Silex

Silex is an item that allows players to add up to 5 extra levels of  to Pickaxes or Drills through an anvil (1 per use). Legacy version of this item (crafted with 9 Nether Quartz and have the texture Enchanted Quartz) can only be obtained through Players Trading and Auction House. This item will be added along with the upcoming 0.12 Crystal Hollows Update.

Trivia

 * In French, "Silex" directly translates to "Flint", the texture of Silex.
 * This item was originally 'released' for a day accidentally, alongside the Flamebreaker Armor.