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Barton Mine at Gore Mountain, New York State, USA, where garnet has been mined since 1878. Deep red garnet crystals are suspended in black amphibolite. Crystals nearly 1 meter in diameter have been reported here. Coauthor Caddick for scale.
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... Web of Science citation metrics, since the fi rst commercial development of garnet quarries at Gore Mountain in New York State in 1878 (FIG. 2), the primary industrial application of natural garnet has been as an abrasive. Uses have included abrasive powders, water-jet cutting, abrasive blasting (garnet replaced quartz in the late 1980s as a sandblasting medium due to health concerns over airborne crystalline silica), and garnet sandpaper (Olson 2006). Finally, garnet has been a popular gemstone for thousands of years due to its many colors, its hardness, its commonality, and its luster (Galoisy ...
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... Kimyasal bileşimlere göre, granatlar altı uç üye ile temsil edilen iki alt gruba ayrılır. Piralspit alt grubu pirop (Mg3Al2Si3O12), almandin ve (Fe3Al2Si3O12) spessartin (Mn3Al2Si3O12) uç üyelerinden oluşurken, Ugrandit alt grubu grossular (Ca3Al2Si3O12), andradit ve (Ca3Fe2Si3O12) uvarovit (Ca3Cr2Si3O12) uç üyelerinden oluşmaktadır [1], [4]- [8]. Ancak doğada saf uç üyeler çok nadir olarak bulunur. ...
Ancient period naturalist Plinius referred that almandine composition Lal Stones (Granat) which had been widely used in the Hellenistic and Roman periods, were extracted from Alabanda (Çine) and Orthosia (Yenipazar) in Karia in Anatolia. The garnet samples, which are the subject of this study, are found in the middle-high grade, gneiss, and mica-schist in the Menderes Massif in Hacıaliler (Çine-Aydın) region. Purplish-brown and matt garnet porphyroblasts, varying between 0.5-2 cm in size, have crystallized in dodecahedron form. Garnet minerals, display poikloblastic texture in microscopic examinations, are in a highly fractured structure and contain plenty of quartz, muscovite, and opaque mineral inclusions. In line with a non-destructive analysis technique, Confocal Raman Spectroscopy studies, it has been determined that garnets present a total of 10 different Raman vibrations, 910-912, 349 and 553-555 cm-1 strong, and are typically in almandine composition. According to the results of mineral chemistry, garnets have the chemical formula of Alm0.72-0.87 Grs0.07-0.19 Pyr0.02-0.13 Sps0.00-0.02. In accordance with garnet - biotite geothermometer calculations, it was determined that garnets are formed at an average temperature of 565.3 ± 20.8°C and under the pressure of 6.6 kbar. It was concluded that Hacıaliler garnets demonstrated depletion in terms of LIL elements (Cs, Rb, Ba, K, Sr, Pb) in the average continental crust (MCC) multi-element variation diagram. It was discovered that garnet samples demonstrated enrichment in terms of REE (∑REE: 192.2-212.1), (La/Sm)N ratio 2.62-2.89, (Sm/Yb)N ratio 0.31-0.38 and (Eu) /Eu*)N ratio vary between 0.41-0.44 in REE multi-element variation diagram normalized to chondrite. According to the non-destructive gemological tests, the specific gravity of garnet crystals varies between 3.33 and 3.64, and the refractive index values were found to be around 1.80-1.81. According to the L*a*b* color system, the color average of garnet crystals was determined to be as L*: 46.25 a*: 6.55 b*: 6.60 (purplish brown). As a result of mineralogical, geochemical, and gemological evaluations, it has been concluded that Hacıaliler garnet samples have undergone multi-stage metamorphism and have lost their bright and transparent crystal forms through the subsequent geological processes (weathering, alteration, etc.); therefore, they do not present the characteristics of gemstones. In addition, it is thought that garnet samples may have an important potential in terms of their REE contents.
Keywords: Garnet, Gemstone, ICP-MS Confocal Raman Spectroscopy, Hacıaliler Çine
... Garnet, a widely occurring skarn mineral, possesses distinctive zonal structures and chemical properties that enable it to serve as a record and indicator of continuous geological processes and the kinetic mechanisms within associated fluid environments (Smith et al., 2004;Gaspar et al., 2008;Baxter et al., 2013;Qian et al., 2013;Wood et al., 2013;Xu et al., 2013;Xu et al., 2016;Jollands et al., 2018;Jiang et al., 2020). Its growth morphology and geochemical composition are influenced not only by internal factors, such as self-organized growth and the original fluid composition (Gaspar et al., 2008;Park et al., 2019), but also by external factors, including the water/rock ratio, physicochemical conditions, and the pulsed introduction of trace element-enriched fluids (Peng et al., 2015;Zhang et al., 2017;Hyppolito et al., 2019;Shu et al., 2023). ...
