The clays and minerals that thulium occur in also contain high amounts of other lanthanides. The mineral monazite is in the ore which is used the most for thulium extraction and isolation. Due to the fact that all the lanthanides have similar chemical characteristics, separating them from the minerals in which they occur in together is very difficult. The complexity of the isolation process, and the rarity of the metal, makes small scale laboratory isolation of thulium nearly impossible.
The isolation process of thulium begins with treating the ore monazite to sulfuric acid, hydrochloric acid, and sodium hydroxide. This mixture extracts the lanthanides, including thulium, out in their salt form. Additional treatments using solvent extractions and ion exchange chromatography further isolate thulium from the other lanthanides. The reduced fluoride from of thulium is then reacted with pure calcium under heated conditions to yield a purer form of thulium metal. Any calcium contaminants that remain are removed through vacuum processes.