Crying Obsidian

Mystery block refers to an abandoned project by Jeb that can only be found in the form of a texture in "terrain.png". This block has been added in Beta 1.3 but is currently not used in the game. This block closely resembles Obsidian, but it's still unknown as what it might be. It also appears to be a Sandstone texture modified to look like Obsidian. There is no indication yet as to whether this block will be implemented in the future.

It is also known as "Bleeding Obsidian" or "Crying Obsidian" among many members.