Petrogenesis of Chatoyant Green Nephrite from Serpentinite-Related Deposits, Ospinsk, Russia: Insights from Mineralogy and Geochemistry

He, Weishi; Bai, Feng; Qu, Hongting; Li, Xuemei

doi:10.3390/cryst13020252

Cited by 3 publications

(2 citation statements)

References 47 publications

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“…No carbonate minerals have been observed in previous studies of the S-type nephrite. Minor minerals commonly found in S-type nephrites, such as spinel, chlorite, serpentine, chromite, magnetite [46][47][48], are not found in Xinyu nephrites. According to the above characteristics, we can speculate that Xinyu nephrite is not of S-type genesis.…”

Section: Preliminary Discussion On the Genesis Of Xinyu Nephritementioning

confidence: 95%

A New Nephrite Occurrence in Jiangxi Province, China: Its Characterization and Gemological Significance

Wei,

Shi,

Zhang

et al. 2024

Minerals

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Nephrite is a very precious gemstone material. As a non-renewable resource, the discovery of new nephrite deposits and the study of the genesis of nephrite have aroused great interest. A new occurrence of nephrite known as Xinyu nephrite was discovered in Xinyu Country, Jiangxi province, China. Field investigations reveal that nephrite appears in a contact zone between the Mengshan composite granitic pluton and Permian carbonate rock. The carbonate rock is calcic marble that underwent diopsidization and tremolitization. Nephrites have a light yellow-green color, weak greasy luster, are slightly-translucent to translucent, and are fine-grained. Their refractive index (RI) ranges from 1.60 to 1.61, and their specific gravity (SG) value ranges from 2.90 to 2.91, falling within the range of nephrites from Xinjiang, China. Their Mohs hardness (Hm) ranges from 5.78 to 5.83. Petrographic observations and electron probe micro analyzer (EPMA) data indicated that analyzed nephrites mainly comprise tremolite, with minor diopside, calcite, quartz, and apatite. Tremolite has a ratio of Mg/(Mg + Fe2+) greater than 0.99. The tremolite grains show microscopic fibrous-felted and columnar textures. Scanning electron microscope (SEM) images show some tremolite fibers interwoven in different crystallographic orientations, and some arranged in parallel. Fourier transform infrared and Raman spectroscopy features reveal the bands of minerals typical for nephrite composition. The petrographic characteristics and geological background of the Mengshan area indicate that nephrite formed through a replacement of calcic marble, which differs from the two known types (D-type: dolomite-related; S-type: serpentinite-related). Mineral replacements were common in nephrite, including diopside by tremolite, calcite by tremolite, and recrystallization of coarse by fine tremolite grains. The discovery of Xinyu nephrite occurrence complements the resource and provides an updated case for the in-depth study of the diversity of nephrite deposits.

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Section: Preliminary Discussion On the Genesis Of Xinyu Nephritementioning

confidence: 95%

A New Nephrite Occurrence in Jiangxi Province, China: Its Characterization and Gemological Significance

Wei,

Shi,

Zhang

et al. 2024

Minerals

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“…Tremolite makes up 95%-100%, and there is a fine uniform inclusion of chrome spinel, replaced by magnetite (1%), up to 2 mm in size [20,47]. There is a "cat's eye" effect [48].…”

Section: Discussionmentioning

confidence: 99%

Nyrdvomenshor Nephrite Deposit, Polar Urals, Russia

et al. 2023

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We studied the quality characteristics, chemical, mineral and isotope composition of nephrite, diopsidite and rodingite of the Nyrdvomenshor nephrite deposit in the Polar Urals. We applied visual petrographic and mineralogical studies, X-ray spectral fluorescence, ICP-MS analysis, and a scanning electron microscope with a dispersive microanalysis system, to measure the oxygen isotope composition. According to its quality characteristics, the nephrite was substandard. Here, uvarovite, which forms idiomorphic grains, sometimes sheath-like and less often xenomorphic elongated, and substituting the chromite, was commonly encountered. The nephrite was formed due to both metamorphic and metasomatic processes. The serpentinite was replaced by diopsidite, which was then replaced by nephrite. The metamorphism intensified the metasomatism of the serpentinite melange and provided the cryptocrystalline tangled-fibrous structure of the nephrite. Then, metamorphism and metasomatism led to the formation of omphacite and the cracking of the nephrite, which reduced its quality. As these processes progressed, the contribution of the crustal fluid increased.