... In the metamorphic assemblage, garnet has been shown to be useful in exposing a rich history of metamorphic evolutions in pressure (P), temperature (T) and time (t; e.g. Baxter et al., 2013) dimensions. ...
The thermal histories of Himalayan leucogranites provide critical information for unraveling the post‐collisional geodynamics of the Himalayas. The Ramba Dome is located at the intersection of the Tethyan Himalayan leucogranite belt with the Yadong‐Gulu Rift, and hosts several generations of granitic intrusions. Of these intrusions, the 8 Ma two‐mica granites and garnet leucogranite dykes are the youngest of Himalayan leucogranites. In this study, we focus on the carbonaceous staurolite schist located ~1.3 km from the intrusion to constrain the thermal history of the aureole that marked the cessation of leucogranite magmatism. The schist contains euhedral garnet and staurolite porphyroblasts in a foliated matrix of muscovite + biotite + chlorite + plagioclase + quartz + graphite. The staurolite shows minor compositional variations from the inclusion‐free core to the inclusion‐rich rim. By contrast, the garnet features a distinctive bell‐shaped Mn profile, and increasing Mg# from the garnet core to rims. In a graphite‐bearing equilibrium phase diagram for a modified bulk composition with garnet cores removed, the garnet rim composition suggests a peak temperature of ~550 °C, consistent with an independent thermometer based on the Raman spectra of carbonaceous materials (RSCM; 548 ± 9 °C). The P–T condition lies within the narrow low‐variance field bracketed by the staurolite‐in and chlorite‐out boundaries, indicating minimal overstepping of staurolite nucleation and growth. On the other hand, the garnet core composition indicates 520 °C at 2.5 kbar, about 40 °C higher than the predicted garnet‐in boundary (~480 °C). This apparent temperature overstep corresponds to a small chemical affinity (<5 kJ/mol 12 O) for garnet nucleation, comparable to previous estimates. The sharp boundaries of the high‐Ca sector zoning in the core indicate limited diffusion modification (~1.5 Myr if at the peak temperature). The short thermal pulse involves advective heat transfer by leucogranite emplacement, followed by rapid cooling toward the end of Himalayan magmatism and rapid exhumation likely facilitated by the Yadong‐Gulu Rift.
... Successful geothermobarometry and retrieval of accurate P-T-t-X fluids paths relies on the assumption that mineral assemblages were formed at equilibrium. Equilibrium chemical and isotopic compositions can be modified by subsequent processes such as intra-crystalline diffusion or recrystallization, which can lead to erroneous inferred peak metamorphic P-T conditions (Eiler et al. 1993;Valley 2001;Chakraborty 2008;Ague and Carlson 2013;Baxter et al. 2013;Caddick and Kohn 2013). ...
Knowledge of oxygen diffusion in garnet is crucial for a correct interpretation of oxygen isotope signatures in natural samples. A series of experiments was undertaken to determine the diffusivity of oxygen in garnet, which remains poorly constrained. The first suite included high-pressure (HP), nominally dry experiments performed in piston-cylinder apparatus at: (1) T = 1050–1600 °C and P = 1.5 GPa and (2) T = 1500 °C and P = 2.5 GPa using yttrium aluminum garnet (YAG; Y3Al5O12) cubes. Second, HP H2O-saturated experiments were conducted at T = 900 °C and P = 1.0–1.5 GPa, wherein YAG crystals were packed into a YAG + Corundum powder, along with 18O-enriched H2O. Third, 1 atm experiments with YAG cubes were performed in a gas-mixing furnace at T = 1500–1600 °C under Ar flux. Finally, an experiment at T = 900 °C and P = 1.0 GPa was done using a pyrope cube embedded into pyrope powder and 18O-enriched H2O. Experiments using grossular were not successful.
