Mordenite

Mordenite is a naturally occurring zeolite mineral, a hydrated aluminosilicate with a porous three‑dimensional framework built from tetrahedrally coordinated silicon and aluminum linked by oxygen. The framework carries negative charges that are balanced by extra-framework cations, typically sodium, potassium, and calcium, with water molecules occupying the internal pores.

Natural mordenite forms in hydrothermally altered volcanic rocks such as tuffs and rhyolites and is commonly reported from zeolite facies environments. It occurs as colorless to white or pale yellow crystals, often in prismatic or tabular habits, or as granular masses. It is frequently associated with other zeolites such as analcime, natrolite, and chabazite.

Structure and properties: Mordenite has a relatively high silica-to-alumina ratio, contributing to chemical and hydrothermal stability compared with some other zeolites. Its framework features channels formed by rings of tetrahedrally coordinated atoms, including large pore pathways that enable diffusion of moderately large molecules. This pore structure gives mordenite useful adsorption and shape‑selective properties, making it relevant for certain catalytic and separation processes.

Uses: While natural mordenite is primarily of mineralogical and academic interest, purified or synthetic mordenite is used as a catalyst and adsorbent in petrochemical processing and gas separation. It serves as a catalyst support and as a material for separations that exploit size and shape selectivity. Its stability and ion‑exchange capabilities also contribute to its value in various industrial applications.

Notes: As with other zeolites, heating can drive off water from the pores, and impurities in natural samples can affect behavior. Synthetic variants allow tuning of Si/Al ratio and acidity for targeted applications.