Natrodufrénite is a rare phosphate mineral typically found as radiating fibrous aggregates or crusts in phosphate-rich zones of granitic pegmatites. Collectors look for its characteristic deep green color and acicular crystal growth, often associated with other secondary iron-phosphate minerals.
Is this natrodufrénite?
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 natrodufrénite with a known reference. Natrodufrénite sits at Mohs 4-5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Natrodufrénite leaves a light green streak.
- 3Read the lusterHold the specimen under a strong light. Natrodufrénite typically shows a vitreous to dull luster.
- 4Match the color rangeCompare against the expected color range: green, yellowish-green, dark green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fibrous, radiating aggregates, crusts.
Often confused with
Natrodufrénite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Luster reads vitreous to dull on Natrodufrénite and vitreous on Dufrénite.
How to tell apart: Streak differs — Natrodufrénite leaves light green, Rockbridgeite leaves greenish-brown; luster reads vitreous to dull on Natrodufrénite and vitreous on Rockbridgeite.
How to tell apart: Streak differs — Natrodufrénite leaves light green, Kidwellite leaves yellowish-white; luster reads vitreous to dull on Natrodufrénite and vitreous on Kidwellite.
Often found alongside natrodufrénite
Minerals reported to co-occur with natrodufrénite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaFe²⁺Fe³⁺₅(PO₄)₄(OH)₆·2H₂O
- Mohs hardness
- 4-5
- Density
- 3.3-3.4 g/cm³
- Streak
- Light Green
- Luster
- Vitreous to Dull
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous, Radiating Aggregates, Crusts
- Cleavage
- None Observed
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Phosphate-rich Granitic Pegmatites
- Typical price
- $20-150 thumbnail
Where rockhounds find natrodufrénite
Classic worldwide localities
- Hagendorf-Pleystein pegmatite, Germany
- Tip Top Mine, South Dakota, USA
- Palmas, Brazil
Field-hunting tip
Look in phosphate-rich granitic pegmatites country — that is the host setting where natrodufrénite typically forms. If you start seeing triphylite, rockbridgeite, vivianite in float, you are in the right ground. Field specimens usually show a fibrous, radiating aggregates, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find natrodufrénite on the map
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