Carletonite is one of the very rare mineral species virtually unique to the Poudrette Quarry at Mt. St-Hilaire, Quebec. Intergrown crystals up to 2 cm make up this small cabinet sized large cluster, and the excellent, medium blue color is rich throughout. The few crystal faces have good luster and are striated. Even intergrown, these are a very respectable size, bordering on HUGE, for the species. Combined with the unique color, which is so strong it looks human-synthesized from a dye, and the presentation is incredible. This is an important specimen! The Poudrette Quarry, the TYPE LOCALITY, produced this find in the 1990s, and immediately they ranked as the world's best, and are irreplaceable.