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Pollucite
Current inventory:  0 gems
 

Chemistry:  (Cs,Na)₂(Al₂Si₄)O₁₂ • H₂O  
[Hydrated Cesium Sodium Aluminum Silicate]

Discovered in 1846;   IMA status: Valid (pre-IMA; Grandfathered).
Pollucite is named after Pollux. Pollux and Castor were heavenly twins and brothers of Helen of Troy from Greek mythology. Castor is also the basis for the name "castorite" which is the mineral name for the gem Petalite.

Classification

Mineral Classification:

Silicates

Strunz 8th Ed. ID:

8/J.27-20

8 : Silicates
J : Tectosilicates (network) without anions unfamiliar to the tetraheders
27 : Zeolite group, Analcime - Paulingite series

Crystal Data

Crystallography:

Isometric - Hexoctahedral

Crystal Habit:

Crystals are rare; cubes, dodecahedra, or trapezohedra, commonly striated, up to 12 cm; as rounded grains, fine-grained, massive.

Twinning:

None

Physical Properties

Cleavage:

None

Fracture:

Uneven to Conchoidal

Tenacity:

Brittle

Hardness (Mohs):

6.5 - 7.0

Density:

2.68 - 3.03 (g/cm³)

Luminescence:

Fluorescent; SW UV = cream white, blue green, LW UV = weak orange

Radioactivity:

Barely Detectable, GRapi = 484.85 (Gamma Ray American Petroleum Institute Units)

Optical Properties

Color:

Colorless, White, Gray, Pale Pink, Violet, Blue

Transparency:

Transparent to Translucent

Luster:

Vitreous to Dull

Refractive Index:

1.507 - 1.525  Isotropic

Birefringence:

0.00  Isotropic

Dispersion:

0.012

Pleochroism:

None

Occurances

Geological Setting:

In lithium-rich granite pegmatites; may be in kiloton amounts.

Type Locality:

La Speranza (Pisani's Quarry), San Piero in Campo, Campo nell'Elba, Elba Island, Livorno Province, Tuscany, Italy

Year Discovered:

1846

View mineral photos:

Pollucite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Pollucite is a member of the Zeolite Group of minerals that includes over 40 minerals and these gem-type minerals: Analcime, Barrerite, Chabazite, Epistilbite, Gmelinite-Na, Goosecreekite, Mordenite, Natrolite, Pollucite, Scolecite, Stellerite, Stilbite, Thomsonite and Yugawaralite. Pollucite was first discovered on Elba Island in the Livorno Province of Tuscany, Italy. It is a very rare Cesium (Cs) mineral. It is one of only three gems that have Cesium as an esential part of their chemistry - the other two are Pezzottaite and Rhodizite. Gem grade crystals are rare and small so gems are usually small. Pollucite has very low dispersion, but is a great collector's gem because of its rarity. Current sources of Pollucite are Nilaw, Nuristan district, Laghman Province, Afghanistan; Mogok, Myanmar (Burma); Shengus, Skardu, and Gilgit districts, Pakistan; Transbaikalia, Eastern-Siberian Region, Russia.
 

  
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