Vanoxite is a rare hydrated vanadium oxide often found as earthy, black crusts or impregnations within sedimentary sandstone layers. It is typically associated with other vanadium-bearing minerals and is primarily of interest to collectors of rare secondary uranium-vanadium species.
Is this vanoxite?
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 vanoxite with a known reference. Vanoxite 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. Streak: brown black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: black, brownish black.
- 5Look at form & habitCrystal system: trigonal. Typical habit: crystalline, disseminated.
Often confused with
Vanoxite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Montroseite is the harder of the two (Mohs 5.5-6.5 vs. 2-3); streak differs, so Vanoxite leaves brown black, Montroseite leaves black; luster reads metallic on Vanoxite and submetallic on Montroseite.
How to tell apart: Streak differs, so Vanoxite leaves brown black, Corvusite leaves purplish blue-black; luster reads metallic on Vanoxite and “lusterous” on Corvusite.
How to tell apart: Streak differs, so Vanoxite leaves brown black, Pyrolusite leaves black, bluish black.
Often found alongside vanoxite
Minerals reported to co-occur with vanoxite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- V₄V₂O₁₃·8H₂O
- Mohs hardness
- 2-3
- Density
- 3.3-3.6 g/cm³
- Colors
- Streak
- Brown black
- Luster
- Metallic
- Transparency
- Opaque, transparent in thin fragments
- Crystal system
- Trigonal
- Crystal habit
- Crystalline, disseminated
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A replacement of fossil wood and cementing sandstone in Colorado Plateau-type U–V deposits
Where rockhounds find vanoxite
Classic worldwide localities
- Jo Dandy claim, Paradox Valley, Montrose Co., Colorado (type locality)
Field-hunting tip
Where it forms: A replacement of fossil wood and cementing sandstone in Colorado Plateau-type U–V deposits. If you start seeing gypsum, carnotite, hewettite in float, you are in the right ground. Typical habit: crystalline, disseminated. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify vanoxite?+
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Find vanoxite on the map
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