About mssbauerite from the bottom sediments of the freshwater lakes of the Ilmensky reserve (South Urals)

Additional data on fougerite group minerals from the bottom sediments of the Bolshoy Tatkul Lake of the Ilmensky Reserve (South Urals) are given. It is shown that in fougerite-bearing sediments all iron is connected with carbonate component namely with such members of the group as trebeurdenite and mssbauerite. The last forms two various polytypes, mssbauerite-2T and mssbauerite-3T. Polytype 2T has not been noted in nature before.