Bracewellite is a rare chromium oxyhydroxide mineral that occurs as small, dark needle-like crystals. It is structurally related to diaspore and is typically found in association with chromite deposits within ultramafic rock environments.
Is this bracewellite?
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 bracewellite with a known reference. Bracewellite sits at Mohs 6-7 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Bracewellite leaves a brown streak.
- 3Read the lusterHold the specimen under a strong light. Bracewellite typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: dark brown, black.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular crystals, prismatic crystals.
Often confused with
Bracewellite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Bracewellite leaves brown, Iron Ore leaves reddish-brown to black; luster reads submetallic on Bracewellite and metallic to submetallic on Iron Ore.
How to tell apart: Streak differs — Bracewellite leaves brown, Diaspore leaves white; luster reads submetallic on Bracewellite and vitreous on Diaspore.
Often found alongside bracewellite
Minerals reported to co-occur with bracewellite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CrO(OH)
- Mohs hardness
- 6-7
- Density
- 4.15 g/cm³
- Colors
- Streak
- Brown
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular Crystals, Prismatic Crystals
- Cleavage
- Perfect in One Direction
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Ultramafic Rocks, Hydrothermal Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find bracewellite
Classic worldwide localities
- Driekop Mine, South Africa
- Kempersai, Kazakhstan
Field-hunting tip
Look in ultramafic rocks, hydrothermal deposits country — that is the host setting where bracewellite typically forms. If you start seeing chromite, magnetite, goethite in float, you are in the right ground. Field specimens usually show a acicular crystals, prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find bracewellite on the map
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