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The Sheahan Diamond Literature Reference Compilation - Scientific and Media Articles based on Major Keyword - Spectroscopy
The Sheahan Diamond Literature Reference Compilation is compiled by Patricia Sheahan who publishes on a monthly basis a list of new scientific articles related to diamonds as well as media coverage and corporate announcements called the Sheahan Diamond Literature Service that is distributed as a free pdf to a list of followers. Pat has kindly agreed to allow her work to be made available as an online digital resource at Kaiser Research Online so that a broader community interested in diamonds and related geology can benefit. The references are for personal use information purposes only; when available a link is provided to an online location where the full article can be accessed or purchased directly. Reproduction of this compilation in part or in whole without permission from the Sheahan Diamond Literature Service is strictly prohibited. Return to Diamond Keyword Index
Sheahan Diamond Literature Reference Compilation - Scientific Articles by Author for all years
Each article reference in the SDLRC is tagged with one or more key words assigned by Pat Sheahan to highlight the main topics of the article. In an effort to make it easier for users to track down articles related to a specific topic, KRO has extracted these key words and developed a list of major key words presented in this Key Word Index to which individual key words used in the article reference have been assigned. In most of the individual Key Word Reports the references are in crhonological order, though in some such as Deposits the order is first by key word and then chronological. Only articles classified as "technical" (mainly scientific journal articles) and "media" (independent media articles) are included in the Key Word Index. References that were added in the most recent monthly update are highlighted in yellow.
Spectroscopy is the study of the interaction between matter and electromagnetic radiation. Articles tagged with this key word are exclusively of a scientific nature and deal either with diamond crystals and how they reflect the visible light portion of the electromagnetic wave spectrum, or with the earth where the reflection of matter penetrating wavelengths is used to map the lithosphere and mantle. The latter is thus closely related to tomography and is only relevant to diamonds in helping identify those parts of the earth conducive to the formation of diamonds.
Routine trace -element capabilities of electron microprobe analysis in mineralogical investigations: an empirical evaluation of performance usingspectroM.
Canadian Mineralogist, Vol. 28, Pt. 1, March pp. 171-180
An analytical method for hydrogeochemical surveys: inductively coupled plasma atomic emission spectrometry after using enrichment coprecipitation with cobalt and amM.
Journal of Geochemical Exploration, Vol. 41, No. 3, November pp. 349-362
Laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS):rapid technique direct quantitative determination major, trace rareearth elements
Coupled substitution of Hydrogen and minor elements in rutile and the implications of high OH contents in niobium and chromium rich rutile from the upper mantle.
American Mineralogist, Vol. 78, No. 11, 12, November-December pp. 1181-1191.
Lang, A.R., Bulanova, G.P., Fisher, D., Fukert, S., Saruna, A.
Defects in a mixed habit Yakutian diamond: studies by optical and cathodluminescence microscopy, infrared absorption, Raman Scattering and photoluminesence spect
Journal of Crystal Growth, Vol. 309, 2, pp. 170-180.
Variable temperature 27Al and 29Si NMR studies of synthetic forsterite and Fe bearing Dora Maira pyrope garnet: temperature dependence and mechanisms of paramagnetically shifted peaks.
Russian Geology and Geophysics, Vol. 56, pp. 1154-1161.
Technology
Spectrometry
Abstract: The results of electron probe microanalysis of several rock-forming minerals by wavelength-dispersive spectrometry (WDS) and energy-dispersive spectrometry (EDS) are compared, and the metrological characteristics of both methods are studied. The measurements were made with the use of a JXA-8100 (JEOL) microanalyzer with five wavelength-dispersive spectrometers and a MIRA 3 LMU (Tescan) scanning electron microscope equipped with an INCA Energy 450 XMax 80 (Oxford Instruments) microanalysis system. Specimens with olivine, garnet, pyroxene, ilmenite, and Cr-spinel grains were analyzed.
