Emerald Ore

Emerald Ore is a block that drops Emeralds when mined with an Iron Pickaxe or better; it does not require smelting. It's only been generated in certain biomes, at the moment it's confirmed to be generated below extreme hills and jungle biomes, and not been generated below desert and ocean. The ore seems to spawn anywhere between levels 1 and 30 - it's worth noting that this is similar to the range of gold and lapis.

History
Starting from Survival Test, Diamond was apparently going to be called Emerald.

Emerald Ore was first seen in the preview screenshot from Jeb and had a red texture; it was later released in snapshot 12w21a.

It is unknown wether or not Jeb is going to make emerald equipment (Emerald sword,armor,etc.).

Bugs

 * Jeb forgot to change the color of the ore in snapshot 12w21a, so it appears red rather than green.