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Mont Saint-Hilaire in Québec, Canada is one of the most famous and important mineralogical localities in the world, particularly for rare species with exotic chemistries. Ancylite-(Ce) - cerium strontium carbonate hydroxide hydrate - is reported from a reasonable number of sites worldwide but nearly always in microcrystals. Mont Saint-Hilaire is unusual in that it has produced exceptionally large crystals, in the 3 to 5 mm size range. This thumbnail crystal from the superb systematic collection assembled by the brothers Martin and Michael Günther (1951-2007 & 1956-2021) is colossal. At 2.2 cm in length, it is ginormous. It might be off-matrix, but it is worldclass for its size and maintains an excellent elongated crystal shape.
5 x 5 x 22 mm