Caesium in its purest state is a silvery white light metal, which appears golden yellow due to slightest contaminations.

Atomic number55
Atomic weight132.905
Melting point28.5 °C
Boiling point690 °C
Melting heat15.8 kJ/kg
Specific thermal capacity at 20 °C0.22 kJ/(kg·K)
Thermal conductivity18 kJ/(m·K)
Therm. coefficient for linear expansion Coefficient for linear expansion97·10-6/K

As a general rule, reactions involving cesium are rather vigorous, for example, the element ignites upon contact with atmospheric oxygen and is capable of decomposing water. It ought to be preserved under oil. It is not applicable in the field of foundry technology.