DRESSERITE

Dresserite is one of those species that is assumed to be widespread, but in reality is known from just one very limited occurrence. Chemically, a barium aluminium carbonate hydroxide hydrate, it was characterized on material found at the famous Francon quarry within Montréal, Québec, Canada during the 1960s. Never colourful, and never especially large, the snow-white 'balls' comprising many radiating acicular crystals sit lining cavities within pale grey carbonatite. The largest spherical spray on this piece reaches about 3 mm in diameter and all of the sprays are in excellent condition. Francon quarry closed in 1981 and so the supply of specimens is fuelled only by the recycling of older collections. From the comprehensive systematic collection assembled by the brothers Martin and Michael Günther (1951-2007 & 1956-2021).