Profiles of 18O/(18O+16O) in the experimental charges were analyzed with three different secondary ion mass spectrometers (SIMS): sensitive high-resolution ion microprobe (SHRIMP II and SI), CAMECA IMS-1280, and NanoSIMS. Considering only the measured length of 18O diffusion profiles, similar results were obtained for YAG and pyrope annealed at 900 °C, suggesting limited effects of chemical composition on oxygen diffusivity. However, in both garnet types, several profiles deviate from the error function geometry, suggesting that the behavior of O in garnet cannot be fully described as simple concentration-independent diffusion, certainly in YAG and likely in natural pyrope as well. The experimental results are better described by invoking O diffusion via two distinct pathways with an inter-site reaction allowing O to move between these pathways. Modeling this process yields two diffusion coefficients (D values) for O, one of which is approximately two orders of magnitude higher than the other. Taken together, Arrhenius relationships are:logDm2s-1=-7.2(±1.3)+(-321(±32)kJmol-12.303RT)
for the slow pathway, andlogDm2s-1=-5.4(±0.7)+(-321(±20)kJmol-12.303RT)
for the fast pathway. We interpret the two pathways as representing diffusion following vacancy and inter-stitial mechanisms, respectively. Regardless, our new data suggest that the slow mechanism is prevalent in garnet with natural compositions, and thus is likely to control the retentivity of oxygen isotopic signatures in natural samples.
The diffusivity of oxygen is similar to Fe-Mn diffusivity in garnet at 1000–1100 °C and Ca diffusivity at 850 °C. However, the activation energy for O diffusion is larger, leading to lower diffusivities at P-T conditions characterizing crustal metamorphism. Therefore, original O isotopic signatures can be retained in garnets showing major element zoning partially re-equilibrated by diffusion, with the uncertainty caveat of extrapolating the experimental data to lower temperature conditions.
... Garnet, a common mineral in igneous and metamorphic rocks, can show distinct oscillatory chemical zonation (Li et al., 2000;Lackey et al., 2012;Baxter et al., 2013;Wood et al., 2013). Microanalytical techniques such as electron probe microanalyzer (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) allow highresolution analysis of the different zones and unravel the continuous fluid evolution history at the mineral scale. ...
Dongguashan is one of the largest Cu-Au deposits in eastern China, with ubiquitous garnet in the stratiform and skarn orebodies. The stratiform ore-formation remains enigmatic. In this study, we describe the diverse textures and present new U-Pb age and chemical data for the Dongguashan garnet. Garnet in the skarn orebody can be divided into three generations (Grt-1, Grt-2, and Grt-3). Grt-1 and Grt-2 show three zones from core to inner rim to outer rim (a-b-c). Garnet in the stratiform orebody is homogeneous (Grt-s). All garnet types have low MnO, a wide range of Y/Ho ratios, and visible fluid inclusions, indicating that they formed from hydrothermal replacement. Grt-1a, Grt-1b, Grt-2a, Grt-2c, and Grt-3 are oscillatory-zoned, low-Sn, and HREE-rich grandite, which may have formed from reduced HREE-rich fluids. Meanwhile, Grt-1c and Grt-2b are high-Sn, LREE-rich andradite, and may have formed from oxidized LREE-rich fluids. Grt-s is pure, low-Sn, LREE-rich andradite, and that may have formed from oxidized LREE-rich fluids. The Eu behaviors are sensitive to the fluid physicochemical conditions and Cl content. Grt-1, Grt-2, and Grt-s have positive Eu anomalies, and may have formed from acidic and Cl-rich fluids. Grt-3 has negative Eu anomalies and was possibly formed from neutral and Cl-poor fluids. All garnet types at Dongguashan may have formed by infiltration metasomatism in an open system with multiple metasomatic pulses. Grt-1, Grt-2, and Grt-s yielded nearly the same in-situ U-Pb ages of 135.9 ± 2.1 Ma, 135.6 ± 2.2 Ma, and 134.6 ± 1.4 Ma, respectively. We propose that both ore types at Dongguashan deposit are closely related to the Early Cretaceous plutonism.
... a Overview of a type I vein separated from the host rock by two pinkish garnet layers; b type I veins in the field crosscutting the Wo-Grt-Di-bearing marbles; c type II veins; these kinds of veins are significantly thinner than type I veins; d Decimetric garnet porphyroblast crosscutted by a thin, whitish type II vein size with those from this paper, have been reported from micaschist of the Passos Nappe, Southern Brasilia Orogen, Brazil (Hartung et al. 2020). Some authors have explained the occurrence of mega-porphyroblasts in greenschist to granulite facies terrains linked to the structural control by shear zones that could have favored the percolation of fluids leading to megacrystal formation (Cussler 2009;Baxter et al. 2013). ...
