Pollucite

Pollucite is a rare mineral from the mineral class of silicates and Germanates. It crystallizes in the cubic crystal system with the composition ( Cs, Na) 2Al2Si4O12 • H2O and rare forms cubic, dodecahedral or trapezoid- shaped crystals up to 12 cm in size, but usually rounded, solid grains and is colorless, white or gray, sometimes pink, purple or blue.

Pollucite forms with a mineral analcime series.

Etymology and history

Pollucite was first found in 1846 by August Breithaupt in the type locality of San Piero in Campo, on the Italian island of Elba. He named the mineral after the Greek mythical figure of Pollux Pollux at first, later the name was changed to pollucite. The reason for the choice of this name is that the mineral is always associated with Petalite, which he named accordingly Kastor. The mineral was by C. F. Plattner also chemically analyzed, but there was not yet aware of the contained element cesium, he determined the mineral erroneously as strong in potassium.

Classification

In the classification by Strunz mineral to zeolites, a subgroup of the scaffold or tectosilicates is counted. In the 8th edition it forms with analcime, faujasite (Ca), faujasite (Mg), faujasite (Na), paulingite (Ca ), paulingite ( K) and Wairakite a group of Würfelzeolithe. In the 9th edition it forms with Ammonioleucit, analcime, Hsianghualith, leucite, Lithosit and Wairakite a subset of the chain silicates with simply connected four- membered rings.

In the classification by Dana pollucite belongs to the zeolite group of framework silicates, forming with analcime, Hsianghualith, laumontite and Wairakite a group.

Education and Locations

Pollucite is found in lithium - rich granite pegmatites. It is associated with quartz, spodumene, Petalite, Amblygonite, lepidolite, elbaite, cassiterite, columbite, apatite, eucryptite, muscovite, K-feldspar, albite and Microklin.

The major findings of pollucite are known from Lac du Bonnet, Manitoba, Canada. Other important localities are Elba, Bikita in Zimbabwe, Karibib in Namibia, Afghanistan, Pakistan, Skellefteå in Sweden, Itinga in Brazil and the U.S. states of Maine, Connecticut, South Dakota and California.

Crystal structure

Pollucite crystallizes in the cubic crystal system in the space group with the lattice parameters a = 13.67 Å, and 16 formula units per unit cell.

Use

The pollucite ore in Lac du Bonnet are the raw material for the extraction of all cesium compounds and elemental cesium.