The paper describes the composition of skarn garnets of the Novonikolaevskoe Cu deposit (South Urals) in comparison with that of garnets of the Gumeshki and Tarutino skarn copper porphyry deposits in the Urals. Three generations of the andradite-grossular group garnets are distinguished at the Novonikolaevskoe deposit, which is typical of skarn deposits. The median TiO2 content of garnet-1 and garnet-2 is 0.37 wt. % reaching 2.38 wt. % in garnet-3. This TiO2 content of garnets and relatively low Fe contents in some garnets from exoskarns (And40–54) possibly indicates a temperature increase during the skarn formation stage of garnets at the Novonikolaevskoe deposit, as well as relatively higher-temperature conditions of formation of garnet at the deposit compared to those from the Tarutino and Gumeshki deposits. Another reason for the low Fe contents in exoskarn garnets may be low fluid redox conditions during the formation of skarns at the Novonikolaevskoe deposit compared to the Tarutino deposit. According to the composition of garnet, the Novonikolaevskoe and Gumeshki deposits can be classified as Au-Fe-Cu skarn deposits, whereas the Tarutino deposit can be ascribed to a Cu-skarn deposit.
Keywords: skarns, garnet, andradite, grossular, skarn copper porphyry deposits, South Urals, Mikheevskoe deposit, Novonikolaevskoe deposit.
Funding. This work is supported by state contract of the Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry RAS (Moscow, Russia).
Acknowledgements. The authors express their gratitude to the management of the ʺMikheevsky GOKʺ (Chelyabinsk region, Russia) for providing the materials for studies, staff of the Laboratory of Local Analytical Methods of the Moscow State University (Moscow, Russia) and staff of the Laboratory of Crystal Mineral Chemistry of the Institute of Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry RAS (Moscow, Russia) for electron microscopic analysis.
Conflict of interest. The authors declare that they have no conflicts of interest.
Author contribution. Khrebtievsky V.V. – concept development, research, visualization (data visualization/display); Plotinskaya O.Yu. – concept development, editing the final version of the manuscript.
For citation: Khrebtievsky V.V., Plotinskaya O.Yu. Skarn garnets of the Novonikolaevskoe copper deposit (South Urals). Mineralogy, 12(1), 44–59. https://doi.org/10.35597/2313-545X-2026-12-1-3.

Received 02.02.2026, revised 03.03.2026 accepted 12.03.2026

Vladimir V. Khrebtievsky – Graduate Student, Moscow State University, Moscow, Russia; st064292@gmail.com
Olga Yu. Plotinskaya – Doct. Sci. (Geol.-Mineral), Leading Researcher, Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry RAS, Moscow, Russia; plotin@igem.ru

1. Ackerson M.R., Tailby N.D., Watson E.B. (2017) XAFS spectroscopic study of Ti coordination in garnet. American Mineralogist, 102, 173–183. https://doi.org/10.2138/am-2017-5633
2. Belgorodsky E.A., Cherkashov S.A., Grabezhev A.I., Shargorodsky B.M. (1991) Porphyry copper Novonikolayevsky ore cluster. Sverdlovsk, UrO AN SSSR, 54 p. (in Russian)
