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Abstract <p>The localization features of jewelry garnet (demantoid) in small Alpine-type ultramafic massifs in the Middle Urals are studied. The chemical composition of demantoid of the Poldnevskoye, Korkodin, and Novy Ufalei deposits is studied in details. It is shown that andradite (98–99% end-member) is azoned. The U–Pb (ID-TIMS) age of the demantoid–topazolite andradite from the Korkodin deposit is 307 ± 13 Ma. Paragenetic mineral assemblages are identified on the basis of mineral composition of host rocks and vein series indicating the crystallization of demantoid during the progressive stage of metamorphism and Ca&#xa0;metasomatosis. The rock bodies consisting of fine-grained andradite with a higher REE content, which are identified for the first time, indicate the impact of decompression fluids on ultramafic rocks at the boundary of ~300 Ma.</p>

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Jewelry Demantoid (Andradite) and Its Host Serpentinites of the Middle Urals Ultramafic Massifs

  • 期刊论文

  • 发表日期：

    2026年5月31日

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  • A. B. Makeyev,
  • E. N. Terekhov,
  • N. B. Kuznetsov,
  • M. V. Stifeeva,
  • E. B. Salnikova,
  • S. E. Borisovsky,
  • L. A. Ivanova,
  • O. I. Okina

摘要

Abstract

The localization features of jewelry garnet (demantoid) in small Alpine-type ultramafic massifs in the Middle Urals are studied. The chemical composition of demantoid of the Poldnevskoye, Korkodin, and Novy Ufalei deposits is studied in details. It is shown that andradite (98–99% end-member) is azoned. The U–Pb (ID-TIMS) age of the demantoid–topazolite andradite from the Korkodin deposit is 307 ± 13 Ma. Paragenetic mineral assemblages are identified on the basis of mineral composition of host rocks and vein series indicating the crystallization of demantoid during the progressive stage of metamorphism and Ca metasomatosis. The rock bodies consisting of fine-grained andradite with a higher REE content, which are identified for the first time, indicate the impact of decompression fluids on ultramafic rocks at the boundary of ~300 Ma.