The wollastonite-garnet-diopside-bearing marbles cropping out in the Migmatite Complex west to the Tamarispa and San Lorenzo villages share a common metamorphic and deformational history with the surrounding migmatite, with metamor-phic peak conditions between 650 and 850 °C. Within the marble, there is an interesting and rare garnet mineralization. The peculiar characteristic and geological-cultural and touristic attraction of this geosite is the presence of large garnet crystals (up to 20 cm). The whitish rock matrix is characterized by coarse-grained rock-forming minerals (mainly wollastonite, cal-cite, diopside and subordinately pectolite, quartz, plagioclase, epidote, apatite, titanite) with a compositional layering and a weak foliation (S2 schistosity), parallel to that of the surrounding gneiss and migmatites. At the outcrop scale, the giant garnet crystals often show a brown core in high relief surrounded by a darker rim with less relief. Under conservation state, the wollastonite-garnet-diopside-bearing marbles show an evident differential alteration with dissolution processes of the matrix and an increasingly pronounced enucleation of the garnet crystals. The Tamarispa outcrop with spectacular giant garnet crystals is here proposed as a new, potential geosite relevant for didactic, cultural, and touristic purposes. Conservation and valorization aspects are discussed within the more general framework of the geological, natural, and environmental resources of the local territory.
... These specimens also display another crucial fea-ture: the presence of silicate melt preserved as crystallized and glass-bearing inclusions of primary nature. Garnet is one of the most common and widely stable peritectic phases in metamorphic crustal rocks (Baxter et al., 2013), and it has been proven to be able to trap and preserve the melt resulting from crustal melting in more than 40 localities worldwide (Nicoli and Ferrero, 2021;. Although melt inclusions (MI) are being increasingly recognized as a common feature of high-grade terranes (Bartoli and Cesare, 2020), the Gore Mountain inclusions are unique because they contain trondhjemitic melt in a mafic source rock, a feature never reported in previous studies on MI in metamorphic rocks. ...
The garnet megacrysts of Gore Mountain (Adirondacks, US) are world-renown crystals due to their size, up to 1 m in historical record, which makes them the largest known garnets on the planet. We show here that they are also host to the first primary inclusions of trondhjemitic melt found in natural mafic rocks. The petrological and experimental investigation of the inclusions, coupled with phase equilibrium modelling, shows that this melt is the result of H2O-fluxed partial melting at T>900 °C of a lower crustal gabbro. The compositional similarity between the trondhjemitic melt inclusions and tonalitic–trondhjemitic–granodioritic (TTGs) melts makes these inclusions a direct natural evidence that melting of mafic rocks generates TTG-like melts, and provides us with the possibility to clarify processes responsible for the formation of the early continental crust. These TTG embryos represent the trondhjemitic end-member of the melts whose emplacement at upper crustal levels, after being modified by mixing and crystallization-related processes, leads to the formation of the TTG terranes. Moreover, our study shows how the melt from H2O-fluxed melting of mafic lower crust has mismatched major and trace element signatures, previously interpreted as evidence of melting at very different pressures. This poses serious limitations to the established use of some chemical features to identify the geodynamic settings (e.g. subduction versus thickened crust) responsible for TTGs generation and the growth of early crust.
... The grossular proportion was higher in the CW7:3 series than in the W7:3 series, indicating the role of CaCO 3(Figure 3b). Similar to garnet, coesite only appeared in the 7:3 experiment series with a higher proportion of sediments in the starting material.Garnet and coesite are typical mineral phases in Si-rich melting system(Baxter, Caddick, & Ague, 2013). Based on the comparison between the 7:3 and 5:5 series, we suggest that the participation of a high proportion of sediment can increase the stability of garnet and coesite.Because of the low content of Al 2 O 3 in KLB-1, the elevated stability of garnet in the 7:3 experiment series could have resulted from the addition of Al 2 O 3 by sediments. ...
