Garnets Research Papers - Academia.edu (original) (raw)

Garnet-(olivine) websterite xenoliths from the lithospheric mantle of the central and northeastern parts of the Siberian Craton contain exsolution microstructures after Si-and Ti-rich precursor garnets. We petrographically, geochemically, and thermobarometrically investigated 13 such xenoliths from the Mir, Obnazhennaya, and Udachnaya kimberlite pipes. All samples contain garnet grains with needle-to lamellae-shaped precipitates (up to 3.0 vol%), including Ti-oxide and/or pyroxene. Orthopyroxene and clinopyroxene grains host oriented lamellae of complementary Ca-rich and Ca-poor pyroxene, respectively, in addition to lamellae of garnet and Ti-and/or Cr-oxides. The common exsolution lamellae assemblages in garnet and pyroxene imply that exsolution occurred during cooling from high-temperature precursors. Exsolution is unlikely to have resulted from variations in pressure, given experimental and thermodynamic constraints. Host mineral partitioning of transition metal and lanthanide elements with different diffusivities record temperatures that range between those of local geotherms and a dry pyroxenite solidus. Inferred magmatic minimum temperatures of 1500-1700 °C satisfy the physical conditions predicted from experimental studies of the solubility of excess Si and Ti in garnet. Gran-ular inclusions of all major minerals within each other imply an overlapping crystallisation history. The reconstructed compositions of the websterite whole-rocks have high MgO contents (15.7-35.7 wt%). A plot of MgO/ SiO 2 versus SiO 2 forms an array, apart from the compositions of natural websterites that formed by interaction of peridotite with basaltic or siliceous melts. The array overlaps the compositional range of komatiite flows from Commondale and Barberton, South Africa, including spinifex, massive, and cumulate subtypes of komatiites. Other major and minor element abundances and ratios of the Siberian websterite suite resemble those of South African Al-enriched komatiites and are distinct from melt-rock reaction websterites. Therefore, the mineral mi-crostructures and geochemistry of the Siberian websterites are suggestive of the former presence of a thermal anomaly. We propose that mantle plume activity or a similar form of lower-mantle ascent played a major role in stabilising cratonic nuclei before amalgamation of the present-day Siberian Craton.

- by
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- Microstructure, Petrology and Geochemistry, Mantle Petrology, Garnets
- by Noel Adams
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- Medieval Archaeology, Garnets, Garnet jewellery, Anglo Saxon, Merovingian garnet
- by Marco Aimone
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- Early Medieval Archaeology, Early Medieval Art, Garnets, The Merovingians

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

- by Lisbet Thoresen, Temecula, CA, USA
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- Gemology, Archaeometry, Garnets, Ancient Gemstones,jewelery

Researchers from different fields like archaeology, history, philology and natural sciences present their studies on ancient gemstones. Using precious minerals as an example, trade flows and production methods, but also utilisation and perception are discussed in a cross-cultural and diachronic approach.
The present volume aims at three main questions concerning gemstones in archaeological and historical contexts: »Mines and Trade«, »Gemstone Working« as well as »The Value and the Symbolic Meaning(s) of Gemstones«. This volume contains the proceedings of the conference »Gemstones in the first Millennium AD« held in autumn 2015 in Mainz, Germany, within the scope of the BMBF-funded project »Weltweites Zellwerk – Universal Framework«.

- by RGZM Verlag / publishing house and +1
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- Archaeology, Silk Road Studies, Garnets, Garnet chemistry

Outstanding garnet beads were found recently in an elite tumulus dated to the fourth century AD and located at the cemetery of Hagar el‐Beida in the Upper Nubian Nile Valley region. Whereas contacts of Northeast Africa with South Asia have just been proven through analysis of glass beads found in Nubia and dating to the time of intensive Indian Ocean trade, scientific evidence for Nubia's link with the regions to the west was lacking. Laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) was used to determine the elemental composition of three garnet beads to gain information about their type and origin. Additionally, we analyzed twelve garnets from two nearby alluvial placer deposits. While the garnet beads are inclusion‐free Cr‐poor and Ti‐rich pyropes related to alkaline mafic volcanic rocks, the local garnet deposits are shown to be inclusion‐rich almandines and thus unrelated to the investigated Nubian beads. Detailed comparison of data from Merovingian cloisonné jewellery and all known sources of the Cr‐poor and Ti‐rich pyropes shows identical ranges of elemental contents. The source of raw materials for the beads found in Nubia has been not identified with certainty yet, but sources in Portugal and Nigeria are suggested and a connection is shown to similar garnets from Merovingian contexts.

