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 3.5-4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: green.
- 3Read the lusterHold the specimen under a strong light. Luster: silky.
- 4Match the color rangeCompare against the expected color range: light blue green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fibrous, radial, spherical.
Often confused with
Natrodufrénite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads silky on Natrodufrénite and vitreous to silky on Dufrénite.
How to tell apart: Streak differs, so Natrodufrénite leaves green, Rockbridgeite leaves greenish gray; luster reads silky on Natrodufrénite and vitreous to dull on Rockbridgeite.
How to tell apart: Streak differs, so Natrodufrénite leaves green, Kidwellite leaves yellow.
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
- NaFeFe₅(PO₄)₄O(OH)₅(H₂O)₂
- Mohs hardness
- 3.5-4.5
- Density
- 3.20 g/cm³
- Colors
- Light blue green
- Streak
- Green
- Luster
- Silky
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous, radial, spherical
- Cleavage
- None observed
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A low-temperature secondary mineral
Where rockhounds find natrodufrénite
Classic worldwide localities
- Lone Star copper deposit, Safford district, Graham Co., Arizona, USA
- Rochefort-en-Terre, Morbihan, France
- Pinilla de Fermoselle pegmatite, Zamora, Spain
- Mt. Oxide mine, Mt. Isa district, Queensland, Australia
- Lake Boga granite quarry, near Swan Hill, Victoria, Australia
- Broken Hill, New South Wales, Australia
Field-hunting tip
Where it forms: A low-temperature secondary mineral. If you start seeing cyrilovite, goethite in float, you are in the right ground. Typical habit: fibrous, radial, spherical. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify natrodufrénite?+
Where is natrodufrénite found?+
What rocks look like natrodufrénite?+
What minerals are found with natrodufrénite?+
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Find natrodufrénite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
