Summary: The top 2 inches of the Lower Magnesian Limestone is feebly but persistently mineralized along its outcrop from Nottingham to Doncaster, predominantly with galena and a little cerussite, frequently with uraniferous asphaltite containing 0·2 to 1% U₃O₈. Wulfenite, both platy and pyramidal in habit, occurs at Bulwell and Kirkby in Ashfield. The mode of formation and the age of these minerals are discussed.