Editing Guide:Getting started (section)

=== 26. Locate a lava pool and create {{InvSprite|Obsidian}} obsidian. ===
Obsidian is an import resource that you will want to become familiar with. It is the most durable resource in the game, taking a long time to mine and being immune to explosions. It can only be mined with a diamond pickaxe. While obsidian is a great building block, the main use is for creating portals to the Nether, a hellish alternate dimension filled with strong monsters and lava.

You can create obsidian by having water spill out on top of a lava pool. Use a water bucket to bring some water down to an underground lava pool, then place it on top of the lava. The lava will quickly cool and become obsidian. You can mine it with your diamond pickaxe, but be careful not to accidentally fall into the lava blocks below! You may want to stand at the side of the lava pool and sneak by holding Shift, then begin mining the obsidian while holding W. You will pick up the obsidian block without falling into any lava below you. Make sure to mine fourteen pieces of obsidian for the next step.