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Minerals and metals are crucial raw materials for industries and a major source of development for the country. In India there has been a pronounced growth in the exploration for minerals both in terms of quantity and value. To further enhance the growth rate and remove any bottleneck, the government has taken several legislative reforms through more transparency and non-discretion by way of first-come, first-served basis in the allocation of mineral concessions, through Mines and Minerals (Development and Regulation) (MMDR) Amendment Act, 2015. Recently, MMDR Act, 1957 has been amended through the Mines and Minerals (Development and Regulation) Amendment Act, 2021 vide notification dated 28.03.2021 for improving ease of doing mineral production and business in the country and help increase Gross Domestic Product (GDP). Exploration of energy-critical minerals, fertilizer minerals, precious metals and stones, strategic minerals and deep-seated minerals which are otherwise difficult to access and for which the country is mainly dependent on imports, needs to be prioritized. Enhanced exploration and mining can significantly reduce India's import dependence on mineral and metals and help economic growth. For comparison, only 10% of obvious geological potential (OGP) area of India has been explored while Australia has explored more than 90% of its area. In this paper, some of these legislative reforms and challenges to provide an impetus to mineral exploration are discussed. [ABSTRACT FROM AUTHOR]

The material characterization of nineteenth-century artifacts is of great interest, due both to the breakthrough technological advances and to the unprecedented spread of forgeries of antiquities which took place in that period. However, this type of artifacts has been largely overlooked in the past. In this paper we present the compositional analysis of gold jewels by the Castellani, one of the most important families of goldsmiths in nineteenth-century Europe. The use of a portable micro-XRF spectrometer, specifically developed for jewellery analysis at the Centro Nacional de Aceleradores (Seville), allowed us to analyse, in a completely non-invasive way, the alloys, joining techniques and surface treatments of the jewels of the Castellani collection at the National Etruscan Museum of Villa Giulia in Rome. The addition to the spectrometer of a second X-rays detector with a zinc filter allowed us to check the possible presence of low amounts of cadmium, a metal added to gold soldering only from the nineteenth century and often used in authenticity studies. Moreover, the relative intensities of the Au X-ray lines were studied in order to check non-invasively the presence of surface enrichments in gold. [ABSTRACT FROM AUTHOR]

India has its unique and rich cultural heritage. One such uniqueness in India is ancient paintings. Especially in South India, Tanjore paintings are very popular. These paintings are made during 1010 AD with vibrant colours, gold, silver and precious stones. These paintings are the memorabilia of the great Chola kingdom. These paintings can be seen in great Brahadeeshwara Temple walls till now. Damages to these paintings happen due to varying environmental conditions and rituals followed throughout the year. Hence, preserving these heritages could be an additional source in National Cultural Museum and cultural libraries. This paper focuses towards the restoration of such ancient painting images that can be digitized and archived for the future use of aesthete. The painting images are preprocessed using Weiner filter for removing the background noises since its PSNR value is higher than Gaussian and Median filters. The preprocessed image is then applied to restoration algorithm. Two types of restoration algorithm is attempted, image segmentation and in-painting algorithm. The degraded image was restored efficiently with in-painting algorithm than segmentation algorithm. Further research can be focused towards automatic adaptive selection of patch based on the nature of images. From the results it is observed that with in-painting algorithm the image restoration is better than the segmentation algorithm for degraded painting images. [ABSTRACT FROM AUTHOR]

The Peleș National Museum in Sinaia, Romania, includes within its collection of musical instruments a unique harpsichord of the Taskin workshop. The instrument is representative of the eighteenth century French harpsichords, finished in 1772 by Taskin Pascal, a master instrument-maker of his time. This paper presents the results of a comprehensive diagnostic investigation carried out on the exterior decoration of the harpsichord, by means of multiple non-invasive and micro-invasive analytical techniques: multispectral imaging, X-ray fluorescence (XRF) spectroscopy, laser-induced breakdown spectroscopy (LIBS), Fourier transform infrared spectroscopy (FTIR), and optical microscopy (OM). Imaging investigation highlighted various past interventions and restorations—fillings, consolidation and chromatic reintegration of the paint layer, as well as some interesting details related to the preparatory layer and on the painting technique. Results of the elemental analysis indicated that a rich color palette was used for the luxurious decorations: vermilion for most of the red areas, lead white, a copper-based pigment for the blue and violet hues, along with Prussian blue, chromium oxides for the green tones and possibly emerald green, and iron oxides for the red, yellow and ochre tones. FTIR analysis highlighted the existence of two-layers ground based on the first layer of chalk and animal glue, covered by a second oil-bound layer of lead white. Metal soaps, gypsum, barium sulfate as well as an intermediate sizing layer based on shellac were also identified. Examination of samples' cross-sections revealed a rich stratigraphy, up to ten layers being highlighted for samples taken from the case sides' painting. The presence of two gold foils on the gilded areas, one at the top and the other within the intermediate layers, provides clear evidence of later interventions. The corroborated results offer valuable physico-chemical insights on the complex history of this prestigious harpsichord with remarkable aesthetic and historical value, as well as key information for its most suitable restoration approach. [ABSTRACT FROM AUTHOR]

