found inside Jizerka blue sapphire to the estimated time of the anticipated host alkaline basalt intrusion. The host rocks of the gemstones (sapphire and zircon) and Mg-rich ilmenite are not yet known, but could be related to the Cenozoic volcanism located near the Jizerka gem placer (Bukovec diatreme volcano, Pytlácká jáma Pit diatreme and Hruškovy skály basalt pipe). The transport of sapphire, zircon and Mg-rich ilmenite to the surface was connected with serial volcanic events, likely the fast ascent of alkali basalts and formation of multi-explosive diatreme maar structures with later deposition of volcanoclastic material in eluvial and alluvial sediments in nearby areas. All mineral xenocrysts usually show traces of magmatic corrosion textures, indicating disequilibrium with the transporting alkali basalt magma. In order to constrain the provenance and age of the Jizerka placer heavy mineral assemblage, zircon inclusion and associated phases (niobian rutile, baddeleyite and silicate melts) in the blue sapphire have been studied using LA–ICP–MS (laser ablation–inductively coupled plasma–mass spectrometry) geochemistry and U–Pb in situ dating. Modification of the zircon inclusion into baddeleyite by exposure to temperature above 1400 °C in a basaltic melt is accompanied by zircon U–Pb age resetting. A zircon inclusion in a Jizerka sapphire was dated at 31.2 ± 0.4 Ma, and its baddeleyite rim at 31 ± 16 Ma. The composition of the melt inclusions in sapphire and incorporated niobian rutile suggests that the parental rock of the sapphire was alkali syenite. The Eocene to late Miocene (Messinian) ages of Jizerka zircon are new findings within the Eger Graben structure, as well as among the other sapphire–zircon occurrences within the European Variscides. Jizerka blue sapphire mineral inclusions indicate a provenience of this gemstone mineral assemblage from different parental rocks of unknown age and unknown levels of the upper crust or lithospheric mantle. [ABSTRACT FROM AUTHOR]

Mineral identification is the first step in gemstone characterization, which is the foundation for maintaining transparency in gemstone trading. Current techniques have complex protocols and require expensive instrumentation, severely restricting their use to trained experts or large gemological laboratories and limiting the processing speed. A simple and inexpensive automatic identification instrument can fulfill the needs of the Gemology Society. Hence, we propose a portable setup for the automatic mineral identification of gemstones based on a custom‐built 405 nm Raman spectroscopy probe system. This device enables the noninvasive mineral identification of commonly encountered loose or mounted gemstone materials in the market and generates the results in seconds. It is mechanically designed to allow safe operation under normal office conditions, and the pre‐aligned sample stage significantly simplifies the sample alignment process. Fifty‐seven types of gemstone materials in the trading market were tested with the device to prove the usability of the system. The primary purpose of this device is to automatically identify the types of minerals in the gemstones. It can also be extended to identify lab‐grown gemstones in the selected mineral species. [ABSTRACT FROM AUTHOR]

The Mamfe Basin has been the subject of many studies, but some debates persist, especially concerning the stratigraphic nomenclature, corundum origin, and marine transgression. The aims of this work are (1) to propose a new lithostratigraphic nomenclature of the Mamfe Basin formation based on new field observations, (2) to determine the source rock distribution and the origin of gem deposits and (3) to correlate the Cameroon section of the Mamfe Basin with the Nigerian deposits. The main results show that the name Manyu River Group is more appropriate as the Manyu River crosses all the facies in the Mamfe sedimentary Basin belonging to the Manyu Division. According to the facies analysis, the age of deposition, the mineralogic and geochemical data such as the V vs. Al2O3 and ∑REE vs. Al2O3, TiO2 MgO, Na2O, P2O5, and CaO diagrams, this Group is composed of at least five Formations, including four Cretaceous Formations, from bottom to top: the Etoko Formation (alluvial and fluvial channel to fluvio-lacustrine deposits), the Nfaitok Formation (lagoonal deposits), the Bachuo Ntai Formation (fluvial braided channels or fluvio-deltaic environment) and the Eyumojock/Nsanaragati Formation (fluvio-lacustrine deposits) and the new Cenozoic Formation named Bakebe Formation (fluvio-lacustrine deposits). The gem minerals such as corundum, rutile, or tourmaline in the Cretaceous deposits of the Mamfe Basin are mainly detrital as indicated by the presence of worn shapes and fragments of these minerals. The presence of sapphire in the Albo-Cenomanian deposits indicates a Precambrian age of the felsic source rock, likely the plutonic rocks such as granite or pegmatite as indicated by the abundance of tourmaline and high LREE/HREE ratios (14.81–34.29) and slightly negative and positive Eu anomalies (0.85–1.15). This marine incursion in the Mamfe Basin was probably from West Nigeria, according to the geographic location of the Mamfe Basin and the general palaeogeographic evolution of the Benue Trough. [ABSTRACT FROM AUTHOR]

