A Heart Crystal is a red heart-shaped stone that can be found underground, in the Underworld, Underground Jungle. As of 1.2.3, it can no longer be found in Dungeons. When used in a similar manner to mana crystals, it will permanently increase the players health by 20, to a maximum of 400 health (can be taken to 500 health by obtaining Life Fruit, which are also found in the Underground Jungle). A Heart Crystal is only harvestable with a Pickaxe, Drill or Drax. When broken, a Heart Crystal will drop one Life Crystal.
Heart Crystals cannot be obtained by breaking the blocks under them, and the two blocks it is on cannot be broken until the heart is gone.
The number of Heart Crystals in a world depends on the size of the world: there will be about 200-300 in small worlds, 300-350 in medium worlds, and 400-450 in large worlds.
In a medium world, there are enough Heart Crystals to give 20 players full HP (400 HP).
When lava flows over one of these tiles, it will break and drop a Life Crystal. In the PC version you can hit it with a pickaxe and it will drop but only in xbox will it drop if you hit it with a hammer