Alexandrites are remarkable and rare gemstones. They display an extraordinary colour change according to the ambient lighting, from emerald green in daylight to ruby red in incandescent light from tungsten lamps or candles. While this colour change has been correctly attributed to chromium impurities and their absorption band in the yellow region of the visible light spectrum, no adequate explanation of the mechanism has been given. Here, the alexandrite effect is fully explained by considering the von Kries model of the human colour constancy mechanism. This implies that our colour constancy mechanism is real (objective) and primarily attuned to correct for the colour temperature of black-body illuminants. [ABSTRACT FROM AUTHOR]

Since the inception of the World Trade Organisation (WTO) in 1995, member countries have been heavily relying on the organisation's Dispute Settlement System (DSS). Exploiting a new database on WTO litigations between 1995 and 2014, this paper describes disputes initiated over this period and identifies potential sources of bias concerning the participation of developing countries. The analysis builds on three different models to determine country i's probability of initiating a dispute against country j. Either it depends on the two countries' structure of trade (the rules-based model), or it is also affected by country i's or country j's specific characteristics (the unilateral power-based model), or it is also affected by bilateral economic and trade relations between countries i and j (the bilateral power-based model). We find that country i's structure of trade with j plays an important role in explaining the probability that i initiates a dispute against j under the DSS. We also find clear evidence with regard to the importance of two independent variables: first the legal capacity of i (a variable related to the unilateral power-based model) and second the trade retaliatory capacity of i against j (a variable related to the bilateral power-based). Almost all these results hold when testing for both the likelihood of initiating a dispute and for the number of disputes initiated before the WTO. [ABSTRACT FROM AUTHOR]

Corundum crystals of semi-gem quality (sapphire) formed in a syenitic dyke around the plutonic rocks in the Alvand igneous-metamorphic complex were studied by Sheikhi Gheshlaghi et al. (2020). These authors studied field relations and petrography of a corundum-bearing pegmatite, and proposed a genetic model for corundum formation. Although studies on whole rock chemistry of corundum-bearing pegmatites and oxygen isotope data for corundum by these authors are valuable, some of their reports and findings – such as the sharp contact between corundum-bearing pegmatite and Alvand syenite, the lack of tourmaline group minerals in corundum-bearing pegmatite, the presence of syngeneic quartz inclusion in corundum and the genesis of corundum as a result of kyanite break down – are in contrast with our own observations and findings. Neither the P-T conditions, nor the volatile-bearing minerals present, are in favour of formation of corundum from kyanite breakdown. Based on present authors' studies, mineral chemistry of corundum in the Alvand area clearly indicates magmatic origin. [ABSTRACT FROM AUTHOR]

The global demand for jewellery and precious stones has contributed to the recent growth in gemstone mining and its industry. While this trend is expected to soar in the coming years, a proper assessment of the environmental effects of gemstone mining is required to prevent further ecosystem degradation. This study assessed the impact of mining on the soil and water at the Ofiki gemstone mining site in southwestern Nigeria. Soil and water samples were collected from the mining site and the adjoining undisturbed areas. The physicochemical properties of the samples were analysed using standard procedures, and the results were compared with the World Health Organization (WHO) and other standard threshold limits. The results indicated that mining at the site caused a substantial loss of soil organic matter, nitrogen and potassium necessary for plant growth. Furthermore, the soil around the mining site was highly acidic, with low macronutrient concentrations in and around the site. Additionally, surface water at the mining site was highly acidic, with phosphate and iron concentrations exceeding WHO permissible limits. However, other physicochemical properties of the water samples in and around the mining site were within WHO permissible limits. [ABSTRACT FROM AUTHOR]