The variation coefficients that characterize the repeatability of a single determination are found to be ~ 0.5% for WDS and ~ 0.9% for EDS in the compositional range of the main components (C > 10%). For minor components (1% < C < 10%), the variation coefficients are 1.4% and 3.0%, respectively, and for impurities (0.3% < C < 1%), 2.7% and 13%, respectively. For lower contents EDS is almost inapplicable. The ratio of the results obtained by the two methods is reproduced with high precision: For major components, the variation coefficient is 0.56%; for minor components, 1.7%; and even for impurities, it is ~ 8%. The magnitude of the bias is between 0.2 and 3.2 rel.%, which is acceptable.
The results show that the accuracies of WDS and EDS are similar for measuring major and minor components of rock-forming minerals. Energy-dispersive spectrometry is inferior to wavelength-dispersive spectrometry for impurities and is completely inapplicable for still lower contents. This method is easier to implement, and the results are available soon after switching on the instrument. Wavelength-dispersive spectrometry needs more time for preparation, but it ensures a precise high-efficiency large-scale analysis of samples of similar compositions, even when the element contents are lower than 1%.
GSA Annual Meeting, Paper 300-4, 1p. Abstract only Booth
Technology
Spectroscopy
Abstract: The ability to accurately determine the provenance of gem diamonds impacts economic, political, and national security arenas. Currently, provenance determinations rely on: 1) gemological and mineralogical features of stones, such as spectroscopic measurements, geochemistry, and inclusions, and 2) certification and tracking of individual stones through the Kimberly Process Certificate Scheme. Unfortunately, during cutting and polishing, many gemological features are obliterated and tracking individual stones through the chain of custody can be difficult. This study resulted in a highly successful method for determining provenance of cut diamonds from information in the stone itself.
A set of 30 cut diamonds from each of ten controlled localities and one set of 30 synthetic diamonds were analyzed by Laser-Induced Breakdown Spectroscopy (LIBS). The sample set (330 total diamonds) includes both kimberlite and placer diamonds from five countries and five different cratons. LIBS acquires the atomic emission spectra released from a material during laser ablation. The spectra contain information from nearly every element in the periodic table, and thus are unique chemical, or quantagenetic, signatures of the material. Spectra were analyzed using a Bayesian statistical method that compares groups of samples defined by the reported locations of the stones to clusters of samples defined by spectral similarity. Ideally, each spectral cluster coincides with a group of stones. The spectrum of each sample is compared to a set of reference spectra from each group to determine the probable provenance of the sample. The correlation between groups and clusters was excellent, with average accuracy of 98%, suggesting that diamonds from each location are spectrally similar to each other and distinct from those from other locations. This is true even for diamonds from kimberlites in close proximity to each other. Synthetic diamonds are easily distinguished from natural diamonds (100% success). Some groups of diamonds in the study are more heterogeneous than others. For instance, a placer group has five recognizable spectrally-defined sub-clusters. This work demonstrates that diamond provenance can be determined at a high level of confidence on individual cut gemstones.
Developments in FTIR spectroscopy of diamond ( part 1): nitrogen aggregation in zoned diamonds, the timing of diamond growth and the thermal history of the lithosphere.
Journal of Mining Science, Vol. 51, 4, pp. 799-810.
Russia
Spectroscopy
Abstract: Using the Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), microscopy and microhardness test methods, the change in the crystalline and chemical properties and in microhardness of rock-forming minerals of kimberlites as a result of exposure to high-power nanosecond electromagnetic pulses (HPEM) has been studied. From FTIR and XPS data the non-thermal effect of HPEM results in damage of surface microstructure of dielectric minerals due to formation of microcracks, surface breakdowns and other defects, which ensure effective weakening of rock-forming minerals and reduction in their microhardness by 40-66%.
Journal of Mining Science, Vol. 52, 2, pp. 332-340.
