Rare light pink Thomsonite pseudomorph after Nepheline, combined with cola-brown Grossular on white Calcite.

It is a very rare combination, and my father found just a few ones like this. I have now got it proven by lab that it is in fact Thomsonite. You can also see the mineral listed at Seiland at Mindat: https://www.mindat.org/loc-341193.html

In mineralogy, a pseudomorph is a mineral or mineral compound that appears in an atypical form (crystal system), resulting from a substitution process in which the appearance and dimensions remain constant, but the original mineral is replaced by another.


This specimen is a huge crystallized Thomsonite.
The Thomsonite is "knocked off" on the sides and back, plus a flake of the crystal gone in the front.

In addition you can see brown Grossular that are partly weathered.