Bloodstone blocks are a building block found in the Opulence section of inventory. They are greenish black with red streaks. Each block occupies one square block of space and has full collision.
How to Obtain
You can craft bloodstone blocks, trade for them, or mine them from many naturally-generated hell biome structures.
How to Use
Bloodstone blocks are great for building hellish structures with a dark, gloomy feel. They cannot be further crafted into any other item. Unlike most blocks that can be decayed, a distressed version of this block will return the original bloodstone block back.
Although the ore necessary to craft bloodstone blocks can only be found in hell biomes, the bloodstone block itself, like all bloodstone items, can be placed in any biome type.
In the early months of the game, bloodstone ore was extremely difficult to discern from regular earth in hell biomes. However, mining a decayed bloodstone block would return bloodstone ore into your inventory. Since one bloodstone ore crafts 3 bloodstone blocks, this exploit allowed players to visit a hell world once, and then fill their inventories with bloodstone ore and blocks without ever having to go back. Many early builds using huge amounts of bloodstone came out of this exploit.
Once the developers caught on, bloodstone blocks were changed so that mining decayed items would simply result in original versions of the block going into inventory.