Amber

Amber is a Gem. Besides Orange Torches, Amber cannot be used to make anything else the other gems can be made into, such as Grappling Hooks or Phaseblades, although it can be placed as a decoration like the other gems.

Unlike other gems, amber cannot be mined, and can only be acquired by feeding silt and slush to an Extractinator.

Trivia

 * Amber's only purpose is to craft Orange Torches which was added upon request of a "really persistent nagging brit." aka James Bennett (ChippyGaming) http://www.youtube.com/chippygaming a Youtuber who makes Terraria videos among other things.