Obsidian

Obsidian is a deep purple block that was first released into the game in version 0.30. Obsidian may be found on rare occasions, when there is flowing Water and still Lava nearby. Obsidian is created when flowing water hits a lava spring; when water and flowing lava collide, cobblestone is created. Obsidian never actually spawns with the chunk, but is created by the environment. Obsidian can only be successfully mined with a diamond pickaxe. Each obsidian block takes 15 seconds to mine when using a diamond pick. It can be mined with a non-diamond pickaxe, but this takes 50 seconds and will not yield a collectable block. Obsidian can be destroyed by TNT although it will need to take a total of 6000 damage points before breaking without dropping anything.



Obsidian in the wild is somewhat rare and difficult to mine since it usually rests on top of a Lava block. Obsidian farming is thus the preferred way to acquire large quantities. A basic Obsidian farm is composed of a trough seven blocks long into which seven blocks of Lava are poured using the Bucket. A water block is then placed on top of one end of the trough so that it flows onto the lava and converts it into Obsidian.

As of the Halloween Update, Obsidian can be used to create portals to The Nether. This requires at least 10 blocks of Obsidian (14 for a full frame) and Flint and Steel.

History
Obsidian was available for use since Classic mode. It is generally used for making dark things, or the black lines of Pixel Art.

In Survival Test mode, Obsidian was extremely tough to break and would drop one or two Cobblestone blocks when busted.

Obsidian was removed in Indev and brought back in Infdev. Obsidian was used to mark the positions of the cardinal directions. This created two intersecting planes extending just above the surface of the solid material that surrounds them. This has since been removed.

Possible Future
Notch has mentioned he may require floating islands to have obsidian in the future:

Later, when asked about making floating blocks fall, he answered:

Trivia
Even though Obsidian is the hardest block to destroy, in reality Obsidian is a sort of glass made by volcanoes and is actually quite fragile. The misconception is probably due to obsidian being able to reach sharpness comparable to - if not greater than - diamond while being easier to produce, and thus being a favored material in Stone Age cultures for usage as blades and arrow tips.

Obsidian