The Rare Earth Elements: An Introduction Today

Terbium through lutetium, plus yttrium. These are rarer and often more valuable due to their specific high-tech applications.

Lanthanum through gadolinium. These are generally more abundant. The Rare Earth Elements: An Introduction

REEs are the "vitamins" of modern industry—required in small amounts but essential for performance. Terbium through lutetium, plus yttrium