- by Joanna Then-Obłuska and +1
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- Late Antiquity, Saharan Archaeology, Nubian-Egyptian Relations, Nubia
- by Marion Sorg
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- Merovingian period, Garnets, Garnet chemistry, Garnet jewellery

Millions of tons of spent garnet, a by-product of surface treatment operations, are disposed of every year in landfills, oceans, rivers, and quarries, among others, thus causing environmental problems. The main objective of this study is to evaluate spent garnet as a sand replacement in concrete prepared with ground granulated blast furnace slag (GGBS)-based self-compacting geopolymer concrete (SCGC). Concrete mixtures containing 0%, 25%, 50%, 75% and 100% spent garnet as a replacement for river sand were prepared with a constant Liquid/Binder (L/B) mass ratio equal to 0.4. Compressive, flexural and splitting tensile strengths as well as workability tests (slump, L-box, U-box and T50) were conducted on concrete containing spent garnet. As per specification and guidelines for self-compacting concrete (EFNARC) standard, the test results showed that the concrete's workability increased with the increase of spent garnet, while all the other strength values were consistently lower than conventional concrete (SCGC) at all stages of replacement. Based on the outcomes It is recommended that spent garnet should be used in concrete as a sand replacement up to 25% to reduce environmental problems, costs and the depletion of natural resources.

- by Habeeb Lateef Muttashar Alzuabidi
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- Recycling, Geopolymer Concrete, Garnets, Green Building

РЕЗЮМЕ. Настоящата работа предоставя данни за морфологията, размера и химичният състав на гранати от метаморфната рамка на Сакарския плутон. Изследвани са образци от районите на селата Орлов дол (слюдени шисти), Хлябово (слюдени и хлоритови шисти), Орешник (слюдени шисти), Планиново (слюдени шисти и амфиболити) и Дервишка могила (слюдени шисти). Размерът на гранатовите порфиробласти варира от 0,70 до 50,10 mm. Морфологията им е представена от {110} или комбинации с {211}, в които доминираща проста форма е {110}. Имат преобладаващо алмандинов състав (Alm 69,91-78,96 mol %) с вариращо съдържание на останалите компоненти. Ореолите на разсейване на граната са изследвани по данни от Националния Геофонд. Извършен е статистически анализ на разпределението на съдържанието на граната, вероятността му за откриване в пробите и са посочени значимите статистически корелати и акорелати. Изготвени са шлихоминераложки прогнозни карти за търсене на гранатови минерализации и е изработен Фурие модел на закономерностите в разпределението им. Установява се, че граната е силно разсеян в региона, при което 24 % от гранатовите проявления в шлихоминераложките проби са привързани към рамката на Сакарския плутон и маркират ясно изразени ивици с посока СЗ-ЮИ и СИ-ЮЗ. Изявените шлихоминераложки аномалии на гранат се разполагат в ивицита Хлябово – Карабаир и източно в района на долината на р. Явуздере. ABSTRACT. The present paper provides data about morphology, size and chemical composition of garnets from the frame of Sakar pluton. The places of sampling are in the region of the villages Orlov Dol (mica schists), Hlyabovo (mica and chlorite schists), Oreschnik (mica schists), Planinovo (mica schists and amphibolites) and Dervischka Mogila (mica schists). The size of the studied garnets range from 0,70 to 60 mm. Their morphology is represented by {110} or by combinations of {110} with small {211} faces. All garnets are almandine rich (Alm 69,91-78,96 mol %) with varying amounts of the other end members. The aureols of garnet distribution have been studied on the basis of data from National Geofund. Statistical study of quantitive distribution of garnets and the probability of its finding in the probes has been presented and the significant statistical correlates and miscorrelates has been shown. The prognosticative maps are prepared in order to prospect garnet mineralization. Furrier model of the regularities in garnet distribution has been worked out. Approximately 24 % of the garnet presence in heavy concentrate probes is related to the metamorphic rim of the Sakar pluton and thus it marks clearly expressed stripes with NW-SE and NE-SW direction. The places with most abundant quantities of garnet in heavy concentrate probes аre present in the Hlyabovo – Karabair stripe and on the East in the region of the Yavuz Dere valley.

- by Oleg Vitov and +1
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- Mineralogy, Morphometry, Silicate mineralogy, Garnets

Some thirty or more years ago, a gold fitting decorated with cloisonné-work was found in Mali Mošunj in Bosnia and Herzegovina. Subsequently, it was identified as part of the scabbard of a sword. The materials used in its making are expensive and available to few, and its construction suggests it was manufactured in a specialised goldsmith’s workshop equipped and trained to work with gold, almandines and ivory(?). Rare comparative archaeological evidence classifies it among precious scabbard mouthpiece fittings which
could only have been worn by a high-ranking member of the late Roman military elite serving in Dalmatia during the “Dalmatian dynasty” of Marcellinus and Julius Nepos, or later, during the reign of Odoacer. i.e. in the last third or quarter of the fifth century. The appendix to this paper analyses data related to cloisonné on scabbard mouthpiece fittings from nineteen early Merovingian sites covered by the Beauvais-Planig type (type 2), for which a classification into subtypes 2a to 2d is proposed here.
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U Malom Mošunju u Bosni i Hercegovini nađen je prije tridesetak i više godina zlatni okov ukrašen kloazoniranjem za koji se kasnije utvrdilo da pripada koricama mača. Materijali upotrijebljeni u njegovoj izradbi skupocjeni su i dostupni malobrojnima, a tehnika izradbe upućuje na rad specijalizirane zlatarske radionice opremljene i obučene za rad sa zlatom, almandinima i bjelokosti(?). Rijetka komparativna arheološka građa svrstava ga među skupocjene okove usta korica mača kakav je o pojasu mogao nositi jedino neki visoko pozicionirani pripadnik kasnorimskodobne vojne elite službujuće u Dalmaciji u vrijeme “dalmatinske dinastije” Marcelina i Julija Nepota ili kasnije, za vladavine Odoakara, tj. u posljednjoj trećini ili posljednjoj četvrtini 5. stoljeća. U dodatku ovog rada analizirani su i podaci koji se odnose na kloazoniranje na okovima usta korica s devetnaest ranomerovinških nalazišta obuhvaćenima tipom Beauvais- Planig (tip 2), za koje je ovdje predložena klasifikacija na podtipove 2a do 2d.

