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, 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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