This paper is concerned with the $(p,q)$-analog of Bernstein operators. It is proved that, when the function is convex, the $(p,q)$-Bernstein operators are monotonic decreasing, as in the classical case. Also, some numerical examples based on Maple algorithms that verify these properties are considered. A global approximation theorem by means of the Ditzian-Totik modulus of smoothness and a Voronovskaja type theorem are proved. [ABSTRACT FROM AUTHOR]

Abrasive water jet (AWJ) machining is characterized by its versatility, i.e., it can be applied to a wide variety of materials. Currently, one important application is for manufacturing gem artifacts, especially agate, which is the largest gemological material produced in the state of Rio Grande do Sul. However, one of the main obstacles to its popularization is the cost associated with the process, due to the high abrasive consumption required for a good quality surface finish. In this sense, this research paper presents a study of the influence of the main process parameters (traverse speed and abrasive mass flow rate) on the surface finish of agates machined by AWJ. The experimental procedure used three different traverse speeds, four abrasive mass flow rate in two different thicknesses of agate's plates. Surface roughness and angle of striation marks were observed for different depths from the jet entrance surface. Results were analyzed using analysis of variance (ANOVA). Through the study, it was found that the machined surface finish varies according to the depth from the entrance surface of the abrasive jet. Also, it was concluded that the surface finish of the machined surface by AWJ (surface roughness and striation marks) of the agate's plates machined by AWJ exhibits similar results for both thicknesses tested. ANOVA showed that the traverse speed is more significant than abrasive mass flow rate for the material studied with respect to the surface finish. Thus, for a small material thickness, it is possible to use high traverse speed and low abrasive mass flow rate which makes the process more economical. [ABSTRACT FROM AUTHOR]

Spectroscopic and microstructural studies of ruby variety corundum samples of Sinapalli, Odisha have been carried out using various physical techniques. FTIR, Micro Raman, photoluminescence along with microstructural and energy dispersive x-ray spectroscopy (EDAX) data reveal presence of hydroxylated form of alumina on the surface with presence of Cr chromophores. These gemstones contain zircon and rutile inclusions. Upon heat treatment, the colour of the ruby variety of gemstones improved by dissolving rutile inclusion inside the corundum lattice. Detailed data of the both untreated and heat treated samples are discussed in this paper. [ABSTRACT FROM AUTHOR]

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 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]

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]

This article analyses the exploitation of luxury products such as pearls and mother of pearl, a seldom-examined facet of maritime archaeology. This issue will be approached from an archaeology of production perspective, taking into account the whole chaîne opératoire, including harvesting the resource, marketing it, and mounting it in different supports. We shall also examine the meaning of these resources and some extravagant practices for which they were used during antiquity. We shall pay special attention to the artisans, as well as the production methods used to process these resources and assemble them. The study will focus on the Roman period, and Hispania will be used as case study. The Iberian Peninsula is surrounded by plentiful seas, but this specific issue had been paid no specific attention to date. An unpublished catalogue of jewels decorated with pearls and other ornaments is presented, which confirms the importance of these resources in ancient Roman markets. [ABSTRACT FROM AUTHOR]

In the Hamadan region, Sanandaj-Sirjan Zone (SaSiZ), W Iran, a pegmatite-aplite vein occurs that contains up to 15 vol% sapphire. The Hamadan sapphire is black to blue, and translucent to opaque, which reveals its semi-gem and gem quality. On the basis of petrographic studies, the Hamadan sapphire-bearing pegmatite-aplite vein represents alkali syenitic to syenitic composition and its adjacent granitoids have a range of composition from syenitic to quartz monzonite and granodiorite. New petrographic, whole-rock geochemical data and δ18O values [9.30–12.45‰VSMOW (Vienna Standard Mean Ocean Water)] suggest crustal origin for the peraluminous, S-type and alkaline sapphire-bearing pegmatite-aplite vein. The presence of syngenetic quartz inclusions in the sapphire, and some similar physical-gemological signatures (e.g., parting patterns and angles) of the Hamadan sapphire and kyanite support the generation of the sapphire at the expense of kyanite. In addition, a secondary metasomatic stage may have played a minor role in formation of the sapphire grains. The results indicate an important role for the mafic magmas in triggering crustal anatexis and gem crystallization in continental subduction zone settings. [ABSTRACT FROM AUTHOR]