Technology
Spectroscopy
Abstract: The lithosphere beneath the Western Canada Sedimentary Basin has potentially undergone Precambrian subduction and collisional orogenesis, resulting in a complex network of crustal domains. To improve the understanding of its evolutionary history, we combine data from the USArray and three regional networks to invert for P-wave velocities of the upper mantle using finite-frequency tomography. Our model reveals distinct, vertically continuous high (> 1%) velocity perturbations at depths above 200 km beneath the Precambrian Buffalo Head Terrane, Hearne craton and Medicine Hat Block, which sharply contrasts with those beneath the Canadian Rockies (
Geostandards and Geoanalytical Research, in press available
Technology
spectroscopy
Abstract: A broad suite of geological materials were studied a using a handheld laser-induced breakdown spectroscopy (LIBS) instrument. Because LIBS is simultaneously sensitive to all elements, the full broadband emission spectrum recorded from a single laser shot provides a ‘chemical fingerprint’ of any material - solid, liquid or gas. The distinguishing chemical characteristics of the samples analysed were identified through principal component analysis (PCA), which demonstrates how this technique for statistical analysis can be used to identify spectral differences between similar sample types based on minor and trace constituents. Partial least squares discriminant analysis (PLSDA) was used to distinguish and classify the materials, with excellent discrimination achieved for all sample types. This study illustrates through four selected examples involving carbonate minerals and rocks, the oxide mineral pair columbite-tantalite, the silicate mineral garnet and native gold how portable, handheld LIBS analysers can be used as a tool for real-time chemical analysis under simulated field conditions for element or mineral identification plus such applications as stratigraphic correlation, provenance determination and natural resources exploration.
DiaMap: new applications for processing IR spectra of fluid rich diamonds and mapping diamonds containing isolated nitrogen ( type Ib) and boron ( type II b)
Nuclear instruments and methods in Physics Research Section B , Vol. 123 ( 1-4) pp. 579-582.
Technology
spectrometry
Abstract: A brief overview is provided of the uses of AMS in mineral analysis, emphasizing the selection of appropriate samples. Simple guidelines are given for judging the suitability of a set of samples (and the type of problem that they pose) for AMS, as opposed to other methods of in-situ analysis. Optimal interpretation of the AMS data requires that the method be employed in conjunction with a range of other types of information. These include textural and mineralogical observations obtained with petrographic or scanning electron microscopes, plus in-situ chemical data for areas of the target typically 1–250 ?m in diameter, obtained by some combination of complementary techniques, such as electron, proton or ion microprobe analysis (EPM, PIXE and SIMS, respectively).
Abstract: Samples of gilsonite from Adzharia, anthraxolite and graphite of coal from Taimyr, shungite from Karelia, and anthracite from Donbass are studied using Raman spectroscopy. Peaks at 1600 cm?1, indicating the presence of nanographite, are recorded in all samples. The anthracite sample from Donbass, 1330 cm?1, corresponds to the sp3-line of carbon hybridization conforming to a nanodiamond. It is concluded that in nature diamonds can be formed at late stages of lithogenesis (catagensis, metagenesis), and for coals, it can occur at the zeolite stage of regional metamorphism of rocks, before the green schist stage.
