A precious ore

Introduction

We signed a treaty with the Borzem clan to get odiemel ore, but since the start of the latest conflict, not a single delivery has been made. Sheros is in constant need of odiemel, so if you ever get close to the Sacred Mine, do think of us, please. Don't worry, I know how to be grateful.

Cunclusion

This is perfect. Here's your reward: this key unlocks an old library in northeast Giant Plains. Ratkins give us these pearls from time to time, in exchange for alcohol and food. Maybe they have some value for you?