Pollucite specimen — Photo: Wikimedia Commons · Public domain
Pollucite
A caesium zeolite — the main ore of caesium — from granite pegmatites.
Intro adapted from Wikipedia (CC BY-SA).
Pollucite is an IMA-recognized mineral species in the silicate class, with the chemical formula Cs(Si₂Al)O₆·nH₂O.
It crystallizes in the cubic crystal system (space group Ia3d). It is a member of the Analcime structural group.
Key properties: Mohs hardness 6.5–7; specific gravity 2.68–3.03; Vitreous; greasy to dull on the exterior luster.
IMA symbol Pol, IMA status: approved, named in 1846.
Found in lithium-rich granite pegmatites; may be in kiloton amounts.
It is found associated with Quartz, spodumene, petalite, amblygonite, lepidolite, elbaite, cassiterite, columbite, apatite, eucryptite, muscovite, potassic feldspar, albite, microcline.
The name comes from Pollux, genative Pollucis, of classical mythology, brother of Castor, for its common association with “castorite" (petalite).