Nephrite pebbles of the Vitim Highlands and the Hetian area (China): a comparative mineralogical and geochemical analysis

Research subject. Placer nephrites of the Vitim Highlands and the Hetian area in northwest China.

Aim. Comparison of mineralogical and geochemical characteristics of nephrite pebbles from the Tsipa River in the north-east of the Republic of Buryatia and the world’s largest accumulation of placer nephrite from the Yurunkash and Karakash Rivers in the Xinjiang Uygur Autonomous Region, Northwest China.

Materials and methods. The mineral composition of placer nephrite from the Vitim Highlands was studied by X-ray diffraction on a PowDix600 powder diffractometer; the diffractograms were interpreted using Almaz software. The chemical composition was studied by SEM (EDX) on a Merlin Carl Zeiss scanning electron microscope equipped with an AZtec X-Max energy dispersion spectrometer (Oxford Instruments). The content of 59 trace elements and rare earth elements was determined by ICP MS method on an iCAP Qc ThermoFisher Scientific inductively coupled plasma mass spectrometer. Statistical processing of the analytical results was carried out using STATISTICA and Excel software programmes.

Results. The main mineral of light-coloured nephrite pebbles is tremolite, which can change into actinolite, accompanied by a significant (10 times) increase in the FeO content with the acquisition of dark green and black colouring of placer nephrite. Petrochemical diagrams Mg/(Mg + Fe²⁺), MgO + FeO–FeO, Al₂O₃– Na₂O + K₂O, SiO₂–CaO + Na₂O + K₂O allowed to obtain distinct differences between the studied objects. All studied nephrite pebbles have common characteristics of rare earth elements (REE) behaviour: negative Eu-anomaly, pronounced right-hand slope, moderate enrichment of light-REEs, practically flat distribution of heavy-REEs.

Conclusions. The genetic similarity of placer nephrite from both nephrite-bearing areas is confirmed by the common distribution of REE in them. The distinctive features of nephrite pebbles of the Vitim Highlands are elevated content of alkalis associated with the participation of acidic intrusions in the formation of the primary source of nephrite, and a developed staining edge acquired under exogenous conditions. Black nephrite of the Karakash River consists predominantly of actinolite, which are formed at elevated levels of ferric oxide. The similarity of alluvial nephrite of the Tsipa, Yurungkash and Karakash rivers testifies to the great prospects of placers in the Vitim region and the need for specialized geological exploration.

1. Adams C.J., Beck R.J., Campbell H.J. (2007) Characterisation and origin of New Zealand nephrite jade using its strontium isotopic signature. Lithos, 97, 307-322.

2. Bortnikov N.S., Volkov A.V., Lalomov A.V., Bochkneva A.A., Ivanova Yu.N., Lalomov D.A. (2024) The role of placer deposits in ensuring the replenishment of the mineral resource base of scarce types of strategic mineral raw materials in Russia at the present stage. Rus. J. Earth Sci., 24(1), ES1012. (In Russ.) https://doi.org/10.2205/2024es000897

3. Boyd W.F., Wight W. (1983) Gemstones of Canada. J. Gemm., 18(6), 544-562.

4. Dictionary of Placer Geology. (1985) (Ed. by N.A. Shilo). Moscow, Nedra Publ., 197 p. (In Russ.)

5. Ignatov P.A., Hen Ch. (2015) Types of nephrite placers in the Kunlun and the adjacent Tarim Depression of China. Izv. Vyssh. Uchebn. Zaved. Geologiya i Razvedka, (3), 26-34. (In Russ.)

6. Jing Y., Liu Y. (2022) Genesis and mineralogical studies of zircons in the Alamas, Yurungkash and Karakash Rivers nephrite deposits, Western Kunlun, Xinjiang, China. Ore Geol. Rev., 149, 105087. https://doi.org/10.1016/j.oregeorev.2022.105087

7. Jutras J.P., Williams B., Williams C., Rossman G.R. (2023) Nephrite Jade from Washington State, USA, including a New Variety Showing Optical Phenomena. J. Gemm., 38(5), 494-511. http://doi.org/10.15506/JoG.2023.38.5.494

8. Kislov E.V. (2024) Kavokta Deposit, Middle Vitim mountain country, Russia: composition and genesis of dolomite type nephrite. Geosci., 14(11), 303. https://doi.org/10.3390/geosciences14110303

