Purple Default Block

The Purple Default Block is the non-textured, default block that is the base template for textured/existing blocks. It may appear when the texture for a block has been removed or cannot be found, such as for the Locked Chest, or when the player edits the inventory or uses the /give command to spawn blocks with an incorrect data value, such as a wool block at data value 16. For example, when placed, it will appear as white wool, but will appear as such to the player.[clarify]

Properties
This block cannot be placed unless hacked into it by using programs such as MCEdit.