pollucite

Pollucite is a rare cesium-containing aluminosilicate mineral that belongs to the feldspathoid group. Its ideal chemical formula is CsAlSi2O6, and the structure consists of a framework of tetrahedral SiO4 and AlO4 units that create cages in which cesium ions reside. The mineral crystallizes in the tetragonal system and typically forms colorless to white crystals, sometimes pale yellow, with a vitreous luster. Crystals are commonly tabular or pseudo-cubic, and the mineral often occurs as coatings or small prisms. Hardness is generally reported around 5–6 on the Mohs scale, and the specific gravity is about 2.9–3.0.

Occurrence and formation: Pollucite forms in granitic pegmatites and other alkaline igneous rocks, where irregular cesium and alkali-element enrichment occurs. It is typically found in association with other cesium- and lithium-bearing minerals such as lepidolite, spodumene, eucryptite, and amblygonite.

Occurrence and sources: Pollucite is rare but has been reported in several Cs-bearing pegmatites worldwide. Notable deposits include the Tanco pegmatite in Manitoba, Canada, among others. The mineral is of particular economic importance because it is the principal ore of cesium.

Uses: As the primary cesium ore, pollucite concentrates are processed to produce cesium compounds used in electronics, specialized catalysts, glass manufacturing, and, most famously, in atomic clocks and other high-precision timing devices.