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Magmatic (Cr–Ni–PGE) and secondary/hydrothermal (emerald–peridot–rodingite–nephrite jade) mineralization associated with ultramafic–mafic complexes of Pakistan

Jan,

Ullah,

Anjum

2024

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Mafic magmatism has repeatedly taken place in Pakistan throughout its geologic history from the earliest Proterozoic to Recent. Much of it, however, does not have associated metallic mineralization. This paper concerns mineralization associated with mafic-ultramafic plutonic rock occurrences in the western- and northern suture zones of Pakistan, which demarcate the collision boundary between the northwestern Indian plate and Eurasian blocks. We discuss the petrology of the ophiolites and basaltic magma-related chromite deposits, showings of PGE and Ni minerals, and secondary mineral deposits (emerald and peridot gems, rodingite, and nephrite jade) associated with mafic-ultramafic complexes of the two suture zones. Chromite with high Cr#s (68 to 85) occurs in fair quantity and is mostly considered to be genetically related to basaltic magma of subduction-related environments. PGE and nickeliferous minerals are insignificant in quantity; PGE's are formed by a higher degree of partial melting and melt-rock reaction, whereas Ni-sulphides are the product of serpentinization of the ultramafic rocks. Emerald occurs in several localities in the ISZ, whereas the peridot has so far been reported from only one locality. Emerald is associated with Mg-carbonate ± quartz ± fuchsite ± talc ± serpentine, and peridot (Fo 89-92 ) is associated with chrysotile ± magnesite ± talc ± magnetite ± ludwigite. Both are formed via hydrothermal alteration of ultramafic rocks through the introduction of hydrous fluids incorporating CO 2 , Be, B, K, Al, and possibly Na. In view of the undeformed nature of the emerald and peridot and the 23 Ma age of emerald formation, the mineralization appears to post-date deformation and may be of Late Oligocene-Early Miocene age. The metasomatising fluids were either derived from the subducting Indian plate crust underneath the Kohistan arc or were related to 23-26 Ma silicic magmatism in this area of the NW Indian plate. The nephrite jade in the ophiolite mélange is hosted in serpentinites and has disseminated grains of chrome spinel with elevated Fe/(Mg + Fe) ratios (0.10–0.18), implying low-grade metamorphism of ultramafic rocks (protolith of serpentinite) with loss of Al and introduction of SiO 2 during accompanying metasomatism. The rodingite in Dargai ophiolite could have formed by the action of seawater channeled through fractures and cracks in rocks. However, their mineral assemblages indicate that they formed as a result of the influx of Ca, Al, and Na-bearing hydrothermal fluids related to the intrusion of gabbros/sheeted dykes in the serpentinized ultramafic rocks, resulting in Ca-metasomatism.

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Petrogenesis of Chatoyant Green Nephrite from Serpentinite-Related Deposits, Ospinsk, Russia: Insights from Mineralogy and Geochemistry

Cited by 3 publications

References 47 publications

A New Nephrite Occurrence in Jiangxi Province, China: Its Characterization and Gemological Significance

A New Nephrite Occurrence in Jiangxi Province, China: Its Characterization and Gemological Significance

Nyrdvomenshor Nephrite Deposit, Polar Urals, Russia

Magmatic (Cr–Ni–PGE) and secondary/hydrothermal (emerald–peridot–rodingite–nephrite jade) mineralization associated with ultramafic–mafic complexes of Pakistan

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