- by Željko Demo
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- Garnets, Dark Ages History, Later Roman Empire, Sword

The structural and magnetic properties of Al substituted yttrium-iron garnet (Y 3 Al x Fe 5-x O 12 , x ¼ 0, 0.1, 0.2, 0.3, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6 and 1.8) ceramic powders synthesized using solution combustion method were investigated. Post combustion, the samples were calcination at 1045 C for 6 h and subsequently at 1200 C for 6 h to obtain phase-pure garnets. X-ray diffraction (XRD) results confirm the formation of garnets with Ia3d structure. The occupancy of Y 3þ ions in the dodecahedral site and the distribution of Al 3þ and Fe 3þ ions in the tetrahedral and octahedral sites in the bcc structure of the garnet were confirmed by Rietveld refinement of XRD patterns, M€ ossbauer spectroscopy and 57 Fe internal field NMR spectroscopy. For low Al content, Al 3þ ions have preference to occupy tetrahedral (T d) sites than the octahedral (O h) sites. At higher Al content the distribution of Al tends towards a ratio of 3:2 at the tet-rahedral:octahedral site. Increase in Al doping results in the decrease in the lattice parameter due to smaller size of Al 3þ as compared to Fe 3þ ion. All the studied samples show coral-network-like surface morphology. The saturation magnetization (M S) values decrease from ~26.94 emu/g to ~ 0.17 emu/g with increase in Al content from 0.0 to 1.8. Further addition of Al makes the sample paramagnetic at RT. Substitution of non-magnetic Al 3þ reduces the saturation magnetization rapidly due to the decrease in the superexchange interaction in the crystal.

- by Harish Kumar Choudhary and +1
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- Scanning Electron Microscopy, Sol-Gel Technology, Solid State NMR, Garnets

Paper presented at the 67th International Sachsensymposium in Antwerp.

We present a method to reconstruct the dehydration flux associated with garnet-forming reactions during subduction. Garnet-bearing blueschists from the island of Sifnos, Greece, in the Attic–Cycladic Blueschist Belt are used as a test case to extract information on the timescales of dehydration during subduction. We use garnet growth as a proxy for the net dehydration reaction. Thermodynamic (pseudosection) analysis of a mafic blueschist in this unit (representative of an altered basalt protolith) indicates that garnet grew via net reaction(s) of the form chlorite+chloritoid+glaucophane+phengite=garnet+pyroxene+lawsonite+ paragonite+quartz+H2O. Garnet core and rim chemistry indicates that growth began at 2.0 GPa and 460 °C and ended at 2.2 GPa and 560 °C. The stabilization of matrix lawsonite (promoted by the bulk chemical shift of the matrix due to fractionation of the garnet and its inclusions from the system) throughout garnet growth limits the amount of water liberated from the rock over this P–T span. The average stoichiometry of the garnet-forming reaction(s) indicates an average molar production ratio of garnet to water of ~ 1.0:0.7. Given the 11 vol.% garnet observed in the rock, this analysis indicates a loss of 0.3 to 0.4 wt.% H2O from the bulk rock during garnet growth. Zoned garnet geochronology from these rocks provides a constraint on the dehydration rate from this lithology during the time span of garnet growth. Two garnet grains, roughly 1.5 cm each in diameter, were microdrilled based on major element zoning contours. Three concentric growth zones were extracted from each garnet for Sm–Nd geochronology. Very low Nd concentrations in acid-cleansed garnet (0.03 to 0.09 ppm) yielded very small samples (~1 ng Nd) that were analyzed with TIMS using a NdO+ with Ta2O5 activator method. Untreated “garnet” powders rich in mineral inclusions from each garnet zone were also analyzed. The powders fall off of the garnet-matrix isochron, likely indicating age inheritance in the inclusions. Combining acid-cleansed garnet data from each garnet, multi-point garnet-matrix isochron ages of 46.50 ± 0.80 Ma for the core, 46.49 ± 0.53 Ma for the intermediate zone, and 46.46 ± 0.59 Ma for the rim were determined, indicating a brief growth duration of 0.04 Ma with an upper bound (2 SD) on growth duration of 1.0 Myr. This equates to a release of 0.3–0.4 wt.% of water due to this reaction in this lithology, and heating of 100 °C, in less than 1.0 Myr. The short time interval represents a focused, rapid pulse of dehydration and heating within the context of the overall subduction descent timescale of ~10–20 Myr.

