chabaziet

Chabazite is a natural zeolite mineral belonging to the tectosilicate group. Its ideal chemical composition is commonly written as (Ca, Na2, K2)Al2Si4O12·6H2O, reflecting a framework of aluminum and silicon tetrahedra with calcium, sodium, and potassium cations and water molecules occupying the pores in the structure. The mineral is part of the zeolite family, meaning it has a porous, hydrated framework that can host exchangeable cations.

Chabazite typically forms well-developed crystals or fibrous to granular masses in vesicular cavities of volcanic rocks such as phonolites, basalts, and rhyolites. It is commonly found alongside other zeolites, including natrolite, analcime, and stilbite. Color varies from colorless and white to pale yellow, orange, or pink depending on impurities. Crystal habit is often rhombohedral or pseudo-cubic, and the mineral can occur as encrusted aggregates.

Physically, chabazite has a Mohs hardness around 4 and a specific gravity near 2.0–2.2. It exhibits a vitreous luster and is transparent to translucent. In terms of structure, chabazite belongs to the CHA framework type of zeolites, featuring relatively large cages connected by eight-membered rings that permit diffusion of small molecules and enable ion exchange.

Occurrence and significance: chabazite is worldwide in volcanic rock settings and is valued both by collectors and scientists. As a natural zeolite, it can act as a molecular sieve and undergo ion exchange, though its industrial use is typically surpassed by synthetic zeolites. It also serves as a geologic indicator of hydrothermal alteration in certain rocks.