Gonnardite

Gonnardite from Boral Quarry, Bundoora, Melbourne, Victoria, Australia, measuring 66 × 57 × 30 mm and weighing 108 grams.

Gonnardite is a fibrous zeolite closely related to both Natrolite and Thomsonite, and the three can be difficult to distinguish from hand specimen alone since they share a similar fine, radiating crystal habit within basalt gas cavities. Its presence at Bundoora, alongside the better-known Phillipsite and Chabazite from the same quarry, is a reminder of just how many related zeolite species can turn up within a single basalt flow once it's been worked long enough for collectors to document it properly.

This specimen comes from the Allan Waldon Collection. A documented Gonnardite from an Australian locality is a nice, less commonly seen addition for anyone already collecting the more frequently offered Bundoora zeolites.