Hedegaardite is a very rare phosphate mineral found in specific sedimentary environments where organic matter interacts with phosphate-rich groundwater. It typically forms small, prismatic yellow crystals that are highly sensitive to dehydration and light exposure, often requiring careful storage.
Is this hedegaardite?
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 hedegaardite with a known reference. Hedegaardite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Hedegaardite leaves a yellowish-white streak.
- 3Read the lusterHold the specimen under a strong light. Hedegaardite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, brownish-yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals.
Often confused with
Hedegaardite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Hedegaardite is noticeably harder (Mohs 3 vs. 1.5-2); streak differs, so Hedegaardite leaves yellowish-white, Vivianite leaves white to light blue.
How to tell apart: Hedegaardite is noticeably harder (Mohs 3 vs. 1.5-2); streak differs, so Hedegaardite leaves yellowish-white, Metavivianite leaves greenish-white.
Often found alongside hedegaardite
Minerals reported to co-occur with hedegaardite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (NH₄)Mn₂Fe₂(PO₄)₃·3H₂O
- Mohs hardness
- 3
- Density
- 2.81 g/cm³
- Colors
- Streak
- Yellowish-white
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals
- Cleavage
- Perfect On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Sedimentary Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find hedegaardite
Classic worldwide localities
- Skarlev, Denmark
Field-hunting tip
Look in sedimentary deposits country, the host setting where hedegaardite typically forms. If you start seeing vivianite, siderite, quartz in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find hedegaardite on the map
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