- by Besim Dragovic and +1
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- Metamorphic Petrology, Geochronology, Radiogenic Isotope Geochemistry, Garnets

The purpose of this article is to present a preliminary overview of the workshop activities in the late 6th and 7th centuries in Gamla Uppsala, with special focus on the garnets. Our knowledge about the craft activities on this site has changed dramatically since 2010. We have moved from a situation with scattered assemblages of various craft-related items to the discovery of two actual workshops and a significant increase of craft-related objects. These results have provided us with major insights into the organization of high quality craftsmanship in an aristocratic setting and, not least, how garnets were transformed from raw material to finished stones for inlays in jewellery, weapons and riding equipment.

- by John Ljungkvist and +2
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- Early Medieval History, Garnets, Vendel period, Archaeology Of The Migration Period And The Early Middle Ages

Abrasive waterjet cutting is one of the unconventional cutting processes capable of cutting extensive range of difficult-to-cut materials. This paper assesses the impact of process parameters on surface roughness which is a significant machining performance measure in abrasive waterjet cutting of hastelloy. The experimental parameters were selected based on Taguch's design of experiments. Experiments were conducted in varying nozzle traverse speed, abrasive mass flow rate and standoff distance for cutting hastelloy using abrasive waterjet cutting process. The effects of these parameters on surface roughness have been discussed.

Purpose – To examine the mechanical properties, material composition of spent garnet as a sand replacement in high-strength concrete at room and elevated temperatures. Bonding of the concrete containing spent garnet and reinforcing rebar... more

- by Ahmad B H Kueh
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- Concrete, Garnets, Aggregate, Elevated Temperature

O 12 is a promising electrolyte for rechargeable all solid state batteries. The stability of low temperature cubic phase of garnet in argon and air was determined. The garnet stoichiometry was maintained in argon while in air lithium loss occurred. The influence of CO 2 adsorption on the structural modifications of garnet was proved. a b s t r a c t Rechargeable all solid-state lithium batteries are a promising technology for the next generation of safer batteries. In this context, strict requirements are placed on the electrolytes, among which is emerging the Li 7 La 3 Zr 2 O 12 garnet, chiefly for the relationships among synthesis conditions and phase stability. Here, the structural modifications of the low temperature (LT) Li 7 La 3 Zr 2 O 12 cubic form were investigated by using in situ X-Rays diffraction analysis. In particular, we studied the role of both temperature and atmosphere (air or argon) on phase stabilization. In argon flow, the LT phase is stable under 750 C, and it transforms into the tetragonal one at lower temperature. In air, it partially decomposes to La 2 Zr 2 O 7 due to Li loss above 250 C. ICP-OES analysis confirmed that garnet stoichiometry was maintained in argon, whereas in air lithium loss occurred. The structural transformations are driven by the CO 2 absorbed in the LT structure that can form Li 2 CO 3 and/or La 2 (CO 3) 3 so causing stoichiometry changes responsible of the structural evolution.

- by Marcella Bini
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- Garnets, XRD, Solid State Electrolyte, In-Situ XRD
- by Patrick PERIN
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- Garnets

Échanges entre le subcontinent Indien et l’Europe du Vème au VIIème siècle /// Trade between the Indian subcontinent and Europe from the 5th to the 7th c. AD /// Colloque international organisé par le Musée d'Archéologie Nationale (MAN)... more

Échanges entre le subcontinent Indien et l’Europe du Vème au VIIème siècle /// Trade between the Indian subcontinent and Europe from the 5th to the 7th c. AD ///
Colloque international organisé par le Musée d'Archéologie Nationale (MAN) et le C2RMF, Paris 22 - 23 juin 2017

- by Patricia Rifa - Abou El Nil
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- Archaeology, Late Antiquity, Merovingian period, Garnets

- by saeid baghban
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- Geology, Economic Geology, Garnets, Ore deposits

The sparse contrasting use of coloured glass inlays in the garnet jewellery of the early medieval period is a well-known and accepted aspect of the period. The glass inlays have however tended to be subject only to cursory examination in the wider study of garnet jewellery. The discovery of the Staffordshire Hoard with its many glass inlays has really highlighted this issue, particularly around the use of garnet mimicking red glasses. This brief discussion presents the prelimanary results of an investigation re-examining the relationship between the two materials on inlaid objects of three 5th-7th Century Kentish cemeteries. With the assistance of p-XRF and digital microscopy this investigation examined 267 inlays from 46 objects, identifying almost a hundred glass inlays including a number of garnet mimicking settings.

