ECONOMIC GEOLOGY AI•D BULLETIN OF THE SOCIETY OF ECONOMIC GEOLOGISTS

A lead isotope study was made on ores and cryptic lead in rocks from southeast Mis-souri to ascertain the source of lead in the major galena deposits of the area. The results indicate that all the lead could have been derived from the sandstone aquifer, Lamotte Sandstone, which underlies the host rock of the ore. The Precambrian basement, the calcitic and dolomitic limestone of the Bonneterre Dolomite (host of the ore) and the calcareous hales of the Davis Formation, which overlies the ore, appear to be eliminated as a major source of lead in the ores. The lead production from the old lead belt could have been gathered from about 11,000 square miles of the Lamotte