Volcanic arcs usually produce silica-rich magmas that may modify the peridotitic sub-arc mantle, but direct observations on the lithology and geochemistry of the sub-arc lithospheric mantle are rare. An Andean-type arc system is inferred on the continental margin of southeastern China during the Mesozoic time; however, direct petrologic evidence for such an ancient arc is lacking. In this study, we have analyzed whole-rock major and trace elements, Sr–Nd–Pb–Hf isotope, and high-precision olivine geochemistry of the basaltic rocks of the Leizhou Peninsula and Hainan Island, on the South China continental margin. Unlike Hainan Island with only typical ocean island basalt (OIB)-type basalts, the Leizhou Peninsula has volcanic rocks ranging from typical OIB-type basalts to island arc basalt (IAB)-type with enrichment in large-ion lithophile elements and depletion in high-field-strength elements. The IAB-like rocks of the Leizhou Peninsula have less radiogenic Nd and Hf isotopes than the Hainan OIB-type basalts and the sub-continental lithospheric mantle. The IAB-like rocks can be explained by interaction of the Hainan plume with a subduction-derived component based on the plots of Nb/Nb* vs. Ce/Pb, Ba/Nb, Pb/Pb⁎, and SiO2. Olivine phenocrysts with anomalously high Ni and low Ca and Mn contents are consistent with a pyroxenite-rich mantle source for the IAB-like rocks. We suggest that the pyroxenite-rich mantle component of the IAB-like rocks formed by metasomatic reaction between silica-rich arc melts and the sub-continental lithospheric mantle during an ancient plate subduction event. We suggest that these arc-like volcanic rocks record melting of lithospheric mantle pyroxenite triggered by the Hainan plume. Our results are consistent with an Andean-type active continental margin related to subduction of the paleo-Pacific Plate beneath the southeastern China during the Mesozoic.
... The continental crust is the third most important carbon reservoir on Earth (6.5 Â 10 7 GT C), after the core (4 Â 10 9 GT C) and the mantle (3 Â 10 8 GT C) (DePaolo, 2015). Garnet was proposed to represent 4.9 vol% of the total crustal mass (Ronov and Yaroshevsky, 1969), and it is known to form mostly in the T range > 400°C to > 1000°C in metamorphosed crustal rocks (Baxter et al., 2013). As melt is stable from T > 700°C, we considered that~50% of the garnet forms in suprasolidus conditions (i.e. ...
The global geological volatile cycle (H, C, N) plays an important role in the long term self-regulation of the Earth system. However, the complex interaction between its deep, solid Earth component (i.e. crust and mantle), Earth’s fluid envelope (i.e. atmosphere and hydrosphere) and plate tectonic processes is a subject of ongoing debate. In this study we want to draw attention to how the presence of primary melt (MI) and fluid (FI) inclusion in high grade metamorphic mineral could help constrain the crustal component of the volatile cycle. To that end, we review the distribution of MI and FI throughout Earth’s history, from ca. 3.0 Gyrs ago to the present day. We argue that the lower crust might constitute an important, long-term, volatile storage unit, capable to influence the composition of the surface envelops through the mean of weathering, crustal thickening, partial melting and crustal assimilation during volcanic activity. Combined with thermodynamic modelling, our compilation indicates that periods of well-established plate tectonics regimes at < 0.85 Gyrs and 1.7–2.1 Gyrs, might be more prone to the reworking of supracrustal lithologies and the storage of volatiles in the lower crust. Such hypothesis has implication beyond the scope of metamorphic petrology as it potentially links geodynamic mechanisms to habitable surface conditions. MI and FI in metamorphic crustal rocks then represent an invaluable archive to assess and quantify the co-joint evolution of plate tectonics and Earth’s external processes.
... The chemical and physical characteristics of garnet allow it to record a variety of tectonic, metamorphic, and mantle processes, making these minerals very useful for unraveling the petrogenesis of various rock types. The composition of garnet and coexisting mineral phases can be used to decipher the metamorphic conditions and the tectonic environments in which they were formed (e.g., Spear 1993;Baxter et al. 2013). ...
Euhedral andradite crystals were found in trachyandesitic (latitic) lavas of the volcanic Andahua Group (AG) in the Central Andes. The AG comprises around 150 volcanic centers, most of wich are monogenetic. The studied andradite is complexly zoned (enriched in Ca and Al in its core and mantle, and in Fe in this compositionally homogenous rim). The core-mantle regions contain inclusions of anhydrite, halite, S- and Cl-bearing silicate glass, quartz, anorthite, wollastonite magnetite and clinopyroxene. The chemical compositions of the garnet and its inclusions suggest their contact metamorphic to pyrometamorphic origin. The observed zoning pattern and changes in the type and abundance of inclusions are indicative of an abrupt change in temperature and subsequent devolatilization of sulfates and halides during the garnet growth. This process is interpreted to have taken place entirely within a captured xenolith of evaporite-bearing wall rock in the host trachyandesitic magma. The devolitilization of sediments, especially sulfur-bearing phases, may have resulted in occasional but voluminous emissions of gases and may be regarded as a potential hazard associated with the AG volcanism.
