Answer: thoric

AnswerCrossword Clue
thoricgrayish-white, lustrous, somewhat ductile and malleable, radioactive metallic element present in monazite: used as a source of nuclear energy, as a coating on sun-lamp and vacuum-tube filament coatings, and in alloys. Symbol: Th; at. wt.: 23
thoricpertaining to thorium (a metallic element)