Obsidian

Obsidian is a type of block found in the update 0.28_01. It is coloured dark purple and blue.

Obsidian is never to be found in a generated map. It was originally thought that obsidian was cooled lava, which could emerge if it collides with water, however stone is actually created.

In Survival mode, Obsidian takes longer to mine than any other material. Unfortunately it only gives you one cobblestone block.

In one version of Indev, obsidian blocks were 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. Now, it appears they have been removed, replacement is unknown.

Obsidian may cause things to float.