Moonstone

Moonstone is a valuable mineral found on Elpis and used as a form of currency in Borderlands: The Pre-Sequel. It is dropped from slain enemies on occasion as either a single moonstone, or as a moonstone cluster four times the value of a single stone. Badass enemies have a much higher chance of dropping moonstones, and drop clusters fairly often.

Uses

 * Buying character upgrades at the Black Market. These include Bank, Backpack, and Ammunition SDUs.
 * As a recipe enhancement currency used in Grinder recipes.
 * Opening moonstone chests.