These Nertschinsk gem mines started in 1723 are are on three peaks of the Adun-Cholon Mountains: Hoppevskaya Gora (Schorl Mountain), Sherlovaya Gora, Soktuj Gora; and further north near the Urulga River. Most locality attributions are suspect as the gem dealers are not interested.
Ref.: Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 332.