Wyllieite is a rare phosphate mineral typically found as a primary or secondary phase in complex granite pegmatites. It is often identified by its distinct green to brownish hues and its occurrence alongside other phosphate minerals like triphylite. Collectors generally look for it in classic pegmatite localities where it forms small, well-defined prismatic crystals or massive aggregates.
Is this wyllieite?
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 wyllieite with a known reference. Wyllieite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Wyllieite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Wyllieite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: dark green, yellow-green, brownish, black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, massive, granular.
Often confused with
Wyllieite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside wyllieite
Minerals reported to co-occur with wyllieite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₂Mn²⁺(Fe²⁺,Fe³⁺)Al(PO₄)₃
- Mohs hardness
- 3.5
- Density
- 3.55 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals, Massive, Granular
- Cleavage
- Poor
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
- Typical price
- $20-150 thumbnail, $200-500 cabinet
Where rockhounds find wyllieite
Classic worldwide localities
- Palermo No. 1 mine, New Hampshire, USA
- Tip Top mine, South Dakota, USA
- Mangualde, Portugal
- Brumado, Brazil
Field-hunting tip
Look in granite pegmatites country — that is the host setting where wyllieite typically forms. If you start seeing triphylite, quartz, albite in float, you are in the right ground. Field specimens usually show a prismatic crystals, massive, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
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How much is wyllieite worth?+
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Find wyllieite on the map
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