Heulandite-Na, Opal-A (Var: Opal-AN), Dolomite
Traun river dam, Pucking, Linz-Land District, Upper Austria, Austria
Cross-section of blocky, slightly zoned heulandite-Na crystal (brighter areas contain slightly more Ba and K) grown on a thin, globular hyalite layer covering slightly zoned (Fe) dolomite. Very dark grey = resin.
SEM photo.
This polished section was described in:
Kolitsch, U. (2015): 1935) Almandin, Aragonit, Baryt, Heulandit-Na, ...
© Uwe Kolitsch