Thulium

It is the rarest of the rare earth metals.

Thulium
Properties
Atomic symbol	Tm
Atomic number	69
Classification	Metallic
Atomic mass	168.93421 amu
Other Information
Date of discovery	1879
Name of discoverer	Per Teodor Cleve
Name origin	From Thule, the ancient name of Scandinavia.
Uses	Radioactive thulium is used to power portable x-ray machines, eliminating the need for electrical equipment.
Obtained from	Found chiefly in monazite and bastnasite ores