Phosphoferrite is a rare secondary phosphate mineral typically found in phosphate-rich granite pegmatites. It is often identified by its pale, often bluish-green prismatic crystals or crystalline crusts formed by the alteration of triphylite.
Is this phosphoferrite?
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 phosphoferrite with a known reference. Phosphoferrite sits at Mohs 3-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Phosphoferrite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Phosphoferrite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, pale yellow, pale green, bluish.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: prismatic crystals, granular aggregates, drusy crusts.
Often confused with
Phosphoferrite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside phosphoferrite
Minerals reported to co-occur with phosphoferrite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe²⁺₃(PO₄)₂·3H₂O
- Mohs hardness
- 3-4
- Density
- 3.55-3.61 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Prismatic Crystals, Granular Aggregates, Drusy Crusts
- Cleavage
- Good On {100}, Poor On {010}
- Rarity
- Rare
- Uses
- Collector, Scientific Research
- Host rock
- Granite Pegmatites
- Typical price
- $20-150 for thumbnail to miniature specimens
Where rockhounds find phosphoferrite
Classic worldwide localities
- Hagendorf, Bavaria, Germany
- Palermo Mine, New Hampshire, USA
- Bull Moose Mine, South Dakota, USA
- Mangualde, Portugal
Field-hunting tip
Look in granite pegmatites country, the host setting where phosphoferrite typically forms. If you start seeing triphylite, vivianite, ludlamite in float, you are in the right ground. Field specimens usually show a prismatic crystals, granular aggregates, drusy crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find phosphoferrite on the map
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