Bayerite is a rare polymorph of aluminum hydroxide often found in bauxite deposits and soils. It typically occurs as small, delicate, white platy crystals or fine-grained masses that are visually indistinguishable from its more common cousin, gibbsite, without laboratory analysis.
Is this bayerite?
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 bayerite with a known reference. Bayerite sits at Mohs 2.5-3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Bayerite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Bayerite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals, fine-grained aggregates.
Often confused with
Bayerite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside bayerite
Minerals reported to co-occur with bayerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Al(OH)₃
- Mohs hardness
- 2.5-3
- Density
- 2.53 g/cm³
- Streak
- White
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Platy Crystals, Fine-grained Aggregates
- Cleavage
- Perfect On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Bauxite Deposits and Secondary Weathering Zones
- Typical price
- $20-100 thumbnail
Where rockhounds find bayerite
Classic worldwide localities
- Bauxite deposits of Southern Ural Mountains, Russia
- Northern Ireland
- Germany
Field-hunting tip
Look in bauxite deposits and secondary weathering zones country — that is the host setting where bayerite typically forms. If you start seeing gibbsite, boehmite, hematite in float, you are in the right ground. Field specimens usually show a platy crystals, fine-grained aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify bayerite?+
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Find bayerite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
