Minecraft wiki entry for Cobblestone_farming, associated text: Adding pistons can let a generator extrude a whole line of blocks, safely away from the lava and easily mined as a batch. Subtle variations of these designs can produce "plain" stone as described below. The pistons and other arrangements for these generators can also be repurposed for a basalt generator. Basalt generators don't need the water streams at all, just the lava, blue ice, and soul soil. Note: soul soil is needed, not soul sand. You can convert soul sand to soul soil by making and breaking soul campfires.