Dufrénite is a phosphate mineral commonly found in radial, botryoidal, or fibrous crusts with a distinct dark green color. It forms in the oxidized zones of phosphate-bearing pegmatites and is often associated with other secondary phosphate minerals.
Is this dufrénite?
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 dufrénite with a known reference. Dufrénite 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. Dufrénite leaves a light green streak.
- 3Read the lusterHold the specimen under a strong light. Dufrénite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: dark green, blackish green, olive green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: radial aggregates, botryoidal, fibrous, crusts.
Often confused with
Dufrénite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Dufrénite is noticeably harder (Mohs 3.5-4.5 vs. 1.5-2); streak differs — Dufrénite leaves light green, Vivianite leaves white to light blue.
How to tell apart: Streak differs — Dufrénite leaves light green, Strengite leaves white.
Often found alongside dufrénite
Minerals reported to co-occur with dufrénite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe²⁺Fe³⁺₄(PO₄)₃(OH)₅·2H₂O
- Mohs hardness
- 3.5-4.5
- Density
- 3.3-3.6 g/cm³
- Streak
- Light Green
- Luster
- Vitreous
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Radial Aggregates, Botryoidal, Fibrous, Crusts
- Cleavage
- Distinct in One Direction
- Rarity
- Uncommon
- Uses
- Collector, Mineralogical Specimen
- Host rock
- Phosphate-rich Pegmatites and Iron-rich Hydrothermal Deposits
- Typical price
- $15-150 per specimen depending on quality and habit
Where rockhounds find dufrénite
Classic worldwide localities
- Hagendorf, Bavaria, Germany
- Wheal Phoenix, Cornwall, England
- Rapid Creek, Yukon, Canada
- Midland, North Carolina, USA
Field-hunting tip
Look in phosphate-rich pegmatites and iron-rich hydrothermal deposits country — that is the host setting where dufrénite typically forms. If you start seeing rockbridgeite, cacoxenite, triplite in float, you are in the right ground. Field specimens usually show a radial aggregates, botryoidal, fibrous, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find dufrénite on the map
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