Combination of Green Diopside and light pink Thomsonite pseudomorph on white calcite.
The Thomsonite is totally undamaged, while the Diopside crystals on the edges are damaged.
You will also see some small and damaged cola-brown Grossular.

The stone is very nice on the part that becomes visible during exhibition.

There is two Diopside crystals that are very loose, with high probability that these will loosen during transport (I will do the best I can to prevent it). One of them is located on the top, and one is located in the middle.

Thomsonite pseudomorph
It is a very rare combination, and my father found just a few ones like this. I have now got it proven by a 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.