Nether Reactor Core

The Nether Reactor Core is a block. It is the main component in constructing the Nether Reactor. It is the only way to obtain Glowstone, Nether Quartz and Melon in-game as of 0.6.0.

Crafting
Crafting the Nether Reactor Core requires three diamonds and six iron ingots.

Bugs
However this is possibly intentional because without the use of inventory editing or hacking, gold blocks can be hard to obtain.
 * If you mine the core while it is still active, it will remain active, but nothing else will spawn after you mine it out; the glowing obsidian will still be there, no holes will appear in the nether spire since the game glitches and thinks the Nether Reactor is still active, and it will remain night time. When you go to sleep, it will turn to day, but will shortly turn back to night after. Exiting the app, then deleting it from your history (iOS devices only) then going back on the game will restore the normal night and day pattern and fix the glitch but the glowing obsidian will still be there. If you mine out the glowing obsidian, the drop is regular obsidian.
 * A burnt-out core can be reactivated by mining it out and then rebuilding the reactor pattern again. If rebuilt in the exact spot as earlier, the Nether Spire will be replaced with another exactly like it, and will spawn Zombie Pigmen (Non-Peaceful only), melon seeds, doors, Glowstone dust, and will repeat the process until 45 seconds have passed. If built away from the location of the original reactor, it will spawn another spire, making it possible to have two Nether Spires in one world.
 * It is possible to save gold blocks after activation. The player can activate the reactor normally, and there is a short period of time where the gold blocks will not turn into obsidian, and that is the the time it is possible to retrieve the gold blocks.