References
https://en.wikipedia.org
http://images-of-elements.com/lutetium.php
Lutetium (Lu) is contained in the following rare earth mineral:
Fergusonite
Spessartine
Tortveytit
Area of application: Lutetium isotopes can help reveal the age of ancient items, like meteorites. It also has applications related to petroleum refining and positron emission tomography. Experimentally, lutetium isotopes have been used to target certain types of tumors.