Green diopside is currently popular in the jewelry market due to its attractive color and excellent transparency. Gem-quality diopsides are mainly sourced from Pakistan, Italy, Russia, and other places. The color, geographic origin, and formation mechanism are the main factors affecting the value of gemstones, which can be determined by examining their gemology and composition characteristics. This study systematically characterizes the standard gemology of green diopsides from Pakistan and Russia and compares them with the blue diopsides produced within the skarn process and the diopsides from the nearby region in Russia from previous studies by gemological microscopy, spectral testing (infrared, Raman and ultraviolet-visible spectroscopy), and chemical analyses (electron probe and laser ablation inductively coupled plasma mass spectrometry). The results show that the spectral characteristics and phase composition of the green diopside samples from Pakistan and Russia have excellent uniformity and similarity. The high Cr, Fe, V, and Ni contents are the reasons why they appear as green. Meanwhile, the elemental characteristics of the diopside are effective tools for distinguishing different origins of different diopsides. The Russian green diopsides have higher contents of Sr, Sc, Zr, and rare earth elements (REE), indicating that they are related to alkaline ultrabasic rocks, and the source of the diopside sample from Pakistan is metamorphic rock. [ABSTRACT FROM AUTHOR]

Absorption spectroscopy has been widely used in gemstone societies as it enables the identification of the origin and post-treatment of gemstones in a non-destructive way. The infrared (IR) range is critical for studies of gemstones such as corundum, emerald, and diamond. Regarding the corundum sample, absorption peaks related to the -OH bond could be used as an index for heat-treatment detection, and different types of inclusions could be identified by analyzing the IR absorption spectrum. The most widely used method for measuring IR absorptions is Fourier-transform infrared spectroscopy (FTIR), which was designed based on the working of the Michelson interferometer. However, FTIR has a few limitations, such as a long measurement time and difficulty in sample placement, which limits its full automation capability. In this study, a mid-infrared (MIR) spectrometer relying on the upconversion phenomenon of non-linear crystals was used to measure the absorption spectra. Corundum with heat treatment features and/or with different common types of inclusions were measured by both transmission and reflection modes. After comparison with the FTIR spectra captured on the same sample set, the same target peaks could be captured with a shorter measurement time and easier operation. The developed MIR spectrometer could directly measure the absorption spectrum in the 2–4.5 µm (2200–5000 cm−1) range within a few seconds. Meanwhile, as both transmission and reflection modes were available, both loose and mounted gemstones could be measured, supporting the widespread use of this device in large-scale production and its ability to achieve full automation. [ABSTRACT FROM AUTHOR]

Abstract. Jewellery is both economically and affectively a highly invested category of artefact. Diamonds -- which became the favoured gem-stones in European societies from the late seventeenth century -- offer a historical index of value in relation to the consumption of luxuries. At the same time, they are embedded in myth in ways that lend the circulation, exchange and wearing of diamonds very particular resonances. As minerals, once cut and polished, diamonds attract the eye and thus serve as a metaphor for the gaze in Lacanian psychoanalysis. This paper brings together questions concerning visuality as a historically specific experience in the early modern period and issues of what is meant by consumption as a process that is not only economic and social but also psychic. [ABSTRACT FROM AUTHOR]

