Chabazite

Chabazite from Cairns Bay, Flinders, Victoria, Australia, measuring 76 × 45 × 32 mm and weighing 80 grams. A smaller, lighter specimen and an easy one to place in a display alongside other Flinders material.

Chabazite belongs to the same structural group as Gmelinite, built from layers of linked six-membered rings of silica and alumina tetrahedra, and the two minerals sometimes grow together at Flinders. This structural link is why some Flinders specimens show Gmelinite overgrown by Chabazite or vice versa. Like all zeolites, Chabazite has an open framework with channels holding water and loosely held cations, which is the property that makes synthetic and natural zeolites so useful in industry as filters and molecular sieves.

Cairns Bay sits on the Flinders coastline, where wave-cut exposures of Eocene basalt reveal the cavities that host these minerals. Mindat records Chabazite there with Gmelinite-Na, Analcime, Cowlesite and other species, documented in Bill Birch's 1988 study. Several Cairns Bay pieces from the David Vince Collection are in this sale, including another Chabazite and two Gmelinite-Na, which gives a welcome chance to compare the two related species from the same bay.