Segelerite is a rare calcium-magnesium-iron phosphate mineral typically found as small, vibrant green crystals in phosphate-rich pegmatites. It is highly sought after by mineral collectors for its aesthetic crystal habits and association with other rare secondary phosphate species.
Is this segelerite?
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 segelerite with a known reference. Segelerite sits at Mohs 4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Segelerite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Segelerite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: green, yellowish-green, olive-green.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: tabular to prismatic crystals, often as radial sprays or crusts.
Often confused with
Segelerite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside segelerite
Minerals reported to co-occur with segelerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaMgFe³⁺(PO₄)₂(OH)·4H₂O
- Mohs hardness
- 4
- Density
- 2.84 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular to Prismatic Crystals, Often as Radial Sprays or Crusts
- Cleavage
- Distinct On {100}
- Rarity
- Rare
- Uses
- Collector, Mineralogical Research
- Host rock
- Phosphate-rich Granite Pegmatites
- Typical price
- $50-300 per specimen depending on size and quality
Where rockhounds find segelerite
Classic worldwide localities
- Tip Top mine, Custer County, South Dakota, USA
- Newry, Maine, USA
Field-hunting tip
Look in phosphate-rich granite pegmatites country — that is the host setting where segelerite typically forms. If you start seeing montgomeryite, overite, englishite in float, you are in the right ground. Field specimens usually show a tabular to prismatic crystals, often as radial sprays or crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find segelerite on the map
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