Motukoreaite is a rare layered double hydroxide mineral typically found as white or pale blue platy, micaceous crystals in volcanic settings. It is often identified in basaltic cavities and is known for its perfect basal cleavage, similar to other members of the hydrotalcite group.
Is this motukoreaite?
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 motukoreaite with a known reference. Motukoreaite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Motukoreaite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Motukoreaite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: white, pale blue, greenish.
- 5Look at form & habitCrystal system: trigonal. Typical habit: platy crystals, fine-grained aggregates.
Often confused with
Motukoreaite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside motukoreaite
Minerals reported to co-occur with motukoreaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- [Na,Ca]₀.₇[Mg,Al,Fe²⁺]₄(OH)₁₂[CO₃,SO₄]₀.₈·3H₂O
- Mohs hardness
- 2
- Density
- 2.05 g/cm³
- Streak
- White
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Platy Crystals, Fine-grained Aggregates
- Cleavage
- Perfect Basal
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Volcanic Rocks, Hydrothermal Cavities
- Typical price
- $20-150 thumbnail specimens
Where rockhounds find motukoreaite
Classic worldwide localities
- Motukorea Island, New Zealand
- Langban, Sweden
- Mont Saint-Hilaire, Canada
Field-hunting tip
Look in volcanic rocks, hydrothermal cavities country — that is the host setting where motukoreaite typically forms. If you start seeing calcite, phillipsite, chabazite 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
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Find motukoreaite on the map
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