Cobalt Ore

Cobalt Ore is an ore that appears in the world when the player destroys a Demon Altar with a Pwnhammer. This will "bless" the world with deposits of either Cobalt, Mythril, or Adamantite Ore. These ores can then be found randomly throughout the Underground and Cavern layers. Cobalt Ore can only be mined with a Molten Pickaxe or better. It is immune to all types of explosions. It is the most abundant of the three hardmode ores.

Trivia

 * Cobalt is a poisonous, magnetic metal.
 * Cobalt is actually a key part of vitamin B12, which is necessary for living beings. However, Vitamin B12 has extremely low toxicity and is safe to take even in enormous doses.
 * Cobalt is named after the Kobold, at that time thought of as a mischievous spirit.
 * Pure cobalt is an element found on the periodic table just after iron, and is actually silver-like in color, however, cobalt is never found pure in nature.
 * Cobalt's historic primary use was as a pigment used especially in glass or porcelain, as it turns a rich "cobalt blue" when in the compound form of Smaltite, which is made of cobalt, iron, and nickel combined with Arsenic. Historically, along with lapis lazuli, this made cobalt one of the few mineral blue pigments, making it an extremely valuable commodity.
 * The naginata is Japanese and the armor resembles samurai armor so it is likely that cobalt is Japanese themed.