Minecraft wiki entry for Mining, associated text: TNT is expensive to manufacture (requiring 4 sand and 5 gunpowder to make 1 TNT), thus another mining technique to maximize the use of each TNT is to dig a 2×1 tunnel 4-5 blocks into the wall, then at head height mine 2-4 blocks (depending on desired size of hole) to their front, right, left, up and down. Place 1 block of dirt to act as a stand for the TNT to explode in the middle. The explosion should create a roughly spherical shaped hole averaging 8 blocks in diameter. This method destroys more blocks per TNT but requires more use from the pickaxe in order to carve the space around the TNT. Since this only creates a single explosion unlike the previous technique, the items dropped from the broken blocks will survive.