Monteregianite-(Y) is an extremely rare silicate mineral typically found in the alkaline intrusive complexes of the Monteregian Hills. It usually occurs as small, clear to white tabular crystals or radiating sprays embedded within cavities of syenite or pegmatite. It is primarily sought after by advanced collectors of rare species and those focusing on the mineralogy of Mont Saint-Hilaire.
Is this monteregianite-(y)?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch monteregianite-(y) with a known reference. Monteregianite-(Y) sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Monteregianite-(Y) leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Monteregianite-(Y) typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, pale yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: tabular crystals, radiating aggregates.
Often confused with
Monteregianite-(Y) vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Eudialyte is the harder of the two (Mohs 5-6 vs. 3.5).
How to tell apart: Apophyllite is the harder of the two (Mohs 4.5-5 vs. 3.5); luster reads vitreous on Monteregianite-(Y) and vitreous to pearly on Apophyllite.
Often found alongside monteregianite-(y)
Minerals reported to co-occur with monteregianite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Na,K)₆(Y,Ca)₂Si₁₆O₃₈·10H₂O
- Mohs hardness
- 3.5
- Density
- 2.33 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular Crystals, Radiating Aggregates
- Cleavage
- None Observed
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Alkaline Igneous Rocks
- Typical price
- $50-300 per specimen
Where rockhounds find monteregianite-(y)
Classic worldwide localities
- Mont Saint-Hilaire, Quebec, Canada
Field-hunting tip
Look in alkaline igneous rocks country — that is the host setting where monteregianite-(y) typically forms. If you start seeing microcline, albite, aegirine in float, you are in the right ground. Field specimens usually show a tabular crystals, radiating aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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What rocks look like monteregianite-(y)?+
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Find monteregianite-(y) on the map
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