Heart of the Mountain

The Arkenstone is a hardmode accessory that will appear as a block in the cavern layer once hardmode is triggered. It can be mined and collected with a pickaxe over 190%. The amount of arkenstones that appear in a world depends on world size.
 * Small: 10 Arkenstones
 * Medium: 20 Arkenstones
 * Large: 30 Arkenstones

Stats
The Arkenstone gives 20% health and mana regeneration along with 20% damage and 20% damage reduction.