Natrolite is a mineral of the zeolite group and belongs to the silicate class. Chemically, it is a hydrated sodium aluminium silicate. It typically forms colourless to white crystals, often with a slender prismatic or needle-like habit. The crystals may occur individually, in sprays or as dense radiating aggregates.

Like many zeolites, natrolite commonly forms in cavities within volcanic rocks, particularly basalts and other mafic to intermediate volcanic rocks. It usually develops as a secondary mineral from low-temperature hydrothermal fluids. Natrolite is often associated with other zeolite minerals, calcite and additional late-stage cavity minerals.

Well-known natrolite localities occur in many volcanically influenced regions of Europe and other parts of the world. Germany also hosts several classic localities, including the Richter quarry near Hammerunterwiesenthal in the Ore Mountains and the Mahlscheid basalt quarry near Herdorf. At such localities, well-developed white to colourless crystal aggregates may occur.

Interesting natrolite associations are also known from Norway. In the quarries around Sagåsen near Porsgrunn, natrolite occurs together with diaspore and may form pale, contrasting aggregates on matrix.

Natrolite is particularly appreciated by collectors for its delicate crystal forms and its often highly aesthetic radiating or spray-like aggregates. Its generally pale colour can also create a strong contrast with darker volcanic host rocks or coloured associated minerals.

The Mineralien Weltweit range includes natrolite specimens from several localities in Germany and Norway. Each specimen is documented with precise locality information, dimensions, weight and original photographs.