9. Kislov E.V., Khudyakova L.I., Nikolaev A.G. (2023б) Waste from processing apodolomitic nephrite and directions for its use. Gornye nauki i tekhnologii, 8(3), 195-206. (In Russ.) https://doi.org/10.17073/2500-0632-2023-01-75

10. Kislov E.V., Popov M.P., Nurmukhametov F.M., Posokhov V.F., Vanteev V.V. (2023) Nyrdvomenshor nephrite deposit, Polar Urals, Russia. Minerals, 13(6), 767. https://doi.org/10.3390/min13060767

11. Kislov E.V., Popov M.P., Nurmukhametov F.M., Posokhov V.F., Vanteev V.V. (2023а) Nephrite of the Nyrdvomenshor deposit, Polar Urals. Lithosphere (Russia), 23(2), 270-291. (In Russ.) https://doi.org/10.24930/1681-9004-2023-23-2-270-291

12. Lalomov A.V., Bochkneva A.A. (2024) Placer deposits of Russia as a source of strategic types of mineral raw materials. Mineralnye resursy Rossii. Ekonomika i upravlenie, 3(188), 5-18. (In Russ.)

13. Liu Y., Deng J., Shi G., Sun X., Yang L. (2011a) Geochemistry and petrogenesis of placer nephrite from Hetian, Xinjiang, Northwest China. Ore Geol. Rev., 41(1), 122-132. https://doi.org/10.1016/j.oregeorev.2011.07.004

14. Liu Y., Deng J., Shi G., Yui T.F., Zhang G., Abuduwayiti M., Yang L., Sun X. (2011b) Geochemistry and petrology of nephrite from Alamas, Xinjiang, NW China. J. Asian Earth Sci., 42(3), 440-451. https://doi.org/10.1016/j.jseaes.2011.05.012

15. Liu Y., Deng J., Shi G.H., Lu T., He H., Ng Y.-N., Shen Ch., Yang L., Wang Q. (2010) Chemical zone of nephrite in Alamas, Xinjiang, China. Res. Geol., 60(3), 249-259. https://doi.org/10.1111/j.1751-3928.2010.00135.x

16. Liu Y., Zhang R., Zhang Zh., Shi G., Zhang Q., Abuduwayiti M., Liu J. (2015) Mineral inclusions and SHRIMP U-Pb dating of zircons from the Alamas nephrite and granodiorite: Implications for the genesis of a magnesian skarn deposit. Lithos, 212-215, 128-144. https://doi.org/10.1016/j.lithos.2014.11.002

17. Liu Y., Zhang R.-Q., Maituohuti A., Wang Ch., Zhang Sh., Shen Ch., Zhang Zh., He M., Zhang Y., Yang X. (2016) SHRIMP U-Pb zircon ages, mineral compositions and geochemistry of placer nephrite in the Yurungkash and Karakash River deposits, West Kunlun, Xinjiang, northwest China: implication for a magnesium skarn. Ore Geol. Rev., 72(1), 699-727. https://doi.org/10.1016/j.ore-georev.2015.08.023

18. McDonough W.F., Sun S.S. (1995) The composition of the Earth. Chem. Geol., 120, 223-253.

19. Mustoe G.E. (2024a) Nephrite Jade and Related Rocks from Western Washington State, USA: A Geologic Overview. Minerals, 14, 1186. https://doi.org/10.3390/min14121186

20. Mustoe G.E. (2024b) Pleistocene Glacial Transport of Nephrite Jade from British Columbia, Canada, to Coastal Washington State, USA. Geosci., 14, 242. https://doi.org/10.3390/geosciences14090242

21. Portnov A.M., Dronova N.D. (2016) Unique nephrite. Priroda, (12), 18-23. (In Russ.)

22. Sotnikova V.F., Sungatullin R.Kh., Kislov E.V. (2025) First mineralogical and geochemical data on placer nephrite of Vitim Highland, Republic of Buryatia. Lithol. Miner. Res., 60(3), 333-345 (translated from Litol. Polez. Iskop., (3), 346-360). https://doi.org/10.1134/S0024490225700038

23. Suturin A.N., Zamaletdinov R.S., Sekerina N.V. (2015) Nephrite deposits. Irkutsk, IGU, 377 p. (In Russ.) Yurgenson G.L. (2001) Gem and ornamental stones of Transbaikal’e. Novosibirsk, Nauka Publ., 390 p. (In Russ.)