From Wikipedia:
“The word cobalt is derived from the German kobalt, from kobold meaning “goblin”, a term used for the ore of cobalt by miners, who thought it worthless and who found that it was poisonous and that it polluted and degraded other mined elements, mainly due to the arsenic and sulfur also found in the ore.”
And:
“Some nuclear weapon designs could intentionally increase the amount of 60Co dispersed as nuclear fallout – this is sometimes called a dirty bomb or cobalt bomb, once predicted by a leading scientist as being capable of wiping out all life on earth.”
I can remember when a “cobalt bomb” was seen as the ultimate “doomsday machine” — and was also misunderstood by folks as being some sort of Bigger (vs Dirtier) Boom.
Oh, the joys of the cold war …