[3] The name is derived from natron (νατρών), the Greek word for soda, in reference to the sodium content, and lithos (λίθος), meaning stone.

Needle stone or needle-zeolite are other informal names, alluding to the common acicular habit of the crystals, which are often very slender and are aggregated in divergent tufts.

Between crossed nicols the fibers extinguish parallel to their length, and they do not show an optic figure in convergent polarized light.

The mineral is readily fusible, melting in a candle-flame to which it imparts a yellow color owing to the presence of sodium.

Excellent specimens of diverging groups of white prismatic crystals are found in compact basalt at the Puy-deMarman, Puy-de-Dôme, France.

[5] The Bay of Fundy in Nova Scotia, New Jersey, Oregon, and British Columbia have also produced excellent specimens.

Natrolite forms opaque white spherical inclusions within nodules of translucent green prehnite from Wave Hill, Northern Territory, Australia.