Lodestone

A lodestone is a block that can be used to alter the point where compasses lead.

Breaking
Lodestone requires a pickaxe to be mined, in which case it drops itself. If mined without a pickaxe, then the mining is slower and it drops nothing.

Info
Lodestones cannot be pushed by pistons; however, they can be destroyed by the ender dragon.

Lodestone Compass
a compass on a lodestone causes the compass to point to the lodestone. In addition, the compass uses the enchant and potion glint. If a lodestone is broken, then the compass starts spinning to left and right, similarly to compasses in the End or the Nether. This works in all dimensions. A compass spins if it is set to a lodestone in a different dimension from the one that the player is in. If a lodestone is destroyed while a paired compass is in a chest, shulker box, barrel, furnace, blast furnace, smoker, item frame, armor stand, or any other storage item, the compass does not register that the lodestone is destroyed until the item is retrieved. However, placing a lodestone back in the exact position that the original lodestone was while the compass is still in its container prevents the compass from spinning and unpairing once retrieved from its storage. A lodestone compass allows you to mark the point of a lodestone, meaning you won't get lost in the Nether or the End.

Trivia

 * In reality, the lodestone is a naturally magnetized piece of the mineral magnetite, which can attract iron.

Magnétite Leitstein Magnetita Magnetyt 磁石 Магнетит