Planerite is a relatively rare hydrated aluminum phosphate mineral that typically forms as botryoidal crusts or radial aggregates. Collectors often find it as a secondary mineral in phosphate-rich environments, frequently associated with variscite and wavellite. It is best identified by its distinct habit and occurrence within weathered aluminum-bearing phosphate deposits.
Is this planerite?
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 planerite with a known reference. Planerite 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. Planerite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Planerite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, blue, green, yellow.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: botryoidal, crusts, radial aggregates.
Often confused with
Planerite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads vitreous on Planerite and waxy on Variscite.
How to tell apart: Wardite is the harder of the two (Mohs 5 vs. 4).
How to tell apart: Crandallite is the harder of the two (Mohs 5 vs. 4).
Often found alongside planerite
Minerals reported to co-occur with planerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Al₆(PO₄)₄(OH)₆·10H₂O
- Mohs hardness
- 4
- Density
- 2.81 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Tetragonal
- Crystal habit
- Botryoidal, Crusts, Radial Aggregates
- Cleavage
- Good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Phosphate-rich Hydrothermal Veins and Secondary Oxidation Zones
- Typical price
- $20-150 for small specimens
Where rockhounds find planerite
Classic worldwide localities
- Dalnegorsk, Russia
- Dodford, England
- Montebras, France
- Montgomery County, Arkansas, USA
Field-hunting tip
Look in phosphate-rich hydrothermal veins and secondary oxidation zones country, the host setting where planerite typically forms. If you start seeing variscite, wavellite, crandallite in float, you are in the right ground. Field specimens usually show a botryoidal, crusts, radial aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find planerite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
