Stilbite shows a wide variation in exchangeable cations: silicon and aluminium ions occupy equivalent sites and can substitute for each other.

Stilbite is usually monoclinic 2/m, meaning that it has one twofold axis of rotational symmetry perpendicular to a mirror plane.

[7] The color is usually colorless or white, also yellow, brown, pink, salmon, orange, red, green, blue or black.

Stilbite is biaxial (-) with refractive indices: Where sources give cell parameters for stilbite-Na, they are the same as those for stilbite-Ca.

[13] The open channels in the stilbite structure act like a molecular sieve, enabling it to separate hydrocarbons in the process of petroleum refining.

[5] Stilbite is abundant in the volcanic rocks of Iceland, Faroe Islands, Isle of Skye, Bay of Fundy, Nova Scotia (where it is the provincial mineral), northern New Jersey and North Carolina.

Salmon-pink crystals occur with pale green apophyllite in the Deccan Traps near Mumbai (Bombay) and Pune, India; white sheaf-like groups encrust the calcite (Iceland-spar) of Berufjord near Djupivogr in Iceland; brown sheafs are found near Paterson, New Jersey in the United States; and crystals of a brick-red color are found at Old Kilpatrick, Scotland.

Excellent white bow ties of stilbite are found here on calcite and quartz, associated with heulandite and laumontite in cavities.

Small, lustrous, white or pink, pointed blades of stilbite-Na, and formless masses, up to 5 cm in diameter, have been found there, covering a thin crust of reddish heulandite in large fractures and cavities in the highly weathered volcanic andesite or rhyolite.