Minecraft wiki entry for Mining, associated text: This involves digging a quarry and adding ledges every few blocks down around the outside while digging. The sides of the quarry have to be a certain length, for example with a two-space branch mine, the player need each side to be 3n+1 blocks long. The result will vaguely resemble a shopping mall atrium with one massive open space and then a bunch of "shelves". Then, dig the shafts to at least 20 blocks for a ton of ores, including quite a few diamonds (about 3 blobs) down on the lower levels. For a 10×10 quarry, they will get about 150 stacks of cobblestone, while for larger mines (e.g., 40×40), they will get around 2000 stacks, handy for massive building projects.