Rare Earths

Rare Earths: a group of 15 chemical elements with atomic numbers from 57 to 71. Rare Earths are commonly divided into three categories:

• Light Rare Earth Elements (LREE): from Lanthanum to Samarium
• Medium Rare Earth Elements (MREE): from Samarium to Holmium
• Heavy Rare Earth Elements (HREE): from Erbium to Lutetium

back to the gemological glossary