Michael S. Krzemnicki

Michael S. Krzemnicki
University of Basel | UNIBAS · Division of Geosciences

PhD

About

95
Publications
63,407
Reads
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1,095
Citations
Citations since 2017
43 Research Items
352 Citations
20172018201920202021202220230204060
20172018201920202021202220230204060
20172018201920202021202220230204060
20172018201920202021202220230204060

Publications

Publications (95)
Article
Full-text available
Demantoid from Kerman Province in south-east Iran was investigated using microscopy, spectroscopy (optical absorption, FTIR and Raman), chemical analysis (EDXRF and LA-ICP-TOF-MS) and magnetic susceptibility measurements. The samples were transparent to semi-transparent and commonly contained acicular chrysotile inclusions. Their spectroscopic and...
Article
The Mogok Metamorphic Belt (MMB) of Myanmar formed during the Paleogene collision between the West Burma block and the Shan-Thai block. The MMB is mainly composed of medium to high-grade metamorphic marble, calc-silicate rocks, gneiss, quartzite, peridotite and igneous rocks such as granite, syenite and gabbro. The Mogok area in the central part of...
Article
Full-text available
The production and trade of objects manufactured from the skeletal axis of coralid precious corals is a historically, culturally and economically important global industry. Coralids are members of the diverse Coralliidae family, which contains several species complexes and morphospecies. For most precious coral found in the jewelry trade, the color...
Conference Paper
Full-text available
Biotite-rich quartzites originating from the conjunction of Kunene River and Marienfluss as well as biotite schists from the Hartmann Mountains (Namibia) host up to cm-sized, mostly euhedral gem-quality spessartine crystals. Garnet compositions from 5 samples were investigated by means of quantitative electron microprobe element maps (Donovan et al...
Article
Full-text available
In this study, zircon inclusions in selected 115 unheated sapphires originating from metamorphic deposits were studied by confocal micro‐Raman spectroscopy. By comparing Raman features of zircon inclusions in gem‐quality sapphires from Myanmar, India (Kashmir), Sri Lanka, and Madagascar, it could be established that those of younger age (sapphires...
Article
Full-text available
In recent years, multi-element chemical analysis has been applied to a broad range of solid samples in mineralogy, geology, environmental science, biology and beyond. In this study, we present a quantification method for multi-element composition of minerals and a statistical method to investigate chemical similarity among samples. We obtain almost...
Article
Twenty-one items sold as mammoth ivory in China were submitted to the Zurich Institute of Forensic Medicine (University of Zurich, Switzerland) and SSEF for testing. The aim of this case study was to identify these samples using macroscopic morphological diagnostics, microscopic examination, FTIR spectroscopy, trace-element analysis and additional...
Article
Full-text available
Precious coral species have been used to produce jewelry and ornaments since antiquity. Due to the high value and demand for corals, some coral beds have been heavily fished over past centuries. Fishing and international trade regulations were put in place to regulate fishing practices in recent decades. To this date, the control of precious coral...
Article
Full-text available
The Mogok area in Myanmar (Burma) is known since historic times as a source for some of the finest rubies and spinels in the world. In this study, we focus on in-situ U–Pb geochronological analyses of zircon and zirconolite, either present as inclusions in gem-quality ruby and spinel or as accessory minerals in ruby- and spinel-bearing marble and a...
Conference Paper
Full-text available
Granitic pegmatites from the Borborema province in the state of Rio Grande do Norte in northeastern Brazil are amongst the most essential sources of tantalum, beryllium and gemstones, such as "Paraíba-type" tourmaline. According to LA-ICP-TOF-MS analysis and subsequent geochronological investigation performed on zircon, the genesis of the LCT-type...
Preprint
Full-text available
Precious coral species have been used to produce jewelry and ornaments since antiquity. Due to the high prices at which corals are traded, coral beds have been heavily fished. Hence, fishing and international trade regulations were put in place. However, poaching remains extensive and mislabeling of products is common. To this date, the control of...
Article
Full-text available
Mineral inclusions within 100 gem-quality spinels from both primary marble and secondary alluvial mining sites within Myanmar's Mogok Valley were analysed using Raman microspectroscopy and scanning electron microscopy (including backscattered-electron imaging and energy-dispersive spectroscopy). The samples ranged from pink to red, orangey pink to...
Poster
Full-text available
The Mogok area within the Mogok Metamorphic Belt (MMB) in Myanmar is famous worldwide for its high quality ruby and spinel deposits. Although MMB has been studied extensively in terms of petrography, geochronology and tectonics, only very limited data so far have been reported on U-Pb ages of zircon specifically from the Mogok area, which is a sign...
Poster
Full-text available
Gallium (Ga) is an important element for origin determina on of sapphires, therefore its accurate quan fica on is necessary. However, o en both Ga isotopes are interfered by doubly charged ions, e.g. Ba, Ce or Nd. Since mass resolving power of LA-ICP-TOF-MS is more than 2500 for middle masses, which is be er than that of Quadrupole-MS unit masses,...
Article
Full-text available
