Official Minecraft Wiki Entry
Type Solid Block
Physics No
Transparency No
Luminance No
Blast Resistance 6,000
Tool Grid Diamond Pickaxe
Renewable Yes
Stackable Obsidian64
Flammable No
Drops Grid Obsidian Obsidian
Appears in Minecraft
First Appearances Classic 0.26 Survival Test
Infdev (June 17th 2010)
Block Data Information
Decimal Data Value 49
Hexadecimal Data Value 31
Binary Data Value 00110001
Further EE2-related information
EMC 64

Obsidian is created when Water makes contact with a Lava Source. Obsidian can only normally be mined with a Diamond Pickaxe, however, other mods may have Pickaxes also capable of doing so.

Industrial Craft 2

The blast resistance of Obsidian was changed from 6,000 to 60, which means that both Nukes and Nuclear Reactors are capable of destroying Obsidian within their blast radius'.