Thulium was discovered in 1879 by Per Theodor Cleve. Its name derives from the word "Thule" which is the ancient name for Scandinavia.
Thulium's melting point is at 1545.0 C (1818.15 K, 2813.0 F) and its boiling point is at 1727.0 C (2000.15 K, 3140.6 F).
Thulium is a silvery-gray, soft, malleable, and ductile metal and it slowly reacts with air and water (slowly with cold water and quickly with hot water).
Thulium can be cut with a knife.
Thulium has a very high price tag and it is very rare.
Thulium can not be found freely in nature but it is found in minerals with other elements, particularly in mineral monazite and xenotime.
Thulium is the penultimate most abundant element of the lanthanides.
Thulium's only stable isotope is thulium-169 which is the most abundant isotope.
Thulium is mainly produced in China.
Thulium is used in the following applications: lasers used in military and medicine, portable x-ray devices, cancer treatment, industrial radiography, high-temperature superconductors, and part of euro banknotes against counterfeiting.
Thulium has no known biological role and it is not considered toxic.