Corium from Chernobyl.
Corium is the lava-like gunk that results from a nuclear reactor meltdown. It can be made of made of nuclear fuel (i.e. uranium, plutonium), fission products, control rods and anything else that hot mess manages to assimilate such as bits of reactor and concrete floors. Needless to say, it’s pretty hot, in both a thermal and radioactive sense. Apparently it can spontaneously generate dust, which leads me to believe my house must be full of corium. Also, it’s probably worth mentioning I am an artist not a scientist.