Francon Quarry is the locality that made weloganite a collector mineral rather than merely a chemical curiosity. The species, Na2Sr3Zr(CO3)6·3H2O, is a hydrated sodium-strontium-zirconium carbonate, and Francon is its type locality. What distinguishes Francon material is not only rarity, but presence: straw-yellow to lemon-yellow crystals, pseudo-hexagonal in outline, often deeply striated and subtly swollen along the prism, set in vugs with quartz, calcite, dawsonite, fluorite, strontianite, and other minerals from one of Canada’s most singular urban mineral deposits.
Photo: Wikimedia Commons
The setting is almost improbable: a world-class rare-mineral locality in the middle of Montréal. Francon was a limestone quarry in the St-Michel district, but the weloganite did not come from ordinary limestone. It came from cavities in an alkalic, dawsonite-rich, carbonatized sill related to the Monteregian alkaline igneous province. Those cavities produced an exceptionally unusual carbonate assemblage rich in strontium, barium, sodium, aluminum, zirconium, fluorine, and carbonate species. The result was a locality that yielded ten type-locality species and more than eighty valid minerals, with weloganite as the signature prize.
Photo: Wikimedia Commons
For collectors, the appeal is instantly visual. Fine Francon weloganites have a soft honey or lemon color, glassy to somewhat pearly luster, and a stacked, pagoda-like architecture that makes them recognizable even before a label is read. The best crystals show sharp pseudo-hexagonal outlines, strong horizontal growth striations, undulating crystal width, and crisp terminations ranging from blunt pyramidal tips to flatter pedions. Matrix specimens are especially desirable, because they preserve the mineral in the vuggy assemblage that proves its locality and gives the crystals scale, context, and contrast.
Historically, weloganite also carries unusual Canadian weight. Ann P. Sabina of the Geological Survey of Canada recognized the unfamiliar mineral during work in the Montréal area in 1966, and the species was described in 1968 by Sabina, J. L. Jambor, and A. G. Plant. It was named for Sir William Edmond Logan, founder and first director of the Geological Survey of Canada. In collecting terms, it is one of those rare cases where the type locality is also the standard for display-quality specimens.
Search for specimens: View all weloganite specimens from Francon Quarry, Montréal, Canada
Francon Quarry lies at 3701 Rue Jarry Est in Montréal, in the St-Michel area of the city. The quarry is inactive, city-owned, and no longer a collecting locality in the practical sense; modern references describe it as used for winter snow dumping. For collectors, Francon material is therefore almost entirely historical: specimens collected during quarry operation, old dealer stock, collection dispersals, and pieces preserved in museums.
Geologically, the quarry cut Ordovician limestone that had been intruded by alkaline sills and dikes genetically tied to the Monteregian Hills, the same broader alkaline province that includes Mount Royal and Mont Saint-Hilaire. Weloganite occurred in cavities in the St-Michel sill, described in the original work as a 5- to 10-foot alkalic sill and in later summaries as roughly 2 m thick. The rock is widely discussed as a dawsonite-rich carbonatized phonolite or carbonatite-like sill, and its mineralogy is notably unlike that of other Montréal-area quarries.
The quarry became mineralogically famous after the 1966 discovery of weloganite. The 1968 description of the species established Francon as the type locality and brought attention to the rest of the pocket mineralogy. Subsequent work documented a remarkable suite of new species, including dresserite, hydrodresserite, strontiodresserite, sabinaite, franconite, montroyalite, and voggite, with doyleite and hochelagaite also listed as co-type-locality species. The quarry ranks behind Mont Saint-Hilaire among Canada’s most prolific type localities.
Production of collector specimens was tied to quarry activity. As blasting exposed fresh sections of sill, collectors and researchers could recover vug material. By the time quarrying stopped, the important weloganite-producing exposures had become historical. Modern “new” Francon weloganites generally mean old specimens newly released from private collections, not newly collected material.
