Rubidium

A by-product alkali metal for specialty glass, atomic clocks and quantum research, now supplied almost entirely from old stockpiles.

Tech & minor metals · No. 52

• US critical 2025

In 2025 no mine anywhere produced rubidium, so the atomic clocks and fibre glass that need it run on old stockpiles.

Chart: Illustration: Rubidium

Where it comes from

Chart: Map of where it comes from

Rubidium sits in zoned pegmatites, mostly in lepidolite (up to 3.5% oxide) and pollucite. It has always been a by-product, first of cesium mining and then of lithium.

Three things to know

1. The US Naval Observatory's timescale relies on a network of clocks that includes six rubidium fountain clocks.
2. A Western Australian pilot test reported 97% rubidium recovery from ore holding about 7,900 t of rubidium oxide.
3. A 100-gram ampoule cost $2,453 in 2025, so bulk buyers pay far less per gram than the $138 charged for a single gram.

The journey

1. 1 PegmatiteZoned granite pegmatites
2. 2 Host mineralsLepidolite up to 3.5% Rb2O
3. 3 By-productConcentrate from cesium or lithium mining
4. 4 RefiningCarbonate, chloride and other salts
5. 5 End usesSpecialty glass, atomic clocks, research

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