Crandallite is a phosphate mineral that often forms interesting botryoidal or crusty habit formations. It is commonly found as a secondary mineral in phosphate-rich environments and is frequently associated with wavellite or variscite.
Is this crandallite?
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 crandallite with a known reference. Crandallite sits at Mohs 5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Crandallite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Crandallite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, yellow, gray, brown.
- 5Look at form & habitCrystal system: trigonal. Typical habit: massive, botryoidal, spherical crusts, fibrous aggregates.
Often confused with
Crandallite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside crandallite
Minerals reported to co-occur with crandallite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaAl₃(PO₄)₂(OH)₅·H₂O
- Mohs hardness
- 5
- Density
- 2.7-2.9 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Massive, Botryoidal, Spherical Crusts, Fibrous Aggregates
- Cleavage
- Perfect On {0001}
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- Phosphate-rich Sedimentary Deposits, Hydrothermal Veins, Weathered Igneous Rocks
- Typical price
- $10-50 for small specimens
Where rockhounds find crandallite
Classic worldwide localities
- USA
- Australia
- Germany
- France
Field-hunting tip
Look in phosphate-rich sedimentary deposits, hydrothermal veins, weathered igneous rocks country — that is the host setting where crandallite typically forms. If you start seeing wavellite, variscite, goethite in float, you are in the right ground. Field specimens usually show a massive, botryoidal, spherical crusts, fibrous aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find crandallite on the map
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