Abandoned Adventurer's Satchel

The Abandoned Adventurer's Satchel is found on rare elite mobs in Northrend, and has a 100% chance to drop from them. Most, but not all, of the mobs from which it drops contribute to the achievement.

Source
This item drops from the following rare elite mobs:

Contents
Will contain 20 Frostweave Cloth, a gold amount anywhere around 15-25G and possibly some of the following:
 * Crystallized Life
 * Crystallized Shadow
 * Crystallized Earth
 * Crystallized Water
 * Crystallized Air
 * Crystallized Fire