Yogo Gulch in central Montana is one of the most important gem deposits in the United States. Although very little material has been recovered there in recent years, it has produced several million carats of rough sapphire over the course of its history (Voynick, 2001). These stones, known for their vibrant untreated blue color and high clarity, have always commanded a price premium, especially in sizes larger than 0.75 ct. This paper offers a thorough gemological characterization of Yogo sapphire, which may be unfamiliar to many gemologists. Fortunately, Yogo sapphires are unique and experienced gemologists can easily separate them from gem corundum of different geographic origins throughout the world, making it possible to determine the provenance of important stones from this deposit. [ABSTRACT FROM AUTHOR]

In this paper, Nanoparticle-Enhanced Laser Induced Breakdown Spectroscopy is applied to transparent samples and gemstones with the aim to overcome the laser induced damage on the sample. We propose to deposit a layer of AuNPs on the sample surface by drying a colloidal solution before ablating the sample with a 532 nm pulsed laser beam. This procedure ensures that the most significant fraction of the beam, being in resonance with the AuNP surface plasmon, is mainly absorbed by the NP layer, which in turn results the breakdown to be induced on NPs rather than on the sample itself. The fast explosion of the NPs and the plasma induction allow the ablation and the transfer in the plasma phase of the portion of sample surface where the NPs were placed. The employed AuNPs are prepared in milliQ water without the use of any chemical stabilizers by Pulsed Laser Ablation in Liquids (PLAL), in order to obtain a strict control of composition and impurities, and to limit possible spectral interferences (except from Au emission lines). Therefore with this technique it is possible to obtain, together with the emission signal of Au (coming from atomized NPs), the emission spectrum of the sample, by limiting or avoiding the direct interaction of the laser pulse with the sample itself. This approach is extremely useful for the elemental analysis by laser ablation of high refractive index samples, where the laser pulse on an untreated surface can otherwise penetrate inside the sample, generate breakdown events below the superficial layer, and consequently cause cracks and other damage. The results obtained with NELIBS on high refractive index samples like glasses, tourmaline, aquamarine and ruby are very promising, and demonstrate the potentiality of this approach for precious gemstones analysis. [ABSTRACT FROM AUTHOR]

This article presents a detailed history and exegesis of the 1798 paper of Charles Greville and Jacques-Louis Count de Bournon, “On the Corundum Stone from Asia.” This was the first published argument to establish that the mineral corundum was related to, or identical with, the ruby and the sapphire. It was also the first time that the science of crystallography, recently developed in France, was publically introduced to a British scientific audience. René Just Haüy’s theory of the three-dimensional structure of minerals proposed a new kind of extension of chemistry into the solid state. The story of corundum illustrates the new and sophisticated mineralogy that had emerged in the late eighteenth century and how an increasingly global natural history relied upon extended networks of trade and empire. It shows also how mineralogical debates had begun to move beyond the private and restricted milieux of mining schools and wealthy collectors and into more public scientific fora. [ABSTRACT FROM AUTHOR]

