Mountkeithite is a rare layered double hydroxide mineral typically found in serpentinized nickel-rich ultramafic environments. Collectors generally find it as small, white to pale yellow scaly or platy aggregates forming thin crusts or films on matrix material.
Is this mountkeithite?
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 mountkeithite with a known reference. Mountkeithite 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. Mountkeithite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Mountkeithite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: white, pale yellow.
- 5Look at form & habitCrystal system: trigonal. Typical habit: platy crystals, scaly aggregates.
Often confused with
Mountkeithite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside mountkeithite
Minerals reported to co-occur with mountkeithite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Mg,Ni)₈Cr₂(OH)₁₈(CO₃,SO₄)·nH₂O
- Mohs hardness
- 2
- Density
- 2.05 g/cm³
- Colors
- Streak
- White
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Platy Crystals, Scaly Aggregates
- Cleavage
- Perfect Basal
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Nickel-sulfide Ore Deposits in Serpentinized Ultramafic Rocks
- Typical price
- $20-100 for small thumbnail specimens
Where rockhounds find mountkeithite
Classic worldwide localities
- Mount Keith Nickel Mine, Western Australia
Field-hunting tip
Look in nickel-sulfide ore deposits in serpentinized ultramafic rocks country — that is the host setting where mountkeithite typically forms. If you start seeing serpentine, magnesite, dolomite in float, you are in the right ground. Field specimens usually show a platy crystals, scaly aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find mountkeithite on the map
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