Rubidium carbonate, Rb2CO3, is a simple to use compound of rubidium; it is stable, it does not react a lot, and dissolves in water.
It is how most rubidium is sold in.[source?]
This can be made by putting ammonium carbonate to rubidium hydroxide.
It is used in some types of glass-making by making glass more stable and durable as well as making electricity flow through it harder. It is also used to prepare chains of short alcohols from feed gas by increasing the rate which it reacts.