Crystal Shard

Crystal Shards are a common Hardmode crafting material found in the Underground Hallow, where they grow on Pearlstone Blocks and Pink Ice Blocks, even when submerged in Water or Lava. They respawn randomly on Pearlstone and Pink Ice blocks in the Cavern layer and below, making farming possible. Crystal Shards are most easily harvested using a Pickaxe, but can also be freed by mining the blocks surrounding them. They emit a small amount of light, similar to Demonite Ore.

Crystal Shards are also placeable in nearly any position (on walls, floors, and ceilings) as background Furniture, though they are not nearly luminous enough to replace other light sources, and placement has no other functional effect. Although new Crystal Shards will only spawn on Pearlstone blocks in the Cavern layer, once harvested they can be placed anywhere.

Crafting all items, including only one color of Phasesaber, but excluding Crystal Bullets and Greater Healing Potions, requires 135 Crystal Shards. Add 250 to this number for one of each color Phasesaber.

Tips

 * Crystal Shards only appear in the cavern layer, and are an indication of actual Underground Hallow, as opposed to Hallow entities having strayed into other biomes.
 * Crystal Shards have an unusually high sell value relative to their commonness, so farming them can be one of the most effective ways of making money throughout Hardmode. A full stack is worth more than (platinum). Single horizontal rows of Pearlstone, separated by three tile-wide gaps for walking and harvesting, make farming easy. The farm must be in the cavern layer. It may be worth sealing the farm using an outer frame of Clay Blocks or Wood followed by a three-block gap to prevent Hallow from spreading.
 * Crystal Shards emit a glow, so getting rid of light sources makes it much easier to spot them.
 * Crystal shards are usually plentiful but the underground hallow will need time (not a long time) to produce large quantities of them so it's best to do other stuff (like work your way up to full adamantine/titanium armor) and not hunt for them really early on.