Faujasite

Faujasite is a natural zeolite mineral in the zeolite group, classified as a faujasite (FAU) framework. It is an aluminosilicate with a three-dimensional network of AlO4 and SiO4 tetrahedra linked by oxygen atoms, producing a negatively charged framework balanced by exchangeable cations such as Na+ and Ca2+. The structure contains large cages connected by 12-membered rings, forming spacious pore openings that can accommodate relatively large molecules.

Natural occurrence: Faujasite forms through the secondary alteration of volcanic rocks, particularly basalts and other alkaline igneous rocks, in vesicular cavities. It commonly occurs with other zeolites such as chabazite and natrolite and is sought by mineral collectors as well as for industrial exploration.

Variations: In nature, two varieties are described: Faujasite-X (the sodium-rich form) and Faujasite-Y (the higher-silica form often containing calcium). The same faujasite structure underpins the synthetic zeolites X and Y, widely used in industry as adsorbents and catalysts; sodium faujasite (X) is typically used as an adsorbent or catalyst support, while higher-silica faujasites (Y) are favored in catalytic applications.

Uses: Faujasites are valued for their large pore systems and ion-exchange properties. They are employed as adsorbents for gas separations and water purification, and as catalyst materials or catalyst supports in petrochemical processing, including cracking and hydrocracking, as well as in environmental remediation and detergents.

History: The mineral was named after the French geologist and mineralogist Jean-Baptiste Faujas de Saint-Fond (1741–1819), in honor of his studies of zeolites.