This preliminary study focuses on using secondary ion mass spectrometry (SIMS) to measure relative carbon isotope ratios for natural and synthetic diamonds (i.e. those grown by both chemical vapour deposition [CVD] and high-pressure, high-temperature [HPHT] techniques). The synthetic diamonds (of both CVD and HPHT origin) had significantly lower re...
Article
Full-text available
Non-destructive imaging of the internal structures of pearls has so far been mainly based on X-ray imaging methods. As organic matter is almost transparent to X-rays, the identification of some structures can be difficult. This study shows that neutron imaging can be a helpful complementary method to visualize structures inside pearls beyond standa...
Article
Full-text available
This article reviews the extraction of DNA (deoxyribonucleic acid) from biogenic gem materials (pearls, corals and ivory) for determining species identification and geographic/genetic origin. We describe recent developments in the methodology adapted for gem samples that is minimally destructive, as well as the successful DNA fingerprinting of cult...
Article
Full-text available
Recent developments have brought due diligence, along with tracking and traceability, to the forefront of discussions and requirements in the diamond, coloured stone and pearl industries. This is a result of consumer demands for detailed information on the provenance of gems, banking requirements aiming to reduce risk, industry and company initiati...
Article
After the October 2016 discovery of a new gem deposit at Bemainty near Ambaton- drazaka, Madagascar, a number of sapphires with padparadscha-like colour entered the trade. However, most of these stones were found to have unstable colour, which changes from pinkish orange to more-or-less pure pink after a few weeks in daylight. In this study, the au...
Article
Full-text available
Gemmology deals with the characterization of coloured stones, diamonds and pearls used in the jewellery sector. As the investigated objects are in general rather valuable, a large variety of non-destructive testing methods (e.g. X-ray luminescence, X-ray tomography, UV/VIS spectroscopy, etc.) is routinely used for their inspection and characterisat...
Presentation
The Mogok Stone Tract is mainly composed of high-grade metamorphic rocks such as marbles, calc-silicate rocks, gneisses, peridotites and igneous rocks such as granites, syenites and gabbros, etc. Furthermore, the Mogok Stone Tract is eminent for its finest quality gemstones like rubies, sapphires, spinels and others semi-precious gemstones. This st...
Presentation
Full-text available
The Mogok Stone Tract is mainly composed of high-grade metamorphic rocks such as marbles, calc-silicate rocks, gneisses, peridotites and igneous rocks such as granites, syenites and gabbros, etc. Furthermore, the Mogok Stone Tract is eminent for its finest quality gemstones like rubies, sapphires, spinels and others semi-precious gemstones. This st...
Conference Paper
Full-text available
Petrographic, petrologic and geochemical investigations on Cr-jadeite rocks from Kenterlau-Itmurundy near Lake Balkhash (Kazakhstan) reveal five different rock groups. Jadeitites show irregular, medium-grained white sections made up of decussate jadeite crystals and fine-grained sections made up of aligned Cr-jadeite. Omphacite jadeitites show a ho...
Article
Full-text available
Fake Pearls Made from Tridacna gigas Shells Michael S. Krzemnicki and Laurent E. Cartier  Five non-nacreous ‘pearls’ that allegedly came from Tridacna gigas (giant clams) were studied for this report. Our observations revealed that none of them were pearls, but instead they had been manufactured from Tridacna 􏰀􏰁􏰂􏰃􏰄􏰅...
Article
Full-text available
In the last few weeks, the Swiss Gemmological Institute SSEF analysed an important number of sapphires from a new deposit at Bemainty, near the small town of Ambatondrazaka in Madagascar, which were submitted to us by several reliable independent sources. This new gem-rush in Madagascar has produced in the last few months an impressive amount of sa...
Article
Full-text available
The separation of natural from cultured pearls is mainly based on the interpretation of their internal structures, which traditionally have been visualized by X-radiography and more recently by X-ray computed microtomography (micro- CT). In this study, the authors present a new analytical approach using a grating interferometer, which simultaneousl...
Article
Full-text available
The 10th-century Cirebon shipwreck was discovered in 2003 in Indonesian waters. The excavation yielded an incredible array of archaeological finds, which included pearls and jewellery. Radiocarbon dating of the pearls agrees with the age of the shipwreck, which previously was inferred using recovered coins and ceramics. As such, these are some of t...
Article
Full-text available
GemTOF, installed at the Swiss Gemmological Institute SSEF, is a next-generation chemical analysis technique for gemmology: laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOF-MS). The system enables full elemental mass-spectrum acquisition at an ultra-high acquisition speed. Nearly all elements in the periodic ta...
Article
In this study, X-ray phase contrast imaging with a grating interferometer is applied on pearls for the first time in order to distinguish natural pearls from cultured pearls. Traditionally, this separation is mainly based on X-ray radiography. In order to visualize the internal structure of pearls we used a custom-made grating interferometer setup...
Article
Full-text available
Multiphase inclusions developed in the form of nail-head spicules in a colourless chrysoberyl crystal from Myanmar were examined by optical means and by Raman microspectroscopy. The growth tubes of the multiphase inclusions contain CO2, and the grains attached to the ends of these tubes are most likely chrysoberyl crystals (based on Raman spectra a...