Progress in Earth and Planetary Science, doi.org/10.1186/ s4065-018-0203-8 17p. Open access
Mantle
spectroscopy, redox
Abstract: The behavior of COH fluids, their isotopes (hydrogen and carbon), and their interaction with magmatic liquids are at the core of understanding formation and evolution of the Earth. Experimental data are needed to aid our understanding of how COH volatiles affect rock-forming processes in the Earth’s interior. Here, I present a review of experimental data on structure of fluids and melts and an assessment of how structural factors govern hydrogen and carbon isotope partitioning within and between melts and fluids as a function of redox conditions, temperature, and pressure. The solubility of individual COH components in silicate melts can differ by several orders of magnitude and ranges from several hundred ppm to several wt%. Silicate solubility in fluid can reach several molecular at mantle temperatures and pressures. Different solubility of oxidized and reduced C-bearing species in melts reflects different solution equilibria. These equilibria are 2CH4?+?Qn?=?2CH3??+?H2O?+?Qn?+?1 and 2CO32??+?H2O?+?2Qn +?1 =?HCO3??+?2Qn, under reducing and oxidizing conditions, respectively. In the Qn-notations, the superscript, n, denotes the number of bridging oxygen in the silicate species (Q-species). The structural changes of carbon and silicate in magmatic systems (melts and fluids) with variable redox conditions result in hydrogen and carbon isotope fractionation factors between melt, fluid, and crystalline materials that depend on redox conditions and can differ significantly from 1 even at magmatic temperatures. The ?H of D/H fractionation between aqueous fluid and magma in silicate-COH systems is between ??5 and 25 kJ/mol depending on redox conditions. The ?H values for 13C/12C fractionation factors are near ??3.2 and 1 kJ/mol under oxidizing and reducing conditions, respectively. These differences are because energetics of O-D, O-H, O-13C, and O-12C bonding environments are governed by different solution mechanisms in melts and fluids. From the above data, it is suggested that (COH)-saturated partial melts in the upper mantle can have ?D values 100%, or more, lighter than coexisting silicate-saturated fluid. This effect is greater under oxidizing than under reducing conditions. Analogous relationships exist for 13C/12C. At magmatic temperatures in the Earth’s upper mantle, 13C/12C of melt in equilibrium with COH-bearing mantle in the ??7 to ??30‰ range increases with temperature from about 40 to >?100‰ and 80-120‰ under oxidizing and reducing conditions, respectively.
Novel exploration tools: using reflectance spectroscopy to detect hydration halos around kimberlites.
Vancouver Kimberlite Cluster , Oct. 3, 1p. Abstract
Mantle
spectroscopy
Abstract: Many kimberlite ore bodies are relatively small and the presence of overburden along with the complexities of interpreting geophysical data can make it challenging to intersect a kimberlite target during exploration drilling. However, the analysis of country rock drill core from the perimeter of several known kimberlites provides evidence that subtle alteration (hydration) halos around kimberlites exist, which can be detected using rapid and cost-effective spectroscopic techniques. Identification of these hydration halos, which are independent of country rock composition, may provide crucial information about the presence of undiscovered kimberlite in an exploration area, especially if kimberlite was not intersected during initial drilling. Preliminary estimates suggest that these hydration halos, which are most likely caused by kimberlite-derived hydrous fluids, can extend more than 65 meters into the country rocks, but their size strongly depends on the size of the kimberlite body. Narrow kimberlite dikes produce much smaller halos compared to large kimberlite pipes. In addition, hydration halos in carbonate rocks also appear to be smaller compared to silicate rocks.
Doklady Earth Sciences, Vol. 482, 1, pp. 1207-1211.
Russia
spectrometry
Abstract: The first chromatography-mass spectroscopy data on volatiles in diamonds synthesized in the Fe-S-C system with 5 wt % S at 1400-1450°C and 5.0-5.5 GPa indicate the evolution of volatile composition during the diamond growth and, correspondingly, the variation in redox conditions of the reaction cell. A significant role is played by various hydrocarbons (HCs) and their derivatives, the content of which can reach 87%. Our data on possible abiogenic synthesis of HCs (components of natural gas and oil) can result in global recalculations (including climate) related to the global C cycle.
Abstract: Raman spectroscopy has been foreseen as a simple and non-destructive characterization method to determine the boron concentration in heavily boron-doped diamond with metallic conductivity. However, currently available empirical studies are not fully satisfactory for enabling accurate determination of the boron concentration in diamond. Here, we study Raman spectra of epitaxial boron-doped diamond as a function of the boron concentration and the excitation wavelength. The zone center phonon and the phonon density of state maximum (at ca. 1200?cm?1) lines are analyzed using a decoupled double Fano-function. This analysis method accurately describes the observed variation of the asymmetric parameters with atomic boron concentration and the photon excitation energy and enables the determination of the atomic boron concentration from the parameters of the examined Raman lines.
