Chabazite

Chabazite from Cairns Bay, Flinders, Victoria, Australia, measuring 91 × 52 × 32 mm and weighing 168 grams. A well-sized specimen of one of the signature zeolites of the Victorian basalts.

Chabazite is a trigonal zeolite whose crystals are rhombohedra so close to cubes that they are often mistaken for them; looking closely at the angles is how you tell the difference. It is also well known for penetration twins, and for the flattened, lens-shaped habit that collectors call phacolite. In chemistry it is variable, with calcium, sodium and potassium all able to dominate, which is why Mindat now separates several Chabazite species by their main cation.

Victoria's Older Volcanics basalts are one of the best Chabazite regions in Australia, and Cairns Bay on the Flinders coast is among the documented localities, where Chabazite occurs alongside Gmelinite-Na, Analcime and other zeolites. The species name comes from an old Greek word used for a stone. With its David Vince Collection provenance, this is a cornerstone piece for anyone collecting Victorian zeolites.