Pollucite in Sweden: Occurrences, crystal chemistry, petrology and subsolidus history

Abstract

Pollucite is known from three highly fractionated peraluminous pegmatites in the Swedish Svecokarelides at Varuträsk, Utö, and Åkerberg. At all three localities, it was penetrated by several generations of feldspar‐, mica‐ and quartz‐bearing veins, replaced by (K, Rb)‐feldspar, and subsequently argillized. The primary homogeneous pollucite has a uniform composition close to Poll₈₀Anal₂₀ with Si/Al from 2.4 to 2.5. The pollucite underwent breakdown into Cs.Al‐ and Na,Si‐en‐riched blebs, crosscut by several generations of Cs,Al‐rich pollucite veinlets (± quartz), locally flanked by diffuse Na,Si‐enrichment. Late‐stage hydrothermal fluids generated (K,Rb)‐feldspar and forced analcimization by cation exchange along fractures and vein surfaces.

Teertstra, D.K., Černy, P., Langhof, J., Smeds, S.‐A. & Grensman, F., 1996: Pollucite in Sweden: occurrences, crystal chemistry, petrology and subsolidus history. GFF, Vol. 118 (Pt. 3, September), pp. 141–149. Stockholm. ISSN 1103–5897.

Keywords:

• Pollucite
• analcime
• cesium
• granitic pegmatites
• Sweden