Heheh, if you wanna get to the specifics it's not even a metal. That would be cobalt.
Off-topic
Fun Fact:
Did you know that a kobold is a mischievous house elf or a gnome that lives underground, both in German folklore? Methinks Blizzard got the image of kobolds a little wrong, and if they didn't, could you imagine one of those ugly buggers running around your house?! Ugh...