Scandium or Sc (21)
Yttrium or Y (39)
Lanthanum or La (57)
Cerium or Ce (58)
Praseodymium or Pr (59)
Neodymium or Nd (60)
Promethium or Pm (61)
Samarium or Sm (62)
Europium or Eu (63)
Gadolinium or Gd (64)
Terbium or Tb (65)
Dysprosium or Dy (66)
Holmium or Ho (67)
Erbium or Er (68)
Thulium or Tm (69)
Ytterbium or Yb (70)
Lutetium or Lu (71)

Televisions
Fluorescent lamps
Superconductors 
Pulsed lasers
Surgical supplies
Camera lenses
Optical glasses
Telescope lenses
Pacemakers
Automotive exhaust systems
Magnets
Electrodes
Aircraft engines
Nuclear control rods
Headphones
X-rays
Computer disks