Introduction
Thulium (atomic number 69) is the least abundant of all the naturally occurring rare earth elements (Promethium is excluded as it is synthetic). It is a Heavy Rare Earth Element named after Thule, an ancient name for Scandinavia. Due to its scarcity and high price, it has few common applications.
Chemical & Physical Properties
A silvery-grey metal that is soft, malleable, and ductile. It slowly tarnishes in air and reacts with water.
Occurrence & Production
It is extremely rare, usually found in very low concentrations alongside other heavy rare earths in minerals like xenotime and laterite clays. Its extraction is exceedingly difficult and expensive due to its low abundance and chemical similarity to its neighbors.
Key Applications & Uses
Its applications are limited by its rarity:
- Portable X-ray Machines: Radioactive Thulium-170 (produced by bombarding natural Thulium in a reactor) is used as a radiation source in small, portable X-ray devices for medical or industrial imaging in remote locations.
- Lasers: Used in specific types of solid-state lasers for surgical and meteorological applications.
- Euro Banknotes: Used as an anti-counterfeiting fluorescence marker.
Future Outlook & Significance
Thulium remains a highly specialized material. It is studied for potential uses in magnetic ceramic materials, but its scarcity makes widespread industrial adoption unlikely.