We report high-quality yttrium-iron-garnet (YIG; Y 3 Fe 5 O 12) ultrathin films grown on {111} gadolinium-gallium-garnet (GGG; Gd 3 Ga 5 O 12) substrates using RF sputtering deposition on an off-stoichiometric target and optimized thermal treatments. We measured a narrow peak-to-peak ferromagnetic resonance linewidth (H) whose minimum value was 1.9 Oe at 9.43 GHz for a 60-nm-thick YIG film. This value is comparable to the most recently published value for a YIG thin film grown by pulsed laser deposition. The temperature dependence of the H was investigated systematically, the optimal annealing condition for our growing condition was 875 • C. Structural analysis revealed that surface roughness and crystallinity played an important role in the observed H broadening. Furthermore, the thickness dependence of the H, which indicated that 60 nm thickness was optimal to obtain narrow H YIG films, was also investigated. The thickness dependence of H was understood on the basis of contributions of surface-associated magnon scattering and magnetic inhomogeneities to the H broadening. Other techniques such as transmission electron microscopy, scanning electron microscopy, and X-ray diffraction were used to study the crystalline structure of the YIG films. The high quality of the films in terms of their magnetic properties was expressed through a very low coercivity and high saturation magnetization measured using a vibration sample magnetometer.

- by Srivathsava Surabhi and +1
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- Magnetic Materials, Garnets, Rf-Magnetron Sputtering

In this study, we report the first discovery of microdiamond inclusions in kyanite–garnet schists from the Central Rhodope Mountains in Bulgaria. These inclusions occur in garnets from metapelites that are part of a meta-igneous and meta-sedimentary mélange hosted by Variscan (Hercynian) orthogneiss. Ultra-high-pressure (UHP) conditions are further supported by the presence of exsolved needles of quartz and rutile in the garnet and by geothermobarometry estimates that suggest peak metamorphic temperatures of 750–800 °C and pressures in excess of 4 GPa. The discovery of UHP conditions in the Central Rhodopes of Bulgaria compliments the well-documented evidence for such conditions in the southernmost (Greek) part of the Rhodope Massif. Dating of garnets from these UHP metapelites (Chepelare Shear Zone) using Sm–Nd geochronology indicates a Late Cretaceous age (70.5–92.7 Ma) for the UHP metamorphic event. This is significantly younger than previously reported ages and suggests that the UHP conditions are associated with the Late Mesozoic subduction of the Vardar Ocean northward beneath the Moesian platform (Europe). The present-day structure of the RM is the result of a series of subduction–exhumation events that span the Cenozoic, alongside subsequent post-orogenic extension and metamorphic core complex formation.

- by David Collings and +2
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- Garnets, UHP Metamorphism, Rhodope geology, Sm-Nd Dating
- by Alexandra Hilgner and +1
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- Archaeology, Archaeometry, Byzantine Archaeology, Merovingian period

Abstract. The garnet bearing two-mica schists from the metamorphic frame of the Sakar Pluton are investigated. As a result of this study the mineral paragenesses are determined and chemical composition and peculiarities of the rock-forming minerals are defined. The minerals from the studied rocks from the areas of villages Orlov Dol, Hlybovo and Planinovo are separated in the three metamorphic paragenesses(pre-, syn- and postkynematic), from the region of Dervishka mogila – in syn- and postkynematic and southern of the village Oreshnik – synkinematic with two generations. Investigated main rock minerals are garnet with predominant almandine composition; white mica – phengite with paragonite component and paragonite; biotite; staurolite; feldpars and chlorite.
Key words: metapelites, garnet, staurolite, pre-, syn-, postkynematic paragenesses, Sakar

- by Nikoleta Tzankova
- •
- Mineralogy, Metamorphic Petrology, Rock forming Minerals, Garnets
- by Ivan Savov
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- Geology, Geochemistry, Geophysics, Mineralogy

Inatex 2016 University Technology Maaysia

In this paper, a novel fiber-based magnetooptic (MO) latching circuit using a bismuth-substituted yttrium iron garnet (Bi:YIG) is presented. Experimentation shows that nearly 90° of rotation of the state of polarization of incident light occurs between material latching states upon application of an external magnetic field greater than 500 G. This amount of rotation is enough to cause sufficient routing at the output of an optical interferometer of Sagnac configuration, which is presented in this paper. Due to the high coercivity of the Bi:YIG, the material remains in its magnetized state for very long periods of time and is thus latched. Reversing
the applied magnetic field changes the state of the material, unlatching it. This capability has great importance for nonreciprocal all-optical devices requiring low power operation. In addition, having such control of the state of the nonreciprocal elements can allow for a wider diversification of small-scale and large-scale optical network design. A discussion of the experimental setup, the resulting measurement data, and its implication for future low power applications is presented.

- by Prabesh Dulal
- •
- Fiber Optics, Garnets, Magneto-optics, All Optical Switch

