Iritonium Coin

Iritonium Coins are a type of money in Terraria. They are not the coin level after Platinum, as they are only dropped by certain enemies as opposed to being created by 100 Platinum, cannot be stored in the coin slot, and are only accepted as money by the Excellent Salesman NPC. However, an Iritonium Coin is worth around 100 Platinum.

Trivia

 * Iritonium means Incredible!, or Excellent! in Nyman, a language invented by HDMaster.
 * This is why the Excellent Salesman accepts them as money.