Nordstrandite is a rare polymorph of aluminum hydroxide often occurring as tiny, thin tabular crystals. It is primarily found in vugs within alkaline igneous rocks and is highly prized by micromounters for its distinct triclinic crystal habit.
Is this nordstrandite?
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 nordstrandite with a known reference. Nordstrandite sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Nordstrandite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Nordstrandite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: triclinic. Typical habit: tabular crystals, aggregates.
Often confused with
Nordstrandite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside nordstrandite
Minerals reported to co-occur with nordstrandite. 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
- 3
- Density
- 2.42 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Tabular Crystals, Aggregates
- Cleavage
- Perfect On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Alkaline Igneous Rocks, Hydrothermal Veins
- Typical price
- $20-100 thumbnail
Where rockhounds find nordstrandite
Classic worldwide localities
- Langesundsfjord, Norway
- Gunung Kasi, Indonesia
- Mont Saint-Hilaire, Canada
- Arkansas, USA
Field-hunting tip
Look in alkaline igneous rocks, hydrothermal veins country — that is the host setting where nordstrandite typically forms. If you start seeing gibbsite, dawsonite, analcime in float, you are in the right ground. Field specimens usually show a tabular crystals, aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find nordstrandite on the map
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