Other common rubidium compounds are the corrosive rubidium hydroxide (Rb OH), the starting material for most rubidium-based chemical processes; rubidium carbonate (Rb Sr.
During fractional crystallization, Sr tends to concentrate in plagioclase, leaving Rb in the liquid phase.
German chemists Robert Bunsen and Gustav Kirchhoff discovered rubidium in 1861 by the newly developed technique, flame spectroscopy.
Rubidium metal is easily vaporized and has a convenient spectral absorption range, making it a frequent target for laser manipulation of atoms.
Rubidium is not a known nutrient for any living organisms.
The resonant element in atomic clocks utilizes the hyperfine structure of rubidium's energy levels, and rubidium is useful for high-precision timing.
It is used as the main component of secondary frequency references (rubidium oscillators) in cell site transmitters and other electronic transmitting, networking, and test equipment.
Both of those deposits are also sources of caesium.
Although rubidium is more abundant in Earth's crust than caesium, the limited applications and the lack of a mineral rich in rubidium limits the production of rubidium compounds to 2 to 4 tonnes per year.
Similar to other alkali metals, rubidium metal reacts violently with water.
As with potassium (which is slightly less reactive) and caesium (which is slightly more reactive), this reaction is usually vigorous enough to ignite the hydrogen gas it produces.
During magma crystallization, rubidium is concentrated together with its heavier analogue caesium in the liquid phase and crystallizes last.