Netherrack

Netherrack (formerly known as Netherstone ) is the most abundant solid block in The Nether. When lit on fire, it burns indefinitely.

Obtaining
Netherrack can only be collected with a pickaxe.

Natural generation
Netherrack makes up most of the Nether's terrain.

Usage
Netherrack can be used as part of a trapping mechanism for Mob farming. It can also be used to protect buildings or places from mobs, mob damage, or other players.

Trivia

 * Netherrack can be destroyed by hand in 2 seconds, making it the stone which can be destroyed in the least amount of time.
 * Netherrack can be mined in 50 milliseconds with a golden pickaxe (or a diamond pickaxe enchanted with any level of efficiency). However, there is a .25 second delay between mining blocks.
 * In the game code, it is referenced as "hellrock".