Hiortdahlite is a rare sorosilicate mineral typically found in nepheline syenite pegmatites. Collectors look for its characteristic pale yellow to colorless tabular crystals, which are often associated with other rare alkaline accessory minerals.
Is this hiortdahlite?
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 hiortdahlite with a known reference. Hiortdahlite sits at Mohs 5-5.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Hiortdahlite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Hiortdahlite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellowish-brown, colorless, white.
- 5Look at form & habitCrystal system: triclinic. Typical habit: tabular crystals, prismatic, granular.
Often confused with
Hiortdahlite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside hiortdahlite
Minerals reported to co-occur with hiortdahlite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ca,Na)₃Zr(Si₂O₇)(O,OH,F)₂
- Mohs hardness
- 5-5.5
- Density
- 3.23-3.32 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Tabular Crystals, Prismatic, Granular
- Cleavage
- Distinct On {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Syenite Pegmatites
- Typical price
- $50-300 per specimen
Where rockhounds find hiortdahlite
Classic worldwide localities
- Langesundsfjord, Norway
- Kola Peninsula, Russia
- Mont Saint-Hilaire, Canada
Field-hunting tip
Look in syenite pegmatites country — that is the host setting where hiortdahlite typically forms. If you start seeing nepheline, aegirine, eudialyte in float, you are in the right ground. Field specimens usually show a tabular crystals, prismatic, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify hiortdahlite?+
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What rocks look like hiortdahlite?+
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Find hiortdahlite on the map
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