Article
Full-text available
We report the first successful extraction of oyster DNA from a pearl and use it to identify the source oyster species for the three major pearl-producing oyster species Pinctada margaritifera, P. maxima and P. radiata. Both mitochondrial and nuclear gene fragments could be PCR-amplified and sequenced. A polymerase chain reaction-restriction fragmen...
Article
Full-text available
Cultured pearls can be produced both with and without a nucleus. Marine pearl oysters that produce Akoya, South Sea and Tahitian cultured pearls typically use nuclei for their pearl products. The nucleus material used for these beaded cultured pearls is traditionally from freshwater Mississippi mussels. In recent years, there have been a number of...
Article
Full-text available
For this radiocarbon study, 7 saltwater pearls and 3 shells from pearl oysters have been analyzed. The declared ages of the samples range from the mid-19th century to very recent formations. The analyzed data show the potential of the bomb peak time marker to provide additional information when testing pearls. The analyzed pearls could be distinctl...
Article
For this radiocarbon study, 7 saltwater pearls and 3 shells from pearl oysters have been analyzed. The declared ages of the samples range from the mid-19th century to very recent formations. The analyzed data show the potential of the bomb peak time marker to provide additional information when testing pearls. The analyzed pearls could be distinctl...
Article
Full-text available
In the mid-1990s, V-bearing synthetic chrysoberyl was grown by Kyocera Corporation as a synthetic counterpart to material discovered at Tunduru, Tanzania. Shown here are a 1.53 ct V-bearing chrysoberyl from Tunduru (top) and a 1.06 ct synthetic chrysoberyl grown by Kyocera (bottom, 7.0×5.0 mm). Photo by K. Schmetzer. Abstract: Mineralogical and gem...
Article
Full-text available
Cu(Al,Fe 3+) 6 (PO 4) 4 (OH) 8 • 4H 2 O, has been known since prehistoric times. It has been widely used in jewelry in the Middle East (Egypt and Persia), the Far East (Tibet, Mongolia, and China), and by native North Americans (Ahmed, 1999; Chalker et al., 2004). Yet turquoise was once very fashionable in Europe, especially during the 18th and 19t...
Article
Full-text available
X-ray computed microtomography reveals the internal features of pearls with great detail. This method is useful for identifying some of the natural or cultured pearls that are difficult to separate using traditional X-radiography. The long measurement time, the cost of the instrumentation, and the fact only one pearl at a time can be imaged are som...
Article
Full-text available
The distinction of natural from cultured pearls traditionally has been based on X-radiography. X-ray computed microtomography (μ-CT) has recently been applied to gain more insight into pearl structures. Using this technique, this article presents features observed in a selection of natural pearls and beaded and non-beaded cultured pearls. Based on...
Article
Full-text available
Following our recent press release on beadless cultured pearls (also called "Keshi" in the trade, we received many positive reactions from the trade. As there were also questions about beaded cultured pearls, we would like to inform the trade, that developments in pearl cultivation is not only restricted to the beadless cultured pearls ("Keshi"), b...
Article
Full-text available
A range of different materials has already been used as cores in beaded cultured pearls, and now two new alternative options, baroque shaped shell beads and Chinese freshwater cultured pearls, are being used. Experiments with beads of the latter, approximately 6.5 mm across, have been carried out with marine Pinctada maxima and Pinctada margaritife...
Article
Full-text available
During and after the Hong Kong Jewellery Fair in Sep- tember the SSEF Swiss Gemmological Institute has re- ceived several red spinels for testing, which were found to be flux synthetic spinels. These spinels apparently have been offered in Bangkok in the last few weeks. Flux synthetic spinels are not a new issue. Actually, Nas- sau describes in his...
Poster
Full-text available
Light elements such as boron, lithium, and beryllium and even Na and Mg at low ppm levels were so far not easy to measure. As the light elements may play an important role in treatment detection and in origin determination of gemstones, we have analysed various gemstones with LIBS for these light elements. Characteristic emission signals of boron (...
Conference Paper
Full-text available
The authors recently examined gem corundum from an alluvial deposit on the South Island of New Zealand. The water-worn pebbles (see figure) were found close to Dunedin, during the reworking of an old gold mining area. Thirty samples were studied, ranging from approximately 3 to 8 mm. The 26 rough samples were transparent to translucent pink (18), t...
Article
Full-text available
This article describes the first application of laser-induced breakdown spectroscopy (LIBS) to gemology. So far, the detection of Be-diffused sapphire and ruby has been based on LA-ICP-MS or SIMS, neither of which is readily available to most laboratories. In this study, we use LIBS to detect beryllium in corundum at very low concentrations (down t...
Article
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Small emeralds discovered recently in the Binntal, Valais (Switzerland)
Article
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Study on Cs-rich beryl before this material was identified as a new mineral Pezzottaite Quite saturated pink beryl of Madagascar and Afghanistan are described. They display densities between 2.91 and 3.10 g/cm3 and RI values up to 1.608 (ne) and 1.615 (no) which exceed the values reported so far in the literature. Chemical analyses reveal very hig...