Pollucite


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pollucite

[pə′lü‚sīt]
(mineralogy)
(Cs,Na)2 Al2Si4O12·H2O A colorless, transparent zoolite mineral composed of hydrous silicate of cesium, sodium, and aluminum, occurring massive or in cubes; used as a gemstone. Also known as pollux.

Pollucite

 

a mineral, a hydrous aluminosilicate of the composition (Cs, Na) [AlSi2O6nH2O. Pollucite contains 26–32 percent Cs2O and admixtures of Rb2O, K2O, and Tl2O. The crystal structure is basically an aluminosilicate framework of bonded SiO4 and AlO4 tetrahedrons; Cs+ and Na+ cations and zeolitic H2O are arranged in the interstices of the framework. Pollucite crystallizes in the isometric system, generally forming dense masses and granular aggregates, as well as pockets, sometimes as large as 1 m in diameter; in hollows it occurs in the form of crystals. It has a hardness of 6.5 on Mohs’ scale and a density of 2,860–2,900 kgm3. Its color is white, occasionally light pink. Often the mineral is colorless and transparent. Physically it resembles quartz.

Pollucite occurs in granitic pegmatites in association with other minerals. It serves as a primary ore of metallic cesium and its salts.

References in periodicals archive ?
Other pegmatites and greisen have yielded beryl up to 15 cm in association with lepidolite, pollucite, amblygonite, spodumene and topaz.
von (1977a) Pollucite from some African and Scandinavian pegmatites.
Mining of the pegmatites in the EBPP is mostly done by garimpeiros (diggers) in search of precious stones (multicolored tourmaline, aquamarine, topaz, brasilianite, kunzite), and subordinately for cassiterite, columbitetantalite, spodumene and pollucite.
only about half complete at best, loose pollucite crystals, too.
Most of these are well known, such as elbaire, beryl, dachiardite, orthoclase, petalite, pollucite and spessartite.
One or more pods or local units in a schorl-bearing pegmatite proved to contain, among other things, lumps of pollucite, also elbaite, petalite and amblygonite, and as rare accessory minerals a few lumps of allemontite with native arsenic.
The type localities for no less than eight of the approximately 49 known zeolites (barrerite, dachiardite, gismondine, merlinoite, montesommaite, phillipsite, pollucite, and willhendersonite) are within its borders.
Also found was a mass of reddish orange pollucite estimated to weigh about 75 kg and containing numerous flawless areas which could cut gemstones of 1 carat and more.
For instance there was a sharp gray-white translucent pollucite 7 cm across, on matrix, from Paprok, Afghanistan; and a gemmy sherry-brown Gilgit, Pakistan topaz fully 12 cm high, on platy albite: an undamaged single aquamarine crystal weighing 9 kg.