Location: USA, NEW HAVEN CT

Bricks, pure lead.
931 brick, each with a size 2" x 4" x 8" and weight about 25.75 pound each. They were purchased in about 1963 for a carbon-14 counter experiment. They were selected to be very low in radioactive isotopes, so as provide a low background for the counting. It is my understanding that the materials were derived from old ship ballast, to avoid contamination by radio isotopes, which became more common in the surface environment start in 1950 with the first open-atmosphere testing of nuclear weapons. Chemical analysis will be provided in advance of sale.