We study the breaking of Casimir scaling, C F / C A , due to the evolution of jets in a hot and extended medium. By using JEWEL, a medium modified Monte Carlo event generator validated for a wide set of observables, we are able to study separately the development of quark and gluon-initiated jets produced back-to-back with a Z - boson. Focusing on the p T distribution, we conclude first that the colour charge ratio is constant but larger than Casimir scaling for high p T jets. In addition, our results seem to indicate that the medium induced cascade is more similar between quarks and gluons, thus driving the overall medium shower scaling away from the vacuum expectation. Finally, we compare our results to another Monte Carlo generator and observe the same scaling violation. [ABSTRACT FROM AUTHOR]

SE Kenya is the world’s largest producer of green vanadium grossular gemstones (tsavorite). Samples from one of the mines near Mwatate, and of occurrences in Tanzania yielded remarkable new insights into the genesis of tsavorite. Graphite is intimately associated with V-grossular and is one of the keys to understanding its origin. In the course of this study we found five different types of graphite. Surprisingly, in one graphite type the “Raman-forbidden” and IR-active 867 cm− 1 band was observed. In this communication, we attempt to find an explanation for this unusual phenomenon. Additionally, our observations also address some of the issues pertaining to the origin of the green grossular-dominated rocks (grossularites), as well as the gem quality tsavorite crystals, since we propose that the anomalous spectroscopic behavior of the graphite is related to the unusual conditions during crystallization of both the grossular and graphite from a near-supercritical volatile- and sulfur-rich silicate melt. The massive green vanadium grossular contains abundant unequivocal crystallized melt inclusions, while the transparent gem quality grossular (tsavorite) displays only fluid inclusions. On the basis of inclusion studies we suggest that anatectic melts originated in the peculiar evaporitic host lithology of the tsavorite deposits. Near peak metamorphic temperatures (~ 700 °C) these liquids occurred as a supercritical volatile-rich “fluid/melt phase” characterized by complete miscibility between H2O and silicate liquid. Relatively dry liquid batches precipitated non-transparent green grossular, whereas wet batches segregated fluids that formed transparent tsavorite. [ABSTRACT FROM AUTHOR]

Emerald, the green gem variety of beryl (Be3Al2Si6O18), is the third most valuable gemstone after diamond and ruby. The green colour appearance of the crystal is due to trace of Cr3+ and V3+, which replaces Al3+ ions in the crystal lattice of beryl. The hue of green colour of emerald depends on the quantity of Cr3+ and V3+ present in the crystal. Be is incorporated along with Cr and/or V during the process of crystallization. Since Be is relatively rare in the upper continental crust, therefore specific geological and geochemical parameters are required for Be to be incorporated in the crystal lattice of emerald.The present work was carried out to understand the lithological and structural control of emerald occurrences in and around Gurabanda area within the Singhbhum shear zone (SSZ) of Singhbhum crustal province, eastern India. The biotite and serpentine schist belong to the Paleoproterozoic Dhanjori Group and constitute the major lithology of the area. Pegmatite and biotite schist contains a variety of gem minerals in abundance in the area and the gem quality emerald occur at the contact zone of quartz vein and mica-schist. Lithology and structure are the main controlling factors of gem-mineralization in the study area. The study indicates that regional metamorphism and deformation processes along the shear zone played a significant role in the formation of emerald deposits. It is inferred that Singhbhum shear zone facilitated a favourable condition, where the Be bearing pegmatites interacted with Cr bearing mica schist or ultramafic rocks to produce emerald crystal. [ABSTRACT FROM AUTHOR]

The mineral and fluid inclusions trapped by gemstones during the metamorphism of carbonate platform successions are precious markers for the understanding of gem genesis. The nature and chemical composition of inclusions highlight the major contribution of evaporites through dissolution or fusion, depending on the temperature of formation from greenschist to granulite facies. The fluids are highly saline NaCl-brines circulating either in an open system in the greenschist facies (Colombian and Afghan emeralds) and with huge fluid-rock metasomatic interactions, or sulphurous fluids (ruby, garnet tsavorite, zoisite tanzanite and lapis-lazuli) or molten salts formed in a closed system with a low fluid mobility (ruby in marble) in the conditions of the amphibolite to granulite facies. These chloride-fluoride-sulphate ± carbonate-rich fluids scavenged the metals essential for gem formation. At high temperature, the anions SO , NO , BO and F are powerful fluxes which lower the temperature of chloride- and fluoride-rich ionic liquids. They provided transport over a very short distance of aluminium and/or silica and transition metals which are necessary for gem growth. In summary, the genetic models proposed for these high-value and ornamental gems underline the importance of the metamorphism of evaporites formed on continental carbonate shelves and emphasise the chemical power accompanying metamorphism at moderate to high temperatures of evaporite-rich and organic matter-rich protoliths to form gem minerals. [ABSTRACT FROM AUTHOR]

