Zeolites are a group of minerals which readily exchange
ions in their crystal structure. Classic locations for zeolites
and associated minerals are the trap rock in New Jersey
and western India. I was fortunate to be in India and acquire
some specimens.

Heulandite with chalcedony

In this specimen, the heulandite is coated with a darker, unknown mineral. It is usually white.

Stilbite and Apophyllite

Stilbite is the salmon clusters, apophyllite is the tetragonal crystals.