Tredouxite is a rare nickel antimony oxide, typically black. It occurs in a podiform nickeliferous deposit in altered ultramafic rocks. It is associated with trevorite and bottinoite. It was first described from Bon Accord Ni-oxide deposit, southeast of Nelspruit, Republic of South Africa.
Is this tredouxite?
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 tredouxite with a known reference. Tredouxite sits at Mohs 3-3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: gray.
- 3Read the lusterHold the specimen under a strong light. Luster: submetallic.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: anhedral grains.
Often confused with
Tredouxite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Ilmenite is the harder of the two (Mohs 5-6 vs. 3-3.5); streak differs, so Tredouxite leaves gray, Ilmenite leaves black to reddish brown; luster reads submetallic on Tredouxite and metallic to submetallic on Ilmenite.
How to tell apart: Magnetite is the harder of the two (Mohs 5.5-6.5 vs. 3-3.5); streak differs, so Tredouxite leaves gray, Magnetite leaves black; luster reads submetallic on Tredouxite and metallic to submetallic, may be dull on Magnetite.
Often found alongside tredouxite
Minerals reported to co-occur with tredouxite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NiSb₂O₆
- Mohs hardness
- 3-3.5
- Density
- 6.650 g/cm³
- Colors
- Streak
- Gray
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Tetragonal
- Crystal habit
- Anhedral grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In a podiform nickeliferous deposit in altered ultramafic rocks
Where rockhounds find tredouxite
Classic worldwide localities
- Bon Accord Ni-oxide deposit, southeast of Nelspruit, Republic of South Africa
Field-hunting tip
Where it forms: In a podiform nickeliferous deposit in altered ultramafic rocks. If you start seeing trevorite, bottinoite in float, you are in the right ground. Typical habit: anhedral grains. Train your eye for that shape before scanning the outcrop.
Common questions
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Find tredouxite on the map
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