Fluornatrocoulsellite is a rare member of the eudialyte group found in alkaline igneous complexes. Collectors identify it by its specific trigonal habit and its association with other rare alkaline minerals, though it is often indistinguishable from eudialyte without chemical analysis.
Is this fluornatrocoulsellite?
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 fluornatrocoulsellite with a known reference. Fluornatrocoulsellite sits at Mohs 5-6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Fluornatrocoulsellite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Fluornatrocoulsellite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: pink, reddish, brown.
- 5Look at form & habitCrystal system: trigonal. Typical habit: equant crystals, granular aggregates.
Often confused with
Fluornatrocoulsellite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside fluornatrocoulsellite
Minerals reported to co-occur with fluornatrocoulsellite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₁₅Ca₆(Fe²⁺)₃Zr₃Si₂₆O₇₂(OH,F)₄
- Mohs hardness
- 5-6
- Density
- 2.8-3.0 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Equant Crystals, Granular Aggregates
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Scientific Research
- Host rock
- Alkaline Igneous Rocks, Pegmatites
- Typical price
- $50-300 per specimen
Where rockhounds find fluornatrocoulsellite
Classic worldwide localities
- Mont Saint-Hilaire, Canada
- Kola Peninsula, Russia
Field-hunting tip
Look in alkaline igneous rocks, pegmatites country — that is the host setting where fluornatrocoulsellite typically forms. If you start seeing nepheline, microcline, aegirine in float, you are in the right ground. Field specimens usually show a equant crystals, granular aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify fluornatrocoulsellite?+
Where is fluornatrocoulsellite found?+
How much is fluornatrocoulsellite worth?+
What rocks look like fluornatrocoulsellite?+
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