The Rare Earth Elements are of the Lanthanide and Actinide series. Most of the elements in the Actinide series are synthetic or man-made.

Brief Facts about the Discovery and History of the Element Protactinium
Protactinium was discovered by Fredrich Soddy in 1917

Occurrence of the element Protactinium
Obtained from fission product of plutonium, uranium & thorium

Common Uses of Protactinium
Basic scientific research

The Properties of the Element Protactinium
Name of Element : Protactinium
Symbol: Pa
Atomic Number: 91
Atomic Mass: 231.03587 amu
Melting Point: 1600.0 °C - 1873.15 °K
Boiling Point: Unknown
Number of Protons/Electrons: 91
Number of Neutrons: 140
Crystal Structure: Orthorhombic
Density @ 293 K: 15.4 g/cm3
Color: silver