New finds in 2016 at the Poudrette Quarry, Mont-Saint-Hilaire, Quebec Province, Canada
In 2016, new mineral cavities and/or fractures were opened at the Poudrette Quarry, Mont-Saint-Hilaire. The specimens were discovered during numerous private visits at the quarry. In 2020, Collection Arkane purchased these specimens to make them available to the collector community.
The specimens were found in separate small cavities and/or fractures in the walls of the quarry. The quarry at Mont-Saint-Hilaire is one the most prolific localities in the World with currently 430 approved mineral species identified of which 69 are type locality minerals (ref. mindat.org). See our previous blogs about this locality.
The cavities content may be divided into two discoveries: rhodochrosite with or without aegirine and/or polylithionite; gaidonnayite, bastnasite-(Ce), analcime, ankerite, quartz, gmelinite and/or other species.
The rhodochrosite specimens are mostly non-descript aggregates of dark red crystals, sometimes associated with black prismatic aegirine and weakly fluorescent polylithionite crystals. Rarely, other minerals such as sphalerite and catapleiite may also be present.
Another group of small cavities provided a large mixture of gaidonnayite, bastnasite-(Ce), analcime, ankerite, quartz, gmelinite-Na and/or other species. These species occur rarely by themselves but are most often associated with each other in the cavities. The type locality species gaidonnayite is present along with the dominant species bastnasite-(Ce) and ankerite on some of the specimens. Another very interesting association are colorless to smoky gemmy quartz crystals literally covered with highly gemmy colorless well formed analcime crystals. The analcime crystals are so gemmy they are barely visible even to the naked eyes and quite difficult to photograph. A personal communication of Gilles Haineault indicated important zeolite species often are quite exclusive of each other in a specific cavity or fracture, meaning that analcime will dominate in some cavities while natrolite in others, and son on.
Collectors who wish to further investigate the geology and mineralogy of the Poudrette Quarry at Mont-Saint-Hilaire and find excellent photographs of mineral species from this locality are invited to consult the mindat.org website as well as the Mineralogical Record special publication on Mont-Saint-Hilaire (volume 21, number 4, 1990). Also, you may wish to consult Gilles Haineault’s book about some specimens of his personal collection, and the Mineralogical Association of Canada Special Publication number 14, certainly the most comprehensive publication about the history, geology and mineralogy of this locality.
Text published: December 2020.