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, 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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