Minecraft wiki entry for Piston_uses, associated text: Players tend to use glowstone for lighting, however, lava is another viable method. A lava light uses an opaque block to hold the source block of lava from the area it flows into (generally a glass tube). Since lava can flow, it can be a space-efficient light source. However, lava takes a long time to dissipate. If you need to flip a switch for immediate darkness, flowing lava lamps are not recommended. However, you may want to consider using a redstone lamp, as it tends to be more resource friendly.