HELIUM IN LIMESTONE AND MARBLE

The helium and uranium content of a number of specimens of marble, Iceland spar, and fossil shell of known age were determined. The sedimentary calcite specimens contained only a small fraction of the helium expected, indicating that most of the uranium is external to the lattice. The marbles, in contrast, conthined much more helium than was calculated from the age and the alpha activity. The helium and uranium content of a number of specimens of marble, Iceland spar, and fossil shell of known age were determined. The sedimentary calcite specitnens contained only a small fraction of the helium expected, indicating that most of the uranium is external to the lattice. The marbles, in contrast, contained much more helium than was calculated from the age and the alpha activity. This appears related to the gaseous inclusions in these materials. (auth)