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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: green, chartreuse, colorless.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: prismatic, striated.
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
- 2.67 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Orthorhombic
- Crystal habit
- Prismatic, striated
- Cleavage
- On {010}, perfect
- Rarity
- Rare
- Uses
- Collector, Mineralogical research
- Host rock
- A rare alteration product of triphylite in zoned complex granite pegmatites
Where rockhounds find segelerite
Classic worldwide localities
- Tip Top mine, 8.5 km southwest of Custer, Custer Co., South Dakota, USA
- Milgun Station, Western Australia
- Mangualde pegmatite, near Mesquitela, and at Belmonte, south of Guarda, Portugal
- Hagendorf, Bavaria, Germany
Field-hunting tip
Where it forms: A rare alteration product of triphylite in zoned complex granite pegmatites. If you start seeing ferrisicklerite-rockbridgeite, collinsite, hydroxylapatite in float, you are in the right ground. Typical habit: prismatic, striated. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify segelerite?+
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What rocks look like segelerite?+
What minerals are found with segelerite?+
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Find segelerite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