3. Duan X.X., Ju Y.F., Chen B., Wang Z.Q. (2020) Garnet geochemistry of reduced skarn system: implications for fluid evolution and skarn formation of the Zhuxiling W (Mo) deposit, China. Minerals, 10(110), 1024. https://doi.org/10.3390/min10111024
4. Fedorov S.A. (2016) Typomorphic features of magnetite ores of the Gumeshki copper skarn deposit. XVII Uralskaya molodezhnaya nauchnaya shkola po geofizike (XVII Urals Youth Scientific School on Geophysics). Yekaterinburg, Institut geofiziki UrO RAN, p. 182–184. (in Russian)
5. Fei X., Zhang Z., Cheng Z., Santosh M. (2019) Factors controlling the crystal morphology and chemistry of garnet in skarn deposits: A case study from the Cuihongshan polymetallic deposit, Lesser Xing’an Range, NE China. American Mineralogist, 104(10), 1455–1468. https://doi.org/10.2138/am-2019-6968
6. Girfanov M.M., Sergeeva N.E., Shishakov V.B. (1991) Ore-metasomatic zoning of the Mikheevskoe porphyry copper deposit in the South Urals. Vestnik Moskovskogo universiteta. Seriya 4: Geologiya (Bulletin of the Moscow State University. Series 4: Geology), 5, 75–79. (in Russian)
7. Gorbunov A.A., Alikin O.V., Zakharova A.A., Guseva T.A., Rudashevsky V.N., Gemel V.A. (2019) Peculiarities of ore mineralogy of the Mikheevskoe deposit and Novonikolaevskoe and Zapadny areas (South Urals). Uralskaya mineralogicheskaya shkola-2019 (Urals Mineralogical School-2019). Yekaterinburg, UGGU, 41–44. (in Russian)
8. Grabezhev A.I., Ronkin Yu.L. (2011) U-Pb age of zircons from ore-bearing granitoids of porphyry copper deposits of the South Urals. Litosfera (Lithosphere), 11(3), 104–116. (in Russian)
9. Grabezhev A.I., Gmyra V.G., Vigorova V.G., Palgueva G.V. (2005) Garnets from skarns of the Gumeshki and Tarutino skarn porphyry copper deposits. Vestnik Uralskogo otdeleniya Rossiyskogo mineralogicheskogo obshchestva (Bulletin of the Urals Branch of the Russian Mineralogical Society), 4, 55–60. (in Russian)
10. Gritsenko Yu.D. (2018) Collection of Ti garnets from the Fersman Mineralogical Museum of the Russian Academy of Sciences. Novye dannye o mineralakh (New Data on Minerals), 52(1), 3–5. (in Russian)
11. Jiang X., Chen X., Zheng Y., Gao S., Zhang Z., Zhang Y., Zhang S. (2020) Decoding the oxygen fugacity of ore-forming fluids from garnet chemistry, the Longgen skarn Pb-Zn deposit, Tibet. Ore Geology Reviews, 126(5146). https://doi.org/10.1016/j.oregeorev.2020.103770
12. Koryakina A.V. (2024) Mineralogical and geochemical features of the Tarutino copper skarn deposit (South Urals). Master degree thesis. Moscow, MGU, 144 p. (in Russian)
13. Koryakina A.V., Plotinskaya O.Yu. (2022) Features of mineral composition of skarn rocks at the Tarutino copper deposit (South Urals). Uralskaya mineralogicheskaya shkola -2022 (Urals Mineralogical School-2022. Yekaterinburg, IGG UrO RAN, 88−90. (in Russian)
14. Koryakina A.V., Groznova E.O., Plotinskaya O.Yu. (2022) Features of mineral composition and formation conditions of the Tarutino copper deposit (South Urals): first data. Metallogeniya drevnikh i sovremennykh okeanov-2022. Ot veshchestvennogo sostava k modelyam i prognozirovaniyu mestorozhdeny (Metallogeny of Ancient and Modern oceans-2022. From Composition to Models and Forecast of Deposits). Miass, YuU FNTs MiG UrO RAN, 66–69. (in Russian)
