Block of Emerald

Blocks of Emerald (also known as Emerald Blocks) are blocks for storing Emeralds that do not appear in normally generated maps anywhere. Although their primary usage will be decoration, they can also be used to store Emeralds. .

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