I went to my friends’ house to make sure they were safe for anything bad. The house had a low baseline of less than 15CPM. I found a few plates with something in them.
Standard 5min quick background test of middle of house: 12.2 CPM
Yellow plate made of glass containing something radioactive, perhaps uranium, though that is my speculation. The readings for 5 minutes were 291/5 = 58.2 CPM Low. Possible alpha source. The effect died at 4 inches maximum, and was reduced by half by a sheet of paper.