Abstract: Synchrotron Mössbauer Source (SMS) spectroscopy (ESRF, Grenoble, France) has high spatial resolution (~20 microns) and has been successfully applied to measuring Fe3+ concentrations in diamond inclusions [1,2]. Over the last few decades a number of studies have been conducted on individual minerals from mantle xenoliths in order to determine the oxidation state of the upper mantle [3,4]. These studies were conducted using ?50 mg of handpicked grains as opposed to individual crystals. In this study, we applied SMS to measure ferric iron contents of individual spinels, orthopyroxenes, clinopyroxenes and garnets from 5 spinel peridotite xenoliths and 1 pyroxenite and 2 eclogite xenoliths. Spinel xenoliths derive from Kilbourne hole, Mont Briançon and Ichinomegata. Spinels from these xenoliths were previously analysed by Mössbauer spectroscopy on bulk separates [4]. Eclogite xenoliths (UAS 1055, UAS 1525) and pyroxenite xenolith (UAS 510) were obtained from Udachnaya kimberlite pipe in Siberia. In spinel peridotites measured ratios range between 0.04- 0.14 Fe3+/Fetot for Opx, 0.14-0.19 Fe3+/Fetot for Cpx and between 0.15-0.23 for Spl. These values are broadly in agreement with previous measurements [3]. In eclogites and pyroxenite, the ratios range between 0.05-0.16 for garnet and 0.07-0.17 for Cpx, showing DGrt/Cpx for Fe3+ of 0.8-1.9. Oxygen fugacities derived from the spinel-olivineorthopyroxene oxybarometer are consistent with previous results for the continental lithosphere fO2 of between -1 and +1 log units relative to the FMQ buffer [5]. Nevertheless we observe small differences between our results on individual grains and previous data on bulk separates.
Abstract: Raman spectroscopy is widely applied in metamorphic petrology and offers many opportunities for geological and tectonic research. Minimal sample preparation preserves sample integrity and microtextural information, while use with confocal microscopes allows spatial resolution down to the micrometer level. Raman spectroscopy clearly distinguishes mineral polymorphs, providing crucial constraints on metamorphic conditions, particularly ultrahigh-pressure conditions. Raman spectroscopy can also be used to monitor the structure of carbonaceous material in metamorphic rocks. Changes in structure are temperature-sensitive, so Raman spectroscopy of carbonaceous material is widely used for thermometry. Raman spectroscopy can also detect and quantify strain in micro-inclusions, offering new barometers that can be applied to understand metamorphic and tectonic processes without any assumptions about chemical equilibrium.
Abstract: Geoscientists quickly recognized the broad applicability of Raman micro-probe spectroscopy to the Earth and planetary sciences, especially after commercially built microprobe instruments became available in the early 1980s. Raman spectra are sensitive to even minor (chemical or structural) perturbations within chemical bonds in (even amorphous) solids, liquids, and gases and can, thus, help identify, characterize, and differentiate between individual minerals, fluid inclusions, glasses, carbonaceous materials, solid solution phases, strain in minerals, and dissolved species in multi-component solutions. The articles in this issue explore how Raman spectroscopy has deepened and broadened our understanding of geological and extraterrestrial materials and processes.