This paper presents detrital zircon ages obtained in rocks of the Embu Complex, southeastern São Paulo State, Brazil. The Embu Complex encompasses a Paleoproterozoic basement represented by migmatitic hornblende and biotite orthogneisses covered by (kyanite)-(sillimanite)-(garnet) bearing biotite-muscovite schists and paragneisses with decametric intercalations of quartzites and calcsilicate rocks. In the studied area this metasedimentary sequence is intruded by the porphyritic Serra do Quebra Cangalhagranite. Through field and microstructural studies, four ductile deformational phases wereidentified. Metamorphic events related to the Brasiliano Orogeny that affected the studied rocks were dominantly under medium temperature and pressure conditions, from greenschist to middle amphibolite facies. Detrital zircon crystals from a ∼10 m thick quartzite layer were analyzed by LA-ICP-MS resulting in a wide range of ages between 2100 and 600 Ma that fall mainly in four groups: the first group between 2.1 and 1.6 Ga, with apex at 1.7 Ga; two less expressive Mesoproterozoic groups with values between 1.6 and 1.2 Ga; and a fourth group with values between 1.2 and 0.6 Ga. Considering the geochronological data, the sedimentation of the basin began after 852 ± 40 Ma (the youngest igneous grain) and finished before ∼786 Ma (metamorphic rim). The age of the intrusive Serra do Quebra Cangalha granite (∼680 Ma) is consistent with this minimum age. The opening of the basin could be related to the break-up of Rodinia, which resulted in several small continents, among them the Paranapanema and São Francisco paleocontinents. Comparing these data with similar provenance data from the Apiaí terrane, itseems probable that the Embu Complex was physically connected with it during most of their evolution. [ABSTRACT FROM AUTHOR]

• Migrations in the LC 2–3 created a novel cultural entity in the Southern Caucases. • Arrival of Mesopotamian populations led to mixing and genesis of cultural practices. • Material culture shows "Middle Ground" arenas where habitus was negotiated. • "Middle Ground" suggests cultural genesis during close and sustained interaction. The Late Chalcolithic Leilatepe "phenomenon" in the Southern Caucasus has often been regarded as the product of Mesopotamian incursions into the region for the purpose of acquiring metals and semi-precious stones for trade. The material evidence has shown clearly that these migrations resulted in the development of both hybridised and altogether new ways of engaging with the world, including novel architectural, metallurgical, ceramic, lithic, and ritual technologies and practices. This paper approaches this period of intense cultural interaction from a practice theory lens, aiming to view the social dynamics and processes associated with the emergence of Leilatepe "culture". In doing so, we draw from Richard White's Middle Ground concept to illustrate how new social practices emerge when two cultural groups with distinct habitus come into close and sustained contact with each other. Our research indicates that, while trade was likely an important aspect of the Leilatepe phenomenon, a number of factors also point to a sustained migration or migrations by a broad swath of Mesopotamian society who arrived in the region due to a combination of push and pull factors, and did not just engage in extractive trade, but settled permanently, creating new social realities. [ABSTRACT FROM AUTHOR]

Financial institutions are undergoing the so-called "de-perimeterization." The security model up to today is heavily dependent on "border patrols" focusing mostly on providing a secure perimeter while the internal network is inherently trusted. In the upcoming borderless networks, the focus is shifting to protection of the data itself, considering the full lifecycle or switching toward context-aware defensive strategies also known as zero trust networks. The focus of this work is to critically discuss existing threat modeling methodologies, available and used in the financial services sector (FSS). The objective is to investigate the extent at which existing methodologies cover the different threat actors & events and if they reflect the current threat landscape in the FSS. The investigations are supported by a real-world case study to uncover if any process can reflect the current threat landscape without any customizations or special know-how, and whether the final outcome helps in reaching a secure or compliance state. Through the case study, it is evidenced that by utilizing the IRAM2 methodology resulted in a high ratio of compliance, however, considering the Crown Jewels of a Financial Institution (FI), a secure, as much as possible, state should be the desired outcome. [ABSTRACT FROM AUTHOR]

