Genthelvite with Aegirine

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The remarkable Mont Saint-Hilaire geological complex at La Vallée-du-Richelieu RCM, Montérégie, Québec, Canada has produced a staggering 440 different mineral species of which 73 were first found there as their Type Locality. The vast majority of those came from the famous Poudrette quarry and some represent the finest known examples of individual species. Genthelvite - an extremely rare beryllium zinc silicate sulphide is one species that was not found at Mont Saint-Hilaire first, but which occurs there in some of the best crystals known. This superb miniature specimen which comes from the superb systematic collection assembled by the brothers Martin and Michael Günther (1951-2007 & 1956-2021) features at least four really well-formed pale lemon yellow tetrahedral crystals reaching 4 mm on edge, but there are many more crystals evident. These Genthelvite crystals are associated with long blue-grey to black bladed Aegirine crystals penetrating through what appears to be white glassy Analcime. Other potentially interesting microcrystals are also present on this very rich Genthelvite-bearing specimen.