Terbium is a chemical element with symbol Tb and atomic number 65. It is a silvery-white, rare earth mGadolinium is a chemical element with symbol Gd and atomic number 64. Gadolinium is a silvery-white, malleable, and ductile rare earth metal.

Atomic Weight:  2323
Density:        54 g/cm3
Melting Point:  56 °C
 Boiling Point: 7676 °C