Nineteen single-grain detrital garnet ages from a tributary to the French Broad River (North Carolina, USA) establish a novel approach to Sm-Nd detrital garnet geochronology wherein the equilibrium bulk-rock composition lost during weathering and transport is replaced with the composition of inclusions leached from within each garnet grain. Detrital garnet ages were compared to published detrital zircon and monazite ages from the same river tributary system. Results show that 87% of the zircons have inherited Proterozoic ages; only zircon rims give Paleozoic ages. Monazites are exclusively Ordovician (weighted average: 460.9 ± 3.0 Ma). Our new detrital garnet ages (and the detrital zircon rims) record younger ages spanning the Late Ordovician to Early Devonian, likely reflecting prolonged metamorphic heating. The weighted average age of the detrital garnet population is Silu-rian (430.1 ± 7.2 Ma). Statistical tests confirm that the garnet population is younger than the monazite. The new detrital garnet ages illuminate a previously uninterpreted Silurian tectonometamorphic signal in this region. INTRODUCTION Garnet's resilience as a moderately to highly stable phase during weathering, transport, and deposition makes it a common component of clastic sediments and sedimentary rocks with metamorphic source terranes (Morton and Halls-worth, 1999). Detrital garnet has been used as a provenance tool but is limited in its full application potential without a robust method to determine the detrital garnet's age. Garnet's common growth as a rock-forming mineral across a wide range of pressures and temperatures, clear ties to prograde metamorphism, and utility in geo-thermobarometry (Baxter et al., 2017) also make determination of detrital garnet ages desirable, especially if primary metamorphic source out-crops are inaccessible or eroded. Furthermore, single-grain detrital garnet ages provide a method for investigating regional, catchment-scale metamorphic timing using a rock-forming index mineral without laborious outcrop sampling.

In this work, we have investigated the bismuth-substituted yttrium iron garnet (Bi-YIG) thin films prepared on glass substrate by modified metal-organic decomposition method. Real-time Faraday rotation spectrometer was used to characterize the magneto-optical properties of Bi-YIG films. The reliability of the measurement system and optimized analyzer setup was confirmed by comparing the Jones matrix calculations and measured results. The effect of annealing condition on the structural, magnetic and magneto-optical properties was investigated. A clear garnet-phase without secondary phase was observed for the Bi-YIG films annealed above 800°C. Faraday rotation spectra of these films reveal the correlation between their crystallinity and magneto-optical properties. The highest Faraday rotation angle of −3.1°/μm was achieved for 800°C annealed sample. Simultaneous evaluation of real-time Faraday rotation spectra and the corresponding hysteresis loops can establish a path for the application of time-resolved magneto-optical spectroscopic analysis of magnetic thin films.

- by Srivathsava Surabhi
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- Spectroscopy, Garnets

Sustainable Construction Materials
Recycled Spent Garnet

- by Michał Borowski
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- Mineralogy, Garnets, Ultramafites and associated mineralisation, Serpentinites

Abstract Garnet–(olivine) websterite xenoliths from the lithospheric mantle of the central and northeastern parts of the Siberian Craton contain exsolution microstructures after Si- and Ti-rich precursor garnets. We petrographically, geochemically, and thermobarometrically investigated 13 such xenoliths from the Mir, Obnazhennaya, and Udachnaya kimberlite pipes. All samples contain garnet grains with needle- to lamellae-shaped precipitates (up to 3.0 vol%), including Ti-oxide and/or pyroxene. Orthopyroxene and clinopyroxene grains host oriented lamellae of complementary Ca-rich and Ca-poor pyroxene, respectively, in addition to lamellae of garnet and Ti- and/or Cr-oxides. The common exsolution lamellae assemblages in garnet and pyroxene imply that exsolution occurred during cooling from high-temperature precursors. Exsolution is unlikely to have resulted from variations in pressure, given experimental and thermodynamic constraints. Host mineral partitioning of transition metal and lanthanide elements with different diffusivities record temperatures that range between those of local geotherms and a dry pyroxenite solidus. Inferred magmatic minimum temperatures of 1500–1700 °C satisfy the physical conditions predicted from experimental studies of the solubility of excess Si and Ti in garnet. Granular inclusions of all major minerals within each other imply an overlapping crystallisation history. The reconstructed compositions of the websterite whole-rocks have high MgO contents (15.7–35.7 wt%). A plot of MgO/SiO2 versus SiO2 forms an array, apart from the compositions of natural websterites that formed by interaction of peridotite with basaltic or siliceous melts. The array overlaps the compositional range of komatiite flows from Commondale and Barberton, South Africa, including spinifex, massive, and cumulate subtypes of komatiites. Other major and minor element abundances and ratios of the Siberian websterite suite resemble those of South African Al-enriched komatiites and are distinct from melt–rock reaction websterites. Therefore, the mineral microstructures and geochemistry of the Siberian websterites are suggestive of the former presence of a thermal anomaly. We propose that mantle plume activity or a similar form of lower-mantle ascent played a major role in stabilising cratonic nuclei before amalgamation of the present-day Siberian Craton.

- by Taisia Alifirova
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- Geology, Geochemistry, Geophysics, Microstructure
- by Paul Giesting
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- Earth Sciences, Raman Spectroscopy, Mantle Petrology, Entropy
- by Nikoleta Tzankova
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- Mineralogy, Applied Waterjet Technology, Mineral Processing, Garnets