Diamond and Related Materials, in press available, 19p. Pdf
Global
spectroscopy
Abstract: This study covers hydrogen-rich fancy color diamonds that exhibit complex spectra from the UV all the way to the mid-IR. The diamonds with such spectra that are included here show a large range of colors from brownish yellow to brown, yellow-green to olive and gray to violet. The color origin of such diamonds has always been stated as “hydrogen-related”, without much evidence pointing towards hydrogen actually causing absorptions in the visible spectral range, but only based on their unusually high IR active hydrogen content determined via their FTIR spectra. The diamonds analyzed during this work always showed a series of absorptions in the near-infrared at 7495, 7850, 8255, and 8615 cm?1. For the first time, this here presented study shows the results of low temperature near-infrared spectroscopy performed for a series of differently colored diamonds that all showed these NIR absorptions. When measured at 77 K, it became clear that these NIR bands are actually part of an electronic optical center with ZPLs at 1329.8 to 1330.2 nm (7520-7518 cm?1)/1331.8 to 1332.2 nm (7508-7506 cm?1) and 1341 to 1341.2 nm (7457-7456 cm?1). In this paper we will refer to this defect as the "1330 nm center" (which corresponds to 7519 cm?1) for the sake of brevity. The detailed analysis of the spectra has demonstrated that the colors of diamonds that exhibit the 1330 nm center spectra are caused partially by this same center, and by complex absorption bands associated to two series of ZPLs represented by a number of sharp bands between 965 and 1001 nm, referred to as the 990 nm series in this study. Of these, the 990 nm series was found only in diamonds with significant IR active hydrogen concentrations, while the 1330 nm center was determined to be independent from the concentration of IR active hydrogen. The 1330 nm center was found in spectra lacking the 990 nm series of ZPLs, but the 990 nm series has never been found in spectra without the 1330 nm center. We are suggesting that the defects involved in these absorptions are all nickel?nitrogen-related, with the 1330 nm center lacking hydrogen while it seems reasonable to assume that the 990 nm series includes hydrogen in its structure.
MDPI Minerals, Vol. 10, 916, doi:10.2290/ min0100916, 12p. Pdf
Global
spectroscopy
Abstract: The country or mine of origin is an important economic and societal issue inherent in the diamond industry. Consumers increasingly want to know the provenance of their diamonds to ensure their purchase does not support inhumane working conditions. Governments around the world reduce the flow of conflict diamonds via paper certificates through the Kimberley Process, a United Nations mandate. However, certificates can be subject to fraud and do not provide a failsafe solution to stopping the flow of illicit diamonds. A solution tied to the diamonds themselves that can withstand the cutting and manufacturing process is required. Here, we show that multivariate analysis of LIBS (laser-induced breakdown spectroscopy) diamond spectra predicts the mine of origin at greater than 95% accuracy, distinguishes between natural and synthetic stones, and distinguishes between synthetic stones manufactured in different laboratories by different methods. Two types of spectral features, elemental emission peaks and emission clusters from C-N and C-C molecules, are significant in the analysis, indicating that the provenance signal is contained in the carbon structure itself rather than in inclusions.
Minerals MDPI, Vol. 10, 1084, doi:10.3390/ min10121084 10p. Pdf
Mantle
spectroscopy
Abstract: The composition of clinopyroxenes is indicative for chemical and physical properties of mantle substrates. In this study, we present the results of Raman spectroscopy examination of clinopyroxene inclusions in natural diamonds (n = 51) and clinopyroxenes from mantle xenoliths of peridotites and eclogites from kimberlites (n = 28). The chemical composition of studied clinopyroxenes shows wide variations indicating their origin in different mantle lithologies. All clinopyroxenes have intense Raman modes corresponding to metal-oxygen translation (~300-500 cm?1), stretching vibrations of bridging O-Si-Obr (?11~670 cm?1), and nonbridging atoms O-Si-Onbr (?16~1000 cm?1). The peak position of the stretching vibration mode (?11) for the studied clinopyroxenes varies in a wide range (23 cm?1) and generally correlates with their chemical composition and reflects the diopside-jadeite heterovalent isomorphism. These correlations may be used for rough estimation of these compounds using the non-destructive Raman spectroscopy technique.
Geostandards and Geoanalytical Research, doi:10.111/ GGR.12373. 51p. Pdf
Global
spectroscopy, mineralogy
Abstract: Photo?induced force microscopy (PiFM) is a new?frontier technique that combines the advantages of atomic force microscopy with infrared spectroscopy and allows for the simultaneous acquisition of 3D topographic data with molecular chemical information at high spatial (~ 5 nm) and spectral (~ 1 cm?1) resolution at the nanoscale. This non?destructive technique is time efficient as it requires only conventional mirror?polishing and has fast mapping rates on the order of a few minutes that allow the study of dynamic processes via time series. Here, we review the method’s historical development, working principle, data acquisition, evaluation, and provide a comparison with traditional geochemical methods. We review PiFM studies in the areas of materials science, chemistry, and biology. In addition, we provide the first applications for geochemical samples including the visualisation of faint growth zonation in zircons, the identification of fluid speciation in high?pressure experimental samples, and of nanoscale organic phases in biominerals. We demonstrate that PiFM analysis is a time? and cost?efficient technique combining high?resolution surface imaging with molecular chemical information at the nanoscale and, thus, complements and expands traditional geochemical methods.
