Letters that make rubidium
b, d, m, r, i, u are letters that make 'rubidium'
1 possible definitions for 'rubidium'
Under this definition, rubidium is a noun and has the following properties:
Rb, atomic number 37 have the same meaning as 'rubidium'
'rubidium' can be a type of metallic element, metal.
'rubidium' can be a substance of carnallite, lepidolite, pollucite.