Garnets

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.

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.

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.

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.

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Im frühen Mittelalter treten häufig granatverzierte Objekte mit Einlagen aus einem weißen bis grünbläulich verfärbten Material auf, dem bisher in der Forschung relativ wenig Aufmerksamkeit geschenkt worden ist. Im vorliegenden Beitrag wird der aktuelle Wissensstand zusammengefasst und anhand einiger untersuchten Objekte erörtert, welche naturwissenschaftlichen Methoden zur Bestimmung dieser Einlagen geeignet scheinen. Neben einer kurzen Erläuterung der verschiedenen analytischen Methoden werden in diesem Beitrag auch die wichtigsten mineralischen Komponenten vorgestellt, die als Einlagenmaterial Verwendung finden können.


Abstract:
Archaeometric analyses of white inlays in early medieval garnet jewellery.


Garnet decorated objects in the early Middle Ages often have also inlays made from a white or whitish material, which is not well analyzed, yet. Using the example of several currently analyzed objects it is discussed which method seems most suitable. Different analytical methods are presented as well as the current state of knowledge and the most common mineral elements used as inlay material.


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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 is investigated. Moreover, the optimum thickness of concrete cover subjected to elevated temperatures is investigated.

Design/methodology/approach – First, the plain spent garnet was physically, chemically and thermally studied. Then, a series of concrete specimens with 0, 20, 40, 60, 80 and 100 percent of spent garnet
were prepared to determine the optimum percentage of spent garnet. Finally, the physical and mechanical behaviours of concrete specimens and effects of cover thickness on steel rebar when subjected to elevated
temperature of 200°C, 400°C, 600°C and 800°C for 1 h were studied.

Findings – Spent garnet was thermally stable compared to river sand. Mechanical properties were found to be optimal for concrete with 40% spent garnet replacement. Physically, spent garnet concrete changed colour to brown at 400°C, and to whitish grey at 600°C. The residual compressive strength of spent garnet concrete was also found slightly higher than that for control specimens. At various high temperatures, the reduction in ultimate tensile stress for steel bar inside concrete cover of 30mm was the lowest compared to that of 20 mm.

Research limitations/implications – Spalling effects were not considered.

Practical implications – The optimum concrete cover is important issue in reinforced concrete design. This can be used as a guideline by structural designers when employing a different types of concrete material in the construction.

Social implications – Utilization of the waste spent garnet reduces usage of natural aggregates in concrete production and enhances its performance at elevated temperatures. Natural aggregates are normally
taken from sand and rock. The new innovation in concrete perhaps can produce light concrete, reduce the cost of concrete production and at the same time also mitigate environmental problems effects from waste material such as minimizing disposal area.

"The high-status burial from Planig. An old finding revised." -

Since its excavation in 1939, the early medieval and remarkably rich warrior grave from Planig (Rhine-Hessen, Germany) led to controversial debates – particularly on its absolute chronology. Even now an absolute dating can only be approached: the comparison of Planig to other burials points to the end of the 1st quarter of the 6th century. The research shows parallels not only to burials within the gold hilt spatha horizon but also to those with ring swords. Together with burials from Chaouilley and Krefeld-Gellep the burial from Planig represents a kind of transition horizon. Among the rich burial finds especially the garnet cloisonné attached to the purse mount and the spatha attracts attention. XRF-analyses proved their provenance from the Indian region and have outstanding parallels to recent analyses of Merovingian garnet decoration. Both the ostentatious grave furnishings as well as the burial’s location along a Roman road and near the castellum in Kreuznach emphasise the deceased’s status as belonging to the local elite. Their graves are often located nearby forts or other strategically or economical important places: e.g. the burial from Planig nearby the late Roman fort in Bad Kreuznach, the burials from Flonheim and Eich nearby the fort in Alzey and those from Bretzenheim and Wiesbaden-Biebrich near Mainz-Kastel. All those burials are situated along a Roman road and a nearby fort. The rich burials of early Merovingian age along the Roman Empire’s border at the rivers Rhine and Danube are often located within a late antique fort’s periphery and those in Rhine-Hessia add a Roman road to their preferred location.
Some of the grave goods from Planig are exceptional unique specimen, maybe custom-made items: e.g. the elaborate decorated spatha whose best parallels are from other Rhine-Hessian burials. Both the ango and the franziska are more regional, typical for the Frankish territory. The sax’s filigree as well as the solid gold buckle (“Schilddornschnalle”) are both elements of “newest fashion” and connect Planig to younger burials with ring swords. The solidus was identified as an imitation coin. The chainmail and the riveted plate helmet are both traditional armoury of Byzantine officers.
Some of the objects, e.g. the solidus, maybe came to Rhine-Hessen via trade; while other ones, e.g. the helmet, are individual-related status symbols, which present the elite’s high mobility.
Whether this burial is a so called founder’s grave and where the related settlement is situated remains unknown. Further research to answer those questions and gather more information about Rhine-Hessen’s history would be desirable.

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.