Diamond & Related Materials, Vol. 116, 108386 10p. Pdf
Global
spectroscopy
Abstract: One of the most important parameters affecting the value of natural colorless diamonds is its light transparency, defined as its color grade. The regular range of color grades in the trade is denoted by alphabet letters in the range D-M, where D represents the best commercial quality. The color grade of diamonds is largely influenced by their nitrogen content (when nitrogen atoms substitute carbon atoms in the crystal) and can be determined from this property. Diamonds absorb electromagnetic radiation in the UV-visible as well as in the Infrared spectral range and therefore, their color grade is measured via spectroscopic light absorption in these frequency range. The electromagnetic properties of different polished diamonds having several nitrogen concentrations in the frequency range of 100-110 GHz (W band) have been studied. The results indicate that there is a good correlation between the amount of nitrogen impurities and the Free Spectral Range (FSR) parameter of a reflection signal, S11, in the antenna. From the study It is concluded that measuring the diamonds dielectric properties via spectroscopic analysis in the millimeter wavelength range, can determine the color grading. In addition, the FSR measurements were correlated well with the FTIR measurements. The methodology of the new color determination mode and a novel color estimate, based on the FSR vs the nitrogen correlation, has been tested on 26 diamonds with a success rate higher than 70%.
Abstract: The results of studying characteristics of IR and Raman spectra of a diamond plate from the Sytykan pipe with central olivine inclusions are presented. The correlation between changes in the content of nitrogen defects and the internal stress of individual diamond growth zones is provided by IR spectroscopy. The total nitrogen content as A and B1 defects has a range from 81 ppm to 1075 ppm. Area of decreased nitrogen defects concentration in the centre of the diamond plate corresponds to the local pressure around the olivine inclusion. The results of the Raman spectroscopy of this sample showed that the olivine inclusion is stressed. In this connection, the maximum shift of the most intensive bands of SiO4 stretching vibrations is ?? = 5 ± 0.09 and 4 ± 0.12 cm-1, which corresponds to the internal residual pressure in the inclusion of Pi = 1.64 ± 0.1 GPa calculated by formulas given in (Izraeli, 1999; Yasuzuka, 2009). According to Izraeli, E. S. (1999) and the obtained results of Pi the pressure of diamond crystallization Pf = 6,4 ± 0,5 GPa at the model growth temperature of 1200°C is calculated. The area of diamond and inclusion contact zone is identified (bright yellow) by the Raman mapping, it exhibits wide bands 655 - 792 cm-1, typical for non-crystalline material such as Si2O(OH)6 dimers and Si(OH)4 monomers in an aqueous fluid (Nimis et al., 2016).
Abstract: The goal of this work is to investigate the diamond collection preserved at the Natural History Museum of the University of Firenze (MSN-FI) using a multidisciplinary approach. The mixed methods combine historical research with spectroscopic techniques to gain a deeper understanding of this collection of great historical, scientific and gemmological interest. This study concerns the analysis of 61 diamonds that are relatively small in both size and weight, mostly unworked and sometimes rich in inclusions. These specimens were acquired by MSN-FI from diverse collectors and institutions from 1824 until the most recent acquisitions in the 1990s. The FTIR spectroscopy was performed on 45 specimens. The results show the physical classification of diamonds in three groups (IaAB, IaA, and IaB) and reveal the presence of hydrogen as ethylene -CH?=?CH- or vinylidene?>?C?=?CH2 group.
