Amber is a new material provided by Thaumcraft. It can be used in various magical craftings, or formed into decorative blocks.
It is mined from "Amber Bearing Stone", an ore which appears in single blocks throughout the world. The ore appears equally in all biomes, but more often at shallow depths. It often appears exposed at the surface, even in mountainsides well above sea level. Mining the ore normally drops one piece of Amber per ore block, but Fortune can increase this. (Smelting the ore is also possible, and always gives a single piece.)
Amber chunks can be crafted 4:1 into Amber Blocks. These in turn can either be uncrafted back into 4 Amber, or crafted 4:4 into Amber Bricks. The bricks cannot be uncrafted.