Mesolite is one of the more fragile members of the Zeolite group and forms almost exclusively in delicate, needle-like crystal habits. It is closely related to Natrolite and Scolecite, and can appear very similar to them, though Mesolite’s fiber-like crystals are typically the thinnest crystals of the three minerals. Its color is white, colorless, off-white and light yellow. It is transparent to translucent with a vitreous luster. This unique mineral is associated with other numerous quality and contrasting minerals, including Stilbite, Thomsonite, Heulandite, Calcite and Apophyllite.
The crystal system for Mesolite is monoclinic, commonly forming in acicular and radial groupings, often in cavities and vugs (this particular form is very aesthetic and provides natural protection for the mineral crystals). Other forms include globular masses and hairlike tufts.
A popular mineral with collectors, quality Mesolite specimens are found in limited localities, including Denmark, Iceland, Scotland, India and the USA (Washington).