Why is cobalt called cobalt?

The word cobalt may date back to theend of the 15th century. In German, the word Kobold means "goblin" or "evil spirt."
The term was used by miners to describe a minereal to describe a mineral that was very difficult to mine and was damaging to their health. When the mineral was heated, it gave off an offensive gas that caused illness.
The gas that affected the miners was arsenic troxide (As4)6), which often occurs with cobalt in nature.