Skip to content
Material World
Mineral · (Cs,Na)2Al2Si4O12·2H2O

Pollucite

A caesium aluminosilicate — essentially the only ore of caesium, and therefore of the atom that defines the second.

Ore

Pollucite is a zeolite with caesium in the place sodium would ordinarily occupy, and it is the only mineral that concentrates caesium enough to be worth mining. Economic deposits are correspondingly rare — a small number of pegmatites supply most of the world.

The element's most consequential use needs almost none of it. The second is defined by the frequency of a transition in caesium-133, so every atomic clock that keeps international time depends on this mineral, in quantities a single deposit could supply indefinitely. The volume use is quite different: caesium formate brine is a dense, non-corrosive drilling fluid for high-pressure wells.

Medium confidence Weak evidence checked recently · only one source, so there is nothing to cross-check it against · stated directly by the source

How this connects

Where a connection has been confirmed by an outside reference, that reference is named beside it.

is an ore of

  • Caesium — element · essentially the only commercial source Wikidata

is used as

  • Timekeeping — application · the caesium-133 that defines the second comes from this mineral and essentially nowhere else

is a component of

  • Pegmatite — rock · an accessory of rare-element pegmatites rather than a defining constituent — caesium's only real host, and among the rarest of pegmatite minerals

contains

  • Aluminium — element Wikidata
  • Caesium — element · substitutes within a solid solution — an individual specimen may hold little of it Wikidata
  • Hydrogen — element Wikidata
  • Sodium — element · substitutes within a solid solution — an individual specimen may hold little of it
  • Oxygen — element Wikidata
  • Silicon — element Wikidata

Sources

  • Material World
    Our own writing
  • Wikidata
    Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)

Questions this page answers

Where it comes from, and what it becomes

Follow Pollucite back to what it starts as, and forward into what it becomes. Each step is a documented one — a real route material takes, not a chain of inference.

Downstream — what it becomes

  • Pollucite → is an ore of (essentially the only commercial source) → Caesium → is used as (as a photocathode, exploiting the lowest ionisation energy of any stable element) → Electrical conduction
  • Pollucite → is used as (the caesium-133 that defines the second comes from this mineral and essentially nowhere else) → Timekeeping
  • Pollucite → is a component of (an accessory of rare-element pegmatites rather than a defining constituent — caesium's only real host, and among the rarest of pegmatite minerals) → Pegmatite
  • Pollucite → is an ore of (essentially the only commercial source) → Caesium → is used as (the second has been defined by a caesium-133 transition since 1967) → Timekeeping