Graphical abstract Abstract This paper represents the effects of using waste generated from palm oil industries like ash, shell and fibre on the engineering properties of mortar. Palm Oil Fuel Ash (POFA) was used as cement replacement up to 60% and Oil Palm Kernel Shell (OPKS) as sand replacement in mortar mixture. The Oil Palm Fibre was added to increase the strengthening performance of mortar. The method used to find the water binder ratio was by trial and error method with 1:3 ratio of cement to sand. The cubes size of 70mm x 70mm x 70mm, beams size of 40mm x 40mm x 160mm, and cylinders size of 70mm diameter and 150mm height, were cast and tested for compressive strength, flexural strength and splitting tensile strengths of mortar. Samples were cured in water before testing it at 7, 28, and 60 days. Also, the water absorption of mortar was tested at the age of 28 days. The results showed that oil palm fibre provided more advantages and increase the strength properties especially in the flexural and tensile strength. The addition of Oil Palm Kernel Shell reduced the density of mortar and it can be used for lightweight application. The test results also showed that as the POFA ratio increased, the compressive strength of mortar decreased. However, as OPKS ratio increased, the density was found to be decreased. The mix proportions using 60% POFA and 20% OPKS was considered as the optimum mix design. The mortar showed optimum strength at 9% with the addition of fibre. Abstrak Kertas kerja ini membentangkan kesan penggunaan sisa daripada industri minyak sawit termasuk abu, tempurung dan gentian terhadap ciri-ciri kejuruteraan mortar. Abu terbang kelapa kelapa sawit (POFA) digunakan sebagai pengganti simen sehingga 60% manakala tempurung sawit (OPKS) digunakan sebagai pengganti pasir dalam campuran mortar. Gentian kelapa sawit ditambah untuk meningkatkan prestasi kekuatan mortar. Kaedah yang digunakan untuk mencari nisbah pengikat kepada air adalah secara cuba jaya dengan nisbah simen kepada pasir, 1:3. Kiub bersaiz 70mm x 70mm x 70mm, prisma bersaiz 40mm x 40mm x 160mm dan silinder dengan saiz diameter 70mm and tinggi 150mm dibuat dan diuji bagi kekuatan mampatan, kekuatan lenturan, dan kekuatan tegangan pemisahan mortar. Sampel-sampel diawet dalam air sebelum diuji pada hari ke 7, 28 dan 60. Serapan air pada

Abstract
Deviations from the ideal rhombododecahedron are observed in the metamorphic rocks from the frame of the Sakar pluton. They are presented in elongation of the crystals along one of the axes G4 or G3, around which the elongated in the same direction quadrangular rhombohedral or hexahedral faces are developed. The point group of the visual symmetry of the crystals is interpreted in terms of the Curie symmetry-dissymmetry principle. The influence of the orientated pressure, active perpendicular to the one of the axes of the symmetry is supposed for the main factor, which has provoked the anisotropical conditions of the garnet crystal growth.
Key words: garnet, morphology, real rhombododecahedron, Sakar

- by Nikoleta Tzankova
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- Mineralogy, Crystallography, Metamorphic Petrology, Morphological evolution

A quantitative assessment of metamorphic chemical equilibrium derived from correlation of spessartine content and garnet Sm–Nd ages suggests that major element matrix equilibrium was maintained (to a first order) throughout a ca. 40 cm-wide rock sample during garnet growth; however cm-scale Sm–Nd isotopic heterogene- ity limits the Sm–Nd age precision required to evaluate more subtle age differences within individual garnet crystals. Central wafers from 1–3 cm diameter garnet grains within a 1.21 × 104 cm3 block of pelitic schist were used to document concentric growth zoning of major elements, with decreasing Mn and Ca and increasing Fe and Mg from cores to rims. Garnets also preserve growth zoning patterns for HREE and MREE and show evidence for resorption and partial recrystallization of the outermost rims. Similar garnet core compositions and identical garnet rim compositions for large like sized porphyroblasts throughout the sample suggest that garnet growth occurred at near equilibrium P–T–X conditions for major elements over the sample volume. Comparison of 28 rock Sm–Nd isotope values from the sample indicates substantial cm-scale heterogeneity, which precludes meaningful use of local garnet rock isotope pairs for isochron age calculation. Therefore, Sm–Nd isotopic compositions of thirty-eight concentric core to rim garnet segments from ten large (1–3 cm) garnets and two small (1–4 mm) bulk garnets, with narrow ranges of Mn content, are paired with sixteen matrix/whole-rock Sm–Nd isotopic compositions collected over the rock volume to define a range of isochron ages from 383.1 ± 6.8 Ma to 324.5 ± 3.3 Ma. Four of the garnets have anomalously young rims that likely result from post-growth alteration. Chlorite, quartz, and xenotime haloes around garnet suggest that anomalously young garnet rim ages reflect post-growth resorption/recrystallization effects. Excluding these young rims yields a range of ages from 383.1 ± 6.8 (oldest core) to 374.9 ± 1.8 Ma (youngest rim). Sm–Nd age precisions N 1.5 m.y. (and high MSWD) result primarily from isotopic heterogeneity in the finely layered metasedimentary rock matrix. However, garnet cores with high Mn (n = 7), mantles with intermediate Mn (n = 14), and rims with low Mn (n = 8; including the 2 smaller bulk garnet analyses), define three distinct multi-grain isochrons of 380.3 ± 2.0 Ma (n = 23, MSWD = 14), 377.3 ± 1.4 Ma (n = 30, MSWD = 18), and 376.5 ± 1.0 Ma (n = 24, MSWD = 18), respectively, yielding an average garnet growth duration of 3.8 ± 2.2 m.y. These three composite Mn-age zones define a Mn vs. age relationship that reflects depletion of Mn in the rock matrix as it is sequestered by growing garnet. Correlation of garnet major element compositions throughout the sample suggests that major element matrix equilibrium was generally maintained (to a first order) throughout the ca. 4 m.y. duration of garnet growth.

