TY JOUR TI Talc shales in the Lower Paleozoic Chuval Formation in the upper reaches of the Uls River (Northern Urals) KW shales KW Chuval Formation KW chemical composition KW talc KW serpentine KW chromite JO Vestnik of geosciences AU Nikulova, N.Y. AU Bogatyrev, L.I. AU Zarkhidze, D.V. AU Shuyskiy, A.S. PY 2026 IS PB FSBI FIC "Komi Scientific Center of the Ural Branch of the Russian Academy of Sciences"