Chernobylite
Chernobylite is a solid solution technogenic compound consisting of a crystalline zirconium silicate and an amount of uranium as high as 10%.
It was discovered in the corium that was formed during the nuclear meltdown of Reactor 4 in the Chernobyl disaster.
Chernobylite is highly radioactive due to its substantial uranium content and contamination by fission products.