Luxury goods such as gemstones constitute a challenge for moving towards a sustainable society. From a purely bio-economic perspective, such goods consume planetary resources to provide a human 'want' rather than a 'need'. However, their extraction or manufacturing also provides important livelihoods for communities along the supply chain and hence contribute towards development outcomes. Comparing mined versus synthetic gems can provide consumers with important benchmarks on choice. The energy usage and emissions in mined versus lab-created diamonds was evaluated, based on industrial data, since these two factors are often a general indicator of environmental impact that can be useful in product comparisons. Depending on the process and the location of the mine, the data can be highly divergent and cannot be used as a singular measure of environmental impact. There is a need to develop life cycle analysis techniques from industrial ecology to conduct a detailed comparison of synthetic versus mined stones. Informed consumers could help to transition this luxury good towards a mix of mined and synthetic gems that best meet ecological and social metrics of sustainability. [ABSTRACT FROM AUTHOR]

Several mainly silicate minerals in their gemstone varieties have been analysed by the Gem Raman portable system by Gemlab R&T, Vancouver, Canada, in order to ascertain the general performance of this relatively non-expensive tool developed exactly for the purpose of gemstone identification. The Raman spectra of gemstones acquired by this system have been subsequently critically compared with the data obtained by several other portable or handheld Raman instruments. The Raman spectra acquired with the Gem Raman instrument were typically of lesser quality when compared with the spectra taken by other instruments. Characteristic features such as steep baseline probably due to the fluorescence of the minerals, Raman bands much broader and therefore less resolved closely located Raman bands, and generally greater shifts of the band positions from the reference values were encountered. Some gemstone groups such as rubies did not provide useful Raman spectra at all. Nevertheless, general identification of gemstones was possible for a selection of gemstones. [ABSTRACT FROM AUTHOR]

Temperature-induced sign reversal of magnetization in the vicinity of room temperature is reported in a single-phase spinel compound of Ni(CrFe)O. The magnetic compensation temperature is 358 K. The mechanism of magnetization reversal is explained by considering the different temperature dependences of sublattice magnetization. Bipolar switching of magnetization at room temperature is demonstrated by just varying the magnetic field from + 200 to + 2050 Oe, i.e., without changing the direction of the magnetic field. Tunable positive and negative exchange bias fields are observed in the vicinity of room temperature with a maximum value of 1 kOe. [ABSTRACT FROM AUTHOR]

The results of study of crichtonite group minerals in pyropes from the Internatsionalnaya kimberlite pipe are reported. Most of the studied samples are characterized by high concentrations of Sr, Ca, Na, and LREEs in comparison with minerals of the LIMA series from kimberlites of South Africa, whereas the average concentrations of Ba and K are significantly lower. Crichtonite group minerals in pyropes are characterized by predomination of Na over K in most samples and by a high concentration of AlO (up to 4.5 wt %). Findings of inclusions of crichtonite group minerals with high concentrations of incompatible elements provide evidence for the metasomatic origin of host chromium-rich pyropes. [ABSTRACT FROM AUTHOR]

We report newly obtained U-Pb SHRIMP ages of detrital zircons from metagreywackes in the Hiriyur Formation (Chitradurga Group, Dharwar Supergroup) from the central eastern part of the Chitradurga greenstone belt. U-Pb analyses yield three major Neoarchean age populations ranging from 2.70-2.54 Ga with some minor age population of Mesoarchean. The maximum age of deposition is constrained by the youngest detrital zircon population at 2546 Ma. This is the first report of the occurrence of supracrustal rocks less than 2.58 Ga in the central part of Chitradurga greenstone belt. Close evaluation of detrital ages with the published ages of surrounding igneous rocks suggest that the youngest detrital zircons might be derived from rocks of the Eastern Dharwar craton and the inferred docking of the western and eastern Dharwar cratons happened prior to the deposition of the Hiriyur Formation. The Chitradurga shear zone, dividing the Dharwar craton into western and eastern blocks, probably developed after the deposition. Furthermore, the lower intercept is interpreted as evidence for the Pan-African overprints in the study area. [ABSTRACT FROM AUTHOR]

