Block of Emerald

Blocks of Emerald are mineral blocks that do not appear in normally generated maps anywhere. Although their primary usage will be decoration, they can also be used to store Emeralds. To acquire a single emerald block, one must craft a 3x3 emerald row in a crafting table.

History
On May 28, 2012, Jeb tweeted an image, featuring a room containing Redstone Lamps and Blocks of Emerald.