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

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 differential fluid exsolution. (II) late prograde stage (type II and III garnets ± clinopyroxene ± disseminated magnetite): the coexistence of vapour-rich and halite-bearing fluid inclusions in type II garnet and their similar homogenization temperatures (420°–480 °C) presumably signify that fluid immiscibility from a supercritical fluid occurred at lithostatic pressures of 300 to 500 bar, corresponding to a depth of 1.5–2.0 km. (III) early retrograde stage (massive magnetite + pyrite + chalcopyrite + epidote + quartz + type I calcite + amphibole + serpentine + talc): hypersaline liquid and low-salinity vapour phases trapped within the epidote, quartz, and type I calcite are coexisting, indicating phase separation of hydrothermal fluids at temperatures of 300°–400 °C and pressures ranging from 310 to >100 bar under hydrostatic conditions, equivalent to a depth of 1.5 to 2.0 km. Hypersaline inclusions in the quartz and type I calcite show Td(NaCl) > Th(L-V), deduced to have been trapped by the over-saturated fluids or under over-pressured conditions before the hydrofracturing (up to 2200 bars). (IV) Late retrograde stage (type II calcite ± quartz ± chlorite), which is characterized by moderate temperature and salinity and non-boiling fluid inclusion assemblage (with average of 172 °C and 17 wt% NaCl equiv.).

The first boiling event is documented in the type II garnet of the late prograde stage and provoked the ore-bearing fluids to precipitate the disseminated iron ore. The main deposition of magnetite has plausibly been triggered by the second episode of fluid boiling, recorded in epidote, quartz, and type I calcite during the early retrograde stage. Two boiling events mean producing more fractured and brecciated zones, which can act as conduits for the iron-bearing hydrothermal fluids. This seems to be why there are dozens of isolated magnetite orebodies in the Saheb skarn deposit, which extend over an area of greater than two kilometers (in an E-W direction). Comparably higher salinities even in the type II calcite of the late retrograde stage (25 wt% NaCl equiv.) may reveal that significant mixing of saline magmatic fluids with external, dilute, and cold fluids is almost implausible, despite the presence of brecciated zones. Boiling, therefore, can be pondered as the most salient factor in controlling the ore precipitation at the Saheb Fe (Cu) skarn deposit. However, mixing with meteoric fluids and shifting in pH values could also facilitate the alteration and mineralization.

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.

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

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 metaigneous 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.

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.

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.

LOCATION

5S 7E Sec. 13 SBM 33.73394000030 -116.20774000000 (MRDS, 2011)

The reported location of this mine in MRDS is near Indio, California on the northwest side of the Whitewater River

OWNERSHIP

Circa 1961, mine was owned by John I. Fasset, 297 W. 4th Street, San Pedro, CA in 1937 (Saul and others, 1961).

GEOLOGY

The mine is in Quaternary alluvium and conglomerate (Dibblee, 2008b, 2008k). The garnet must be a placer occurrence.

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.

Thermal conductivity at room temperature and pressure (k 0), and heat capacity and total entropy as functions of temperature are calculated for majorite^pyrope garnets from new and previous infrared reflectivity and Raman scattering data. The thermodynamic properties, including the effect of cation disorder, vary by less than 4% over this binary, whereas k 0 changes by s 400% due to cation disorder. For mantle garnet compositions (V70 mol% majorite), k 0 is V2.3 W/m K, which is V25% k 0 of ringwoodite, the other major mineral in Earth's transition zone (TZ). The dynamics of the TZ is governed by its two dominant minerals having disparate values for k and viscosity, which parallels the situation in the lower mantle. If the TZ has substantial (60^70%) proportions of majoritic garnet, as suggested by petrological models, then heat flow therein is inhibited relative to the upper and lower mantles. Subadiabatic temperatures are implied, which is consistent with steep velocity gradients in the TZ. Association of low thermal conductivity with high temperatures should contribute to the buoyancy of the TZ layer, weaken it, and promote transformation to garnet: such destablization through positive feedback possibly provides a mechanism for catastrophic overturns of the TZ and upper mantle.

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

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.

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

Abstract

The aim of this study is to provide data about the morphological characteristics and chemical composition of garnets from the Precambrian metamorphites of the Zhalti Chal Formation in the rim of the Sakar Pluton, Southeast Bulgaria. The garnets which have been studied are from the region of the villages Orlov Dol (along the Sokolitza and Kondus Dere rivers and to the west of Gyoptepe along the road to Madretz), Hlyabovo (along the Golyamata Reka and from the chlorite schists with magnetite) and Dervishka Mogila. The previous name of Golyamata Reka is Yavuz Dere. The predominant form in the garnets from the Precambrian metamorphic rocks in the rim of the Sakar Pluton is rhombododecahedral 110 crystals and combinations of rhombododecahedral 110 crystals with small 211 faces. There are two generations of the garnet – with pre-tectonic and with syntectonic crystallization. The investigated garnets are dominantly with almandine composition and show a variety in the values of the other components. All analysed garnet porphyroblasts express “normal” chemical zoning.
Key words: garnet, morphology, chemical zoning, Sakar

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.

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.

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...