Monster Spawner

part 1
Monster Spawner-
Spawners can not be obtained at all in survival mode. The proper tool to mine them with is the pickaxe.
Monster Spawners (sometimes called Mob Spawners) are cage-like blocks that were added in Update 0.9.0. They act as in their name; mobs will spawn around it in a certain radius. It contains a spinning image of the mob that spawns out of it, which spins faster until its mob is released and repeats the process. Mob Spawners are mostly found in Dungeons, Strongholds, and Abandoned Mineshafts, accompanied by Chests containing various items and are presumed to challenge the players that try to raid the chests.
Monster spawning
The mob that spawns from monster spawner is indicated by the small version of that mob spinning inside the spawner. However, Stronghold spawners will only spawn silverfish and this spawner is always located in the End portal room. Abandoned mineshaft spawners will only spawn cave spiders.
Nether fortress spawners only spawn blazes. Dungeon spawners can only spawn zombies, skeletons and spiders. There’s a 50% chance a spawner in a dungeon is a zombie spawner and a 25% chance it’s either a spider or skeleton spawner.