Lalondeite is a rare silicate mineral primarily found in the nepheline syenite pegmatites of Mont Saint-Hilaire, Canada. It forms small, colorless to white prismatic crystals and is frequently associated with other rare alkaline minerals like serandite and pectolite. Due to its extremely limited locality, it is highly sought after by systematic mineral collectors.
Is this lalondeite?
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 lalondeite with a known reference. Lalondeite sits at Mohs 5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Lalondeite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Lalondeite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: triclinic. Typical habit: prismatic crystals.
Often confused with
Lalondeite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside lalondeite
Minerals reported to co-occur with lalondeite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Na,Ca)₆(Si₆O₁₅(OH)₂)(OH,F)₂·3H₂O
- Mohs hardness
- 5
- Density
- 2.71 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Prismatic Crystals
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Alkaline Igneous Intrusive Complexes
- Typical price
- $50-300 per specimen
Where rockhounds find lalondeite
Classic worldwide localities
- Poudrette quarry, Mont Saint-Hilaire, Quebec, Canada
Field-hunting tip
Look in alkaline igneous intrusive complexes country — that is the host setting where lalondeite typically forms. If you start seeing pectolite, serandite, analcime in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find lalondeite on the map
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