15. Meinert L.D. (1992) Skarns and skarn deposits. Geoscience Canada, 19, 145–162.
16. Ogorodova L.P., Gritsenko Yu.D., Vigasi na M.F., Rusakov V.S., Melchakova L.V., Bychkov A.Yu., Ksenofontov D.A. (2022) Physicochemical study of titanium-bearing garnets. Geochemistry International, 67 (4), 363–378. https://doi.org/10.1134/S0016702922030053
17. Plotinskaya O.Yu. (2023) Porphyry-epithermal systems of the Urals: mineral sources, evolution and zoning. (Doctor dissertation). Moscow, IGEM RAN, 312 p. (in Russian)
18. Plotinskaya O.Yu., Kovalchuk E.V. (2022) Fahlores of Cu-(Mo) porphyry deposits of the Urals. Mineralogiya (Mineralogy), 8(3), 5–22. https://doi.org/10.35597/2313-545X-2022-8-3-1(in Russian)
19. Plotinskaya O.Yu., Azovskova O.B., Abramov S.S., Groznova E.O., Novoselov K.A., Seltmann R., Spratt J. (2018) Precious metals assemblages at the Mikheevskoe porphyry copper deposit (South Urals, Russia) as proxies of epithermal overprinting. Ore Geology Reviews, 94, 239–260. https://doi.org/10.1016/j.oregeorev.2018.01.025
20. Plotinskaya O.Yu., Grabezhev A.I., Zeltmann R. (2015) Rhenium in ores of the Mikheevskoe porphyry Cu–Mo deposit, South Urals. Geology of Ore Deposits, 57(2), 118–132. https://doi.org/10.1134/S1075701515020051
21. Podlessky K.V. (1979) Skarns and metasomatites of iron deposits of the Urals and Caucasus. Moscow, Nauka, 204 p. (in Russian)
22. Puchkov V.N. (2017) General features relating to the occurrence of mineral deposits in the Urals: What, where, when and why. Ore Geology Reviews, 85, 4–29. https://doi:10.1016/j.oregeorev.2016.01.005
23. Rybalka A.V., Kashubina T.V., Petrov G.A., Kashubin S.N. (2007) Central Urals transect: new data on the deep structure of the Urals. Modeli zemnoy kory i verkhney mantii po rezultatam glubinnogo seysmoprofilirovaniya (Models of the Earth’s Crust and Upper Mantle Based on Results of
24. Deep Seismic Profiling). St. Petersburg, VSEGEI, 186–191. (in Russian)
25. Shargorodsky B.M., Novikov I.M. et al. (2005) Unpublished report on evaluation works at the Mikheevskoe porphyry copper deposit. Chelyabinsk, ZAO Mikheevsky GOK, 1160 p. (in Russian)
26. Shargorodsky B.M., Novikov I.M., Aksyonov S.A. (2005) Mikheevskoe porphyry copper deposit in the South Urals. Otechestvennaya geologiya (National Geology), 2, 57–61. (in Russian)
27. Stativko V.S., Skublov S.G., Smolensky V.V., Kuznetsov A.B. (2023) Rare and rare-earth elements in garnets from silicate-carbonate rocks of the Kusa-Kopansky complex (South Urals). Litosfera (Lithosphere), 23(2), 225–246. https://doi.org/10.24930/1681-9004-2023-23-2-225-246 (in Russian)
28. Tevelev A.V., Kosheleva I.A., Burshtein E.F. et al. (2018) State Geological Map of the Russian Federation. Scale 1 : 200 000. Second edition. South Urals Series. Sheet N-41-XXV (Kartaly). Explanatory Note. Moscow, Moskovsky filial VSEGEI, 175 p. (in Russian)
29. Tian Z.D., Leng C.B., Zhang X.C., Zafar T., Zhang L.J., Hong W., Lai C.K. (2019) Chemical composition, genesis and exploration implication of garnet from the Hongshan Cu-Mo skarn deposit, SW China. Ore Geology Reviews, 112, 103016. https://doi.org/10.1016/j.oregeorev.2019.103016
30. Zharikov V.A. (1968) Skarn deposits. Genesis of endogenic ore deposits. Moscow, Nedra, 220–302. (in Russian)
31. Zharikov V.A., Rusinov V.L., Marakushev A.A., Zaraisky G.P., Omelyanenko B.I. (1998) Metasomatism and metasomatic rocks. Moscow, Nauchniy mir, 489 p. (in Russian)