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, 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.
