Date of Discovery: 1879
Discoverer: Theodor Cleve
Name Origin: From Thule (ancient name of Scandinavia)
Uses: Power for portable x-ray machines
Obtained From: Gadolinite, euxenite, xenotime

 
Atomic Number: 69
Atomic Mass: 168.9342 amu
Melting Point: 1545.0 °C (1818.15 °K, 2813.0 °F)
Boiling Point: 1727.0 °C (2000.15 °K, 3140.6 °F)
Crystal Structure: Hexagonal
Density @ 293 K: 9.321 g/cm3
Color: Silverish

 
Isotope
Tm-168
Tm-169
Tm-170
Tm-171
Tm-172
Half Life
93.1 days
Stable
128.6 days
1.92 years
2.65 days