POLLUCITE
Class : Silicates
Subclass : Tectosilicates
Crystal system : Cubic
Chemistry : (Cs,Na)(AlSi2)O6 nH2O
Rarity : Uncommon to rare
Although rare, pollucite, belonging to the zeolite group, is the most common cesium mineral. The substitution of cesium by sodium is at the origin of a series with analcime. It is an accessory mineral of sodolithic pegmatites which most often forms veinlets or compact xenomorphic masses of sometimes imposing dimensions (several tonnes). It commonly accompanies microcline, petalite, spodumene, lepidolite, elbaite and beryl. Its name is inspired by the character from Greek mythology Pollux, twin brother of Castor, son of Zeus and Leda because this mineral is commonly found in association with castorite (now known as petalite). Pollucite crystals are rare and frequently corroded. Translucent to transparent, pollucite is colorless to white, bluish or pinkish, with a marked vitrous luster. Massive, it is not easy to distinguish from feldspars. Pollucite is the only cesium mineral that does not suffer from extreme rarity. However, it is too common to constitute a real ore and cesium is mainly extracted from more common minerals where it is present in small quantities, notably feldspars or micas. Some transparent pollucite are cut as fine gemstones.
Main photo : Pollucite from Skardu, Gilgit-Baltistan, Pakistan © Dan Weinrich
Pollucite in the World
Twinning
No twins known for this mineral species.
Fakes and treatments
No fakes listed for this mineral species.
Hardness : 6.5
Density : 2.9
Fracture : Sub-conchoidal
Streak : White
TP : Translucent to transparent
RI : 1.517 to 1.525
Birefringence : 0
Optical character : None
Pleochroism : None
Fluorescence : Sometimes yellow
Solubility : Acids
Magnetism : NoneRadioactivity : None