What is Mordenite?
Mordenite is both visually soft and structurally open. Radiating sprays show how a zeolite can fill a volcanic cavity while its channels record the movement and exchange of water and ions.
Mineralogy and crystal structure
Reference formula: (Ca,Na2,K2)Al2Si10O24·7H2O. Mordenite is an orthorhombic zeolite with a channelled framework and variable exchangeable cations and water. Natural crystals are often fibrous or radiating, and the selected COD model represents a natural composition rather than every possible hydration state. Mordenite is classified with silicates and has a orthorhombic crystal system. Typical hardness is 3.5–4.5 on the Mohs scale and specific gravity is approximately 2.1–2.2.
Colour, lustre and habit
Typical colours include white, colourless, pink, cream. The usual fibrous, radiating, prismatic habit and vitreous, pearly lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Mordenite forms in or is associated with volcanic tuffs, basalt cavities, low-temperature hydrothermal veins and altered ash deposits. Important documented localities include Japan, Iceland, India, the United States, Italy and New Zealand.
A white zeolite with a channelled framework
Mordenite is both visually soft and structurally open. Radiating sprays show how a zeolite can fill a volcanic cavity while its channels record the movement and exchange of water and ions.
Collecting and care
Protect fine fibres from abrasion and dust; avoid harsh cleaning and retain the host-rock context.
