Ferrowyllieite is a rare phosphate mineral primarily found in complex granite pegmatites. It typically appears as green to yellow-green granular or crystalline masses and is often identified via chemical analysis due to its similarity to other members of the wyllieite group.
Is this ferrowyllieite?
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 ferrowyllieite with a known reference. Ferrowyllieite 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. Ferrowyllieite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Ferrowyllieite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: green, yellow-green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: granular, massive, prismatic crystals.
Often confused with
Ferrowyllieite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside ferrowyllieite
Minerals reported to co-occur with ferrowyllieite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₂Fe²⁺₂Fe²⁺(PO₄)₃
- Mohs hardness
- 4-5
- Density
- 3.8-3.9 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Granular, Massive, Prismatic Crystals
- Cleavage
- Distinct On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
- Typical price
- $50-300 per specimen
Where rockhounds find ferrowyllieite
Classic worldwide localities
- Palmeira pegmatite, Brazil
- Tip Top mine, South Dakota, USA
- Norrö, Sweden
Field-hunting tip
Look in granite pegmatites country — that is the host setting where ferrowyllieite typically forms. If you start seeing triphylite, albite, quartz in float, you are in the right ground. Field specimens usually show a granular, massive, prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferrowyllieite?+
Where is ferrowyllieite found?+
How much is ferrowyllieite worth?+
What rocks look like ferrowyllieite?+
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Find ferrowyllieite on the map
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