The evolution of the structural environment of $$\hbox {Cr}{^{3+}}$$ along the solid solution $$\hbox {ZnAl}_{2-x}\hbox {Cr}_{x}\hbox {O}_4$$ has been investigated using a multi-analytical approach. X-ray diffraction confirms that the system follows Vegard's law. Diffuse reflectance spectra show a decrease of the crystal field parameter with the Cr content, usually related to the increase of the Cr-O bond length in a point charge model. This interpretation is discussed and compared to the data obtained by first-principle calculations based on density functional theory. X-ray absorption near edge structure spectra at the Cr K-edge show a pronounced evolution in the pre-edge with the Cr content, characterised by the appearance of a third feature. Calculations enable to assign the origin of this feature to Cr neighbours. The colour change from pink to brownish pink and eventually green along the solid solution has also been quantified by calculating the L*, a*, b* and x, y coefficients in the system defined by the International Commission on Illumination. [ABSTRACT FROM AUTHOR]

We introduce a new method for a task of maximal material utilization, which is to fit a flexible, scalable three-dimensional body into another aiming for maximal volume whereas position and shape may vary. The difficulty arises from the containment constraint which is not easy to handle numerically. We use a collision detection method to check the constraint and reformulate the problem such that the constraint is hidden within the objective function. We apply methods from parametric optimization to proof that the objective function remains at least continuous. We apply the new approach to the problem of fitting a gemstone into a roughstone. For this previous approaches based on semi-infinite optimization exist, to which we compare our algorithm. The new algorithm is more suitable for necessary global optimization techniques and numerical results show that it works reliably and in general outperforms the previous approaches in both runtime and solution quality. [ABSTRACT FROM AUTHOR]

The article discusses eco-chemistry of minerals highlighting the protoliths of garnetites that are found in the diamond containing rocks near the lake Kumdy Kol, North Kazakhstan. Topics discussed include study of garnet and apatite, Rare Earth Elements (REE) patterns and comparison between metasomatic and magmatic apatites. Characteristics of garnet bearing ultra-basic rocks are explored.

The effect of heat treatment on amethyst color was studied from a new perspective of chromaticity of gemstones and the cause of amethyst coloration was discussed based on the results of X-ray diffraction, ultraviolet–visible spectroscopy. The results show that the amethyst color has no significant relationship with cell parameters but the crystallinity index decreases as temperature rises. The absorption band at 545 nm in the UV–visible spectrum can be related to a charge-transfer transition of Fe3+ and O2−, which has a significant relationship with amethyst lightness and chroma. The color at different temperatures can be divided into three stages: The amethyst stage with temperature below 420 °C, the prasiolite stage with temperature between 420 and 440 °C where the color center is the most unstable, the citrine stage with temperature above 440 °C. The color change degree of heated amethyst is related to its initial color. When the initial color is darker, the color difference of heated amethyst is larger, and the easier it is to change the color after heat treatment. A more appropriate heating temperature to obtain citrine by heating amethyst is about 560 °C. [ABSTRACT FROM AUTHOR]

Through the calculation of gemological chromaticity, the green characters and range of chromaticity of 728 cabochon jadeite jade were determined, and then it studies and compares with GemDialogue color card images for jadeite-jade green quality evaluation. It is testified that the method is proved to be effective and the construction of emerald green quality grading system based on it is proved. First of all, with reference to China national standard GB/T 23885-2009 “Jadeite-jade Grading,” the color appearance of jadeite-jade color green was analyzed contrastively with the help of three pieces of GemDialogue color chip images G, Y2G, and B2G where CIE recommended standard light sources D65, A, and CWF, and then it is proposed that the best light source of jadeite-jade color green measuring and evaluating is standard D65 based on quantitative analysis of samples’ lightness L*, chroma C*, hue h0. Secondly, according to samples color green and five pieces of GemDialogue color chip images G2Y, Y2G, G, B2G, and G2B, jadeite-jade color was graded in seven levels from the best end “Fancy Vivid” to the last end “Very Light” with the contribution of five different overlap modes of three color masks: black/gray transparent, brown transparent, and black/white opaque. Furthermore, the high accuracy of the method is verified by clustering analysis and Fisher’s discrimination reversely. It draws conclusions that there are two evaluation methods of jadeite-jade color green; the first is the colorimetric way of GemDialogue color chip images, and the complementary is the way of Fisher functional method which sample parameters could be back substituted, and all these two methods could be extended to other green gem quality evaluation. [ABSTRACT FROM AUTHOR]