Pollucite

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. The chemical formula of Pollucite is Cs(Si₂Al)O₆.nH₂O and its molecular weight is  285.03 gm. Pollucite was first discovered on Elba Island in the Livorno Province of Tuscany, Italy. It is a very rare Cesium (Cs) mineral. Pollucite has a specific gravity of 2.68 – 3.03 (g/cm3) and the refractive index of 1.507 – 1.525 Isotropic. 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.

Category:	Zeolite mineral
Chemical Formula:	Cs(Si2Al)O6.nH2O
Molecular Weight:	285.03 gm
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

 

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)

 

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