Woodallite is a rare hydrated magnesium chromium chloride hydroxide mineral found in serpentinized ultramafic rocks. It typically forms as thin, yellow-to-brown platy crystals or aggregates within chromite-rich environments, specifically known from the Woodall mine in Western Australia.
Is this woodallite?
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 woodallite with a known reference. Woodallite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Woodallite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Woodallite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: yellow, brown.
- 5Look at form & habitCrystal system: trigonal. Typical habit: platy crystals.
Often confused with
Woodallite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside woodallite
Minerals reported to co-occur with woodallite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₆Cr₂(OH)₁₆Cl₂·4H₂O
- Mohs hardness
- 2-3
- Density
- 2.44 g/cm³
- Streak
- White
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Platy Crystals
- Cleavage
- Perfect Basal
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Ultramafic Rocks
- Typical price
- $50-300 per specimen
Where rockhounds find woodallite
Classic worldwide localities
- Woodall mine, Western Australia
Field-hunting tip
Look in ultramafic rocks country, the host setting where woodallite typically forms. If you start seeing stichtite, magnetite, serpentine in float, you are in the right ground. Field specimens usually show a platy crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find woodallite on the map
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