- by Besim Dragovic and +1
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- Metamorphic Petrology, Geochronology, Petrology and Geochemistry, Radiogenic Isotope Geochemistry

In 2013, some dark red crystals were found in the southern mountains of the Negev Desert region near Eilat, Israel. This area is known to be rich in granite- and quartz-bearing rocks. Around 500 g of samples were collected during a two-month period, and a few were fashioned as cabochons, the biggest weighing 1.54 ct.
Gemmological testing was performed on seven rough samples and on one partially polished piece. They ranged from 0.38 to 0.67 g, averaging slightly over 0.4 g and measuring 4.3–7.8 mm in maximum dimension.

- by Guy Borenstein
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- Gemology, Geology, Mineralogy, Garnets

The chemistry of garnet can provide clues to the formation of skarn deposits. The chemical analyses of garnets from the Astamal Fe-LREE distal skarn deposit were completed using an electron probe micro-analyzer. The three types of garnet were identiﬁed in the Astamal skarn are: (I) euhedral coarse-grained isotropic garnets
(10–30 mm across), which are strongly altered to epidote, calcite and quartz in their rim and core, with intense pervasive retrograde alteration and little variation in the overall composition (Adr94.3–84.4 Grs8.5–2.7 Alm1.9–0.2) (garnet I); (II) anhedral to subhedral brecciated isotropic garnets (5–10 mm across) with minor alteration, a
narrow compositional range along the growth lines (Adr82–65.4 Grs21.9–11.7 Alm11.1–2.4) and relatively high Cu (up to 1997 ppm) and Ni (up to 1283 ppm) (garnet II); and (III) subhedral coarser grained garnets (N30 mm across) with moderate alteration, weak diffusion and irregular zoning of discrete grossular-almandine-rich do-mains (Adr84.2–48.8 Grs32.4–7.6 Alm19.9–3.5) (garnet III). In the third type, the almandine content increases with increasing grossular/andradite ratio and increasing substitutions of Al for Fe3+.
Almost all three garnet types have been replaced by ﬁne-grained, dark-brown allanite that is typically disseminated and has the same relief as andradite. The Cu content increases while Ni content decreases slightly towards the rim of garnet II and garnet III. Copper in garnet II is positively correlated with increasing almandine content and decreasing andradite content, indicating that the almandine structure, containing relatively more Fe2+,is
more suitable than andradite and grossular to host divalent cations such as Cu2+. Nickel in garnet II is positively
correlated with increasing andradite content, total Fe, and decreasing almandine content. This is because Ni
2+
substitutes for Fe3+ in the Y (octahedral) position. There are unusual discrete grossular-almandine rich domains
within andraditic garnet III, indicating the low diffusivity of Ca compared to Fe at high temperatures

- by saeid baghban
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- Geology, Mineralogy, Economic Geology, Mineral Chemistry

Abstract. This study provides data about the chemical composition of garnet and associated minerals from the quartz-mica schists occurring to the south of the village Oreschnik, Sakar Mountain, and coustrains the P - T conditions of metamorphism. The chemical composition of the following minerals have been studied by electron microprobe: garnet, biotite, staurolite, white mica, chlorite, plagioclase. The metamorphic grade is of lower amphibolite facies. The P - T estimate for a staurolite - garnet - white mica - biotite - chlorite - plagioclase schist is T = 6160 C, σ (T) = 21 and P = 7,8 kbar, σ (P) = 1.3.
Key words: garnet, amphibolite facies, metamorphism, Sakar Mountain.

- by Nikoleta Tzankova
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- Mineralogy, Crystallography, Metamorphic Petrology, Garnets

- by Albert Gilg
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- Archaeology, Geology, Geochemistry, Late Antiquity

The Saheb Fe (Cu) skarn deposit is located along the northwestern end of the Sanandaj-Sirjan Zone. This deposit occurs over an approximately 2 km distance along the contact zone between the Upper Cretaceous causative granite and the Upper Permian calcareous host rock, with several iron orebodies occurring as high-grade lenticular massive magnetite bodies (with a length of up to 90 m and a width of 25 m). Following the formation of pyroxene hornfels facies, four main stages of skarn formation have been recognized: (I) early prograde stage (type I garnet + clinopyroxene + olivine): fluid inclusions in the type I garnet yielded a high temperature and salinity (average of 506 °C and 57 wt% NaCl equiv.), which may represent the composition of initial magmatic fluids. Higher salinities at this early stage can be associated with orthomagmatic exsolution. (II) late prograde stage (type II and III garnets ± clinopyroxene ± disseminated magnetite): the coexistence of vapour-rich and halite-be...

- by saeid baghban
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- Geology, Geochemistry, Chemistry, Economic Geology
- by MANI MINA
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- Engineering, Fiber Optics, Garnets, Physical sciences