Heulandite is one of the more common Zeolite minerals. It is a very colorful mineral; common colors include beige, pale yellow, brown, pink, white, colorless and gray, while less common colors are green, red, burgundy, orange or black. It is typically transparent to translucent with a vitreous to pearly luster. An interesting habit is its tendency to form inside of volcanic bubbles (vesicles), or more commonly referenced as, cavities. This setting is quite appealing and provides natural protection for the mineral crystals. This colorful mineral is associated with other numerous quality and contrasting minerals, including Stilbite, Apophyllite, Calcite, Quartz, Scolecite, and other Zeolites.

The crystal system for Heulandite is monoclinic, commonly forming elongated tabular crystals, with a wider center,  narrower edges, and flat top and bottom, thus called “coffin shaped” crystals. Other forms include curved crystal aggregates, barrel-shaped, radiating, fan-shaped, chisel-tipped, foliated, in rosettes and in geodes and cavities.

Heulandite is a common mineral. Notable localities for quality specimens include Australia, Iceland, India, Italy, Portugal and the USA (Idaho, New Jersey).