Spinel is a precious gem with a long history, but people are far less familiar with it. Previous studies on Mogok spinel from Myanmar focused on inclusion analysis, chromogenic mechanism with a single-color gemstone and heat treatment, whereas systematic studies on varicolored gem-grade spinel are lacking. In this study, the gemological and geochemical analysis of four colors of spinel samples from Mogok were carried out for basic gemology, inclusion morphology and identification, spectroscopy and geochemistry. The aim was to explore the occupation of elements of spinels in the crystal structure, as well as the chromogenic mechanism of varicolored spinels and the geological and geodynamic conditions of the formation. Mogok spinel samples are characterized by octahedral negative crystals filled with calcite and chondrodite inclusions, indicating that they are derived from a marble metamorphic-type deposit. The spinel samples of four colors are magnesia–alumina spinel (MgAl2O4). The contents of V and Cr in Mogok spinel are generally high, with a significant high content of Zn being the most characteristic, and trace elements vary greatly. The infrared spectra of spinel samples in different colors are basically similar. According to the UV–Vis spectrum, pink and red samples are mainly colored by Cr and/or V, whereas orange samples are mainly colored by V. Two wide absorption bands in the range 300~600 nm are mainly attributed to the spin-allowed transition and spin-forbidden transition of Cr3+ and/or V3+. The purple samples are mainly colored by Fe and the UV–Vis spectrum is mainly attributed to the spin-forbidden transition of TFe2+. This study is a favorable supplement to the research on Mogok spinels of various colors from multiple perspectives. [ABSTRACT FROM AUTHOR]

Iconic Specimens Doubtless, these large almandine garnets will become known as classics, similar to the almandine crystals from Russell, Massachusetts. Large, sharply formed almandine crystals from Mt. Marie were first recovered in May 2017. The pegmatite units, exposed between overburden-concealed areas, are sufficiently discontinuous to prevent determining whether the mountain crest is one pegmatite or a swarm of several pegmatites. These garnets are late crystallization products, which formed near the end stage of the primary pegmatite crystallization, as indicated by the crystals' location in contact with quartz core segments, which usually (but not always) is the last crystallized part of the pegmatite (London [13]; Roering [16]). [Extracted from the article]

Recently found historical jewellery (Czech Republic) was subjected to detailed analyses to determine the gem inlays and the gold framework in which they are embedded. Such find fits into European jewellery archaeological artefacts containing similar stones from around the fifth century CE. The gemstones were analysed with optical microscopy and Raman micro-spectroscopy to determine their mineralogical characteristics and to find out typical structural-chemical differences based on which their provenance can be found. The results of this measurement discovered two main types of minerals from the garnet group, almandine and pyrope, where pyropes have been identified as Bohemian garnets thanks to the typical photoluminescence (PL) of chromium and vanadium impurities. The craftsmanship and processing of the goldsmith work were studied using X-ray computed tomography. Such a technique is an excellent contribution for detecting and visualising the internal parts hidden behind the placement of the stones. For this reason, 3D visualisation was used to describe and better understand all preserved parts. According to this object's very high cultural and historical value, the chosen methods are suitable for non-destructive study while proving to be essential to deepen our knowledge in archaeometric investigations focused on jewellery from Late Antiquity (with possible application to the jewellery from other periods). Based on the findings presented in this study, it is one of the world's oldest documented items using Bohemian garnets in jewellery. These findings underscore the tremendous economic and political importance of Bohemian garnet mineral resources altogether, with a second completely different type of garnet believed to have originated in distant India or Sri Lanka that was used in jewellery across Europe in Late Antiquity. [ABSTRACT FROM AUTHOR]

Silver nanoparticles have been prepared from a chemical reduction approach and supported on modified TEOS (tetraethylorthosilicate) xerogels to be studied as a nanocatalyst in the conversions of benzopyranopyrimidines (with primary as well as secondary amines along with the mechanism by trapping the imine intermediate) and also in the synthesis of gem-bisamides. Different conditions for the performance of the nanocatalyst have been screened and tolerance with respect to variable functionalities has been observed, resulting in excellent yields; and confirmation of products synthesized has been done using studies like 1H NMR, 13C NMR and mass analysis. Also, SEM-EDX and TEM of the nanocatalyst have been performed to know the internal and external morphology, size and elemental composition. UV and XRD analysis to confirm the silver nanoparticles’ and xerogel's presence, TGA to study the thermal stability and FTIR to study the modification pattern of the nanocatalyst have been undertaken and presented in this work. [ABSTRACT FROM AUTHOR]