Notable finds range from millimetric crystals for systematic suites to cabinet pieces with several sharp yellow crystals on quartz-lined matrix. The locality’s reputation rests on the fact that Francon produced weloganite as attractive, freestanding crystals, not just microscopic grains or inclusions. Later summaries of the locality cite crystals up to about 6 cm; mineral data sheets give an exceptional upper limit of 10 cm. For most collectors, however, a sharp 5–15 mm crystal on matrix is already a serious Francon specimen.
Classic Francon weloganite forms pseudo-hexagonal prisms in a triclinic mineral made visually hexagonal by repeated twinning. The crystals are rarely simple straight columns. They tend to be grooved, horizontally striated, and irregular in width, with a pinched-and-swollen outline caused by oscillatory growth. Some crystals resemble stacked plates; others look like small pagodas, barrels, or tapering trumpets.
Color is one of the key locality attributes. The most desirable Francon crystals are pale straw, lemon yellow, honey yellow, or amber. Colorless, white, grayish, and greenish examples also occur, and many crystals are partly translucent rather than fully transparent. Thin fragments can be colorless; basal sections may show zoning from white to yellow. Collectors usually prefer yellow crystals with some translucency, especially when the color is natural-looking rather than dull, chalky, or overly altered.
Terminations are variable. Some crystals taper into blunt pyramidal ends; others finish in a flat pedion, sometimes wider than the main prism. The prism faces are commonly strongly striated and grooved, a feature that should be read as normal growth character, not damage. The best examples retain crisp face junctions, clean terminations, and a visible pseudo-hexagonal cross-section.
The most typical collector size range is from a few millimeters to about 1–2 cm. Fine crystals above 2 cm are much more desirable, and matrix specimens with multiple well-positioned crystals are scarce. The original description noted crystals from about 2 mm to more than 3 cm along the elongation, while later locality summaries record still larger exceptional crystals.
Associations matter at Francon. Quartz-lined vugs make especially attractive hosts, providing sparkle and contrast against yellow weloganite. Calcite and dawsonite are important classic associates, and Francon material may also include strontianite, fluorite, baryte, celestine, siderite, dolomite, pyrite, marcasite, galena, sphalerite, zircon, anatase, and rare barium-aluminum carbonate minerals. Dresserite and related species add further locality interest, though they should not be assumed unless visually or analytically confirmed.
Quality factors are straightforward but exacting: sharpness, natural yellow color, translucency, intact termination, undamaged edges, and convincing matrix are the hierarchy. A single well-formed yellow crystal on matrix usually outranks a larger but chalky, incomplete, or detached crystal. Because the quarry is closed, provenance also matters. Old labels from Canadian collectors, Geological Survey circles, Montréal collectors, or reputable dealers add real value.
Weloganite from Francon is also known for luminescent behavior. Triboluminescence has been described as faint blue, and shortwave ultraviolet response in Francon specimens has been reported in pale orange to orange tones in the locality literature. UV response, however, should be treated as a supporting observation rather than a standalone identification tool, because associated Francon minerals may fluoresce differently and coatings can complicate interpretation.
No recurring, well-documented trade in fabricated Francon weloganite comparable to the classic fake problems of dyed quartz, glued crocoite, or lab-grown “specimens” is established in the mineral literature. The main authenticity concerns are more subtle: wrong locality, reattached crystals, repaired matrix, mislabeled associated minerals, and overly ambitious claims about size, rarity, or old collection history.
Locality is the first concern. Francon is the type locality and the benchmark for display-quality weloganite, but weloganite is also known from other Québec localities, including Mont Saint-Hilaire and a limestone quarry east of Montréal. A specimen simply labeled “Montréal” or “Québec” deserves closer scrutiny. For a serious Francon purchase, the label should ideally say Francon Quarry, St-Michel or Montréal, Québec, Canada, and older labels or collection history should be preserved.
