Imogolite is a rare aluminosilicate clay mineral that typically forms as extremely fine, hollow nanotubes in volcanic soils. It is rarely found in macroscopic crystals and is primarily studied for its unique nanostructure and high surface area in geological and materials science.
Is this imogolite?
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 imogolite with a known reference. Imogolite sits at Mohs 1 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Imogolite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Imogolite typically shows a dull luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, pale yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: thread-like, fibrous, or as clay-sized aggregates.
Often confused with
Imogolite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Allophane is the harder of the two (Mohs 3 vs. 1); luster reads dull on Imogolite and vitreous on Allophane.
How to tell apart: Halloysite is the harder of the two (Mohs 2-2.5 vs. 1); luster reads dull on Imogolite and pearly on Halloysite.
Often found alongside imogolite
Minerals reported to co-occur with imogolite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Al₂SiO₃(OH)₄
- Mohs hardness
- 1
- Density
- 2.1 g/cm³
- Streak
- White
- Luster
- Dull
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Thread-like, Fibrous, Or as Clay-sized Aggregates
- Cleavage
- None
- Rarity
- Uncommon
- Uses
- Scientific Research, Catalysis
- Host rock
- Weathered Volcanic Ash Soils (andosols)
- Typical price
- n/a
Where rockhounds find imogolite
Classic worldwide localities
- Japan
- New Zealand
- United States
- France
Field-hunting tip
Look in weathered volcanic ash soils (andosols) country — that is the host setting where imogolite typically forms. If you start seeing allophane, gibbsite, kaolinite in float, you are in the right ground. Field specimens usually show a thread-like, fibrous, or as clay-sized aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find imogolite on the map
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