Natrolite

Natrolite from Cape Grim, Tasmania, Australia, measuring 50 × 45 × 26 mm and weighing 46 grams. The specimen has a particularly useful collecting record: it was collected by Shane Dohnt in the early 1980s. That documented period gives a personal and historical setting to a compact example of this zeolite mineral.

Natrolite is a hydrated sodium aluminium silicate in the zeolite family. Zeolites are often associated with the later alteration of volcanic rocks, when circulating fluids deposit new minerals within available openings. This general process is an engaging contrast with the original crystallisation of the volcanic rock itself, and helps explain why zeolite localities offer such varied subjects for mineral collectors.

The cream-white needles form a dense radiating fan, with fine lines spreading toward a rounded outer edge. That organised growth is the central pleasure of the piece: many slender crystals combine into a form that can be understood at a glance. An angled light makes the separate fibres and the depth of the spray easier to follow. Shane Dohnt's name and the early-1980s collecting period deserve to remain with this piece. They preserve a link to the person who recovered it and the time when it entered the collecting world. That sort of information gives a natural specimen an additional story, making this Natrolite a connection with Tasmanian field collecting as well as a mineralogical example. The accompanying record describes the collecting location as now defunct, adding significance to the retained collector and era information.