Repairs are possible and should be expected in the market for fragile, vug-grown classics. Weloganite has perfect basal cleavage, modest hardness, and conchoidal fracture; broken and reattached crystals are plausible. Examine the base of each crystal under magnification for glue films, discontinuous striations, suspiciously clean breaks, or a crystal sitting at an unnatural angle on unrelated matrix. UV light can sometimes reveal adhesive, but it can also be confused by natural fluorescence from associated minerals.
Condition issues are common. Look for bruised terminations, missing pedions, chipped prism edges, cleaved bases, and dull or chalky surfaces. A white coating can be natural alteration or a post-collection surface change, but it reduces eye appeal when it masks luster and color. Aggressive cleaning is another risk: acid or chemical over-cleaning can leave faces frosted, etched, or unnaturally matte. A fine Francon weloganite should not look polished; natural faces carry growth striations, subtle zoning, and a glassy to vitreous surface where fresh.
Loose crystals are less desirable than matrix examples unless unusually sharp, large, or historically documented. Matrix adds both aesthetics and evidence: quartz, calcite, dawsonite-rich material, and typical Francon vug textures help support the attribution. Conversely, a bright crystal perched on matrix with no geological continuity should be treated cautiously.
Rarity is real but tiered. Small, pale, or partly damaged Francon weloganites appear periodically, especially from old collections. Fine yellow matrix specimens with sharp crystals over 1 cm are much less common. Large, translucent, well-terminated examples with strong color and historic provenance are classic Canadian rarities and should be evaluated with the same care given to other closed-locality type specimens.
Market availability is intermittent rather than steady. The quarry is not a modern source, so specimens appear through dealer inventories, auctions, collection dispersals, and old Canadian material. A good label is not a luxury; for this locality, provenance is part of the specimen.
The discovery story begins not in a remote mountain district, but in Montréal traffic and limestone dust. In July 1966, Ann P. Sabina was working on what would become a Geological Survey of Canada collector guide covering the route from Ontario to Lac-Saint-Jean. Montréal Island limestone was not famous for rare crystallized minerals. Earlier geologists had noted igneous sills and dikes in the area, but the mineralogy had not drawn the kind of attention that later surrounded Francon.
Sabina’s first visit to the quarry was not a triumphant walk into an open collecting ground. According to later biographical accounts, she was refused access for “security and insurance reasons.” Her solution was practical and very Sabina: she paid a young man working at the quarry 5 dollars to bring her samples. The same account notes that the average hourly wage for a Québec laborer at the time was $2.26, so this was not a token errand. It was a small field investment that returned one of Canada’s great mineral discoveries.
On that first inspection of the thick igneous sill, cavities with crystallized minerals caught her attention. Among them was something unfamiliar, and its color was the hook. Sabina later recalled that it was the mineral’s “splendid golden color” that drew her eye. Back at the Geological Survey of Canada laboratory, Sabina, J. L. Jambor, and A. G. Plant established that the material was new. The 1968 description introduced weloganite as a new strontium-zirconium carbonate, named for Sir William Edmond Logan.
The name carried a historical symmetry that collectors still appreciate. Logan had founded the Geological Survey of Canada in 1842, and the Survey had been established in Montréal before later moving to Ottawa. More than a century later, a mineral found beneath Montréal’s urban limestone industry would honor him. Francon, once an ordinary working quarry, became a mineralogical landmark.
Sabina’s Francon work also became part of a larger career that shaped Canadian collecting. She spent decades building mineral powder-diffraction resources and writing the “Rocks and Minerals for the Collector” guidebooks that put Canadian localities into the hands of amateurs and professionals alike. Later accounts credit her with identifying nine of Francon’s ten new mineral species, and note that local news at the time did not properly credit her for the discovery. The specimens, however, kept the record. Each good Francon weloganite still carries the trace of that first yellow flash in a Montréal quarry wall.
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