Obsidian

Obsidian is a unique pre-Hardmode ore which is created when Water and Lava collide, at which point it forms placed blocks of Obsidian which can be mined and collected. Though Obsidian is considered an ore and is gathered similarly, it has no bar form of its own (although it is used to craft Hellstone Bars). Mining Obsidian requires a pickaxe with at least 65% pickaxe power (Nightmare Pickaxe or it's counterpart Deathbringer Pickaxe are the weakest pickaxes able to mine Obsidian). Explosives can also be used to mine Obsidian.

Tips

 * A good way to rapidly acquire obsidian with little effort is to put in contact a large pocket of water with a large pocket of Lava, by digging a small conduct in the water pocket leading to the bottom of the lava pocket. Then, one can safely collect obsidian in a way lava falling on water will produce an obsidian block at the exact spot of the block that has just been collected.

Trivia

 * Obsidian in real life is cooled volcanic glass. It is a very brittle substance that chips easily.

History
Obsidienne 흑요석 Обсидиан