Most turquoise objects from early Neolithic sites in China are pendants made of a single material. From the later Neolithic period, however, people started to create turquoise ornaments with two or more composite materials. Ornaments were inlaid with turquoise and other materials using new techniques. In the Early Bronze Age, the turquoise production process reached its peak. At the Erlitou site, archaeologists found a large dragon-shaped turquoise mosaic, a variety of animal-shaped turquoise decorations, and turquoise workshops. The purpose of this paper is to understand the importance of turquoise products in the formation process of early state formation in China by analyzing the following topics: the technological evolution of turquoise manufacture, the combination of composite materials, the use of adhesive in turquoise inlay, and the associated production processes as they developed from the Neolithic to Early Bronze Age. [ABSTRACT FROM AUTHOR]

An intellectual journey that began with the discovery of strange attractors derived from Chua's circuit, their translation into physical shapes by means of 3D printers, and finally, to the production of jewelry is presented. After giving the mathematical characteristics of Chua's circuit, we explain the chaotic design process, used for creating jewels, providing specifications of the used methodological approach, for its reproduction. We discuss the feasibility of this approach and the transmission of scientific contents on chaos theory, usually restricted to university students, in a high school Science, Technology, Engineering, Art, and Mathematics course, for the realization of advanced educational processes, implemented both in computational and real environments. We think that the idea of transforming science into art forms can drive students in acquiring scientific knowledge and skills, allowing them to discover the inner beauty of chaos. [ABSTRACT FROM AUTHOR]

Tourmaline mining in Maine began with the first find of gem-quality tourmaline at Mt. Mica in 1820 and continues today at numerous localities. In October 1972, on the eastern slopes of Plumbago Mountain in Newry, Maine, the largest single discovery of gem-quality tourmaline in North America was unearthed - more than a ton in all. Mt. Mica, the Havey quarry, and the quarries at Mt. Marie are all notable contemporary locations for gem tourmaline in Maine. [Extracted from the article]

The jet stone was used for amulets from antiquity to modern times. Legends and beliefs concerning it flourished. It is black and, being similar to amber, could be burned to obtain a smoke used for magical and medical purposes. Some religious ceremonies used it for attracting snakes. It was often confused with other stones, such as aetites and serpentine and even with agate because it was also called antachates. [ABSTRACT FROM AUTHOR]

Roman gems have continued to be discovered in Roman Britain and published in archaeological reports and notes since the author completed his Corpus of Gems from British Sites in 1978. A new source of glyptic material can be found in the on-line publication of Portable Antiquities (Portable Antiquities Scheme) which includes intaglios, most of them found without stratigraphical context, by users of metal detectors, though many are set in rings, which provide significant aids in dating. Others were clearly re-used as they are set in seal matrices or medieval rings and were frequently freshly imported at that period from southern Europe. In the High Middle Ages, as in Roman times, intaglios reflect the interests, and patterns of thought of those who wore and valued these beautiful objects. [ABSTRACT FROM AUTHOR]

Seashells and Snails are known and used all over the world. They were used as raw materials for making ornaments and jewelry or as a source of food by eating the live animal inside. Seashells had special religious importance in many civilizations, especially the ancient Egyptian civilization, as shown through the actual use of shells as amulets or through simulations by making them of precious stones or metals like gold as amulets for protection. Shells also had funerary importance and were placed with the dead in the tombs among their offerings to benefit them in the other life. Many shells were found in several tombs in Egypt during the Neolithic period. Shells were a symbol of protection from the bad eye because of their similarity with the shape of the eye, so the early man thought that the shell prevented the "evil eye", where it was used as protection against evil, especially for women during pregnancy and childbirth. There were many other uses for shells, some seashells were used as containers for cosmetics or preserving colors, and some kinds of snails were used to extract dyes. Shells were also used as a means of social exchange or swap, commonly used as a means of commercial exchange. Shells still have ideological significance in many primitive tribes. [ABSTRACT FROM AUTHOR]