People often ask how I got mud. This one I got from a , "Hey Joan!" when I crossed the street after a trip to the post office. Chris Griner gave me sediment from a cruise of R/V Tansei Maru that was monitoring radiation in sediment off Japan. He assured me that the mud wasn't “hot”.
He grabbed a bag to scribble on, showing me the location off Japan
Best to learn more by Googling radiation chemist Ken Buesseler. He came to speak with me about commissioning some bowls and he had his Geiger counting gizmo with him -- It attached to his Iphone and we went through my closets of materials testing things--that reassured me.