Fervanite is a rare hydrated iron vanadium oxide typically found as fibrous coatings or acicular clusters in vanadium-rich sandstone deposits. Collectors typically search for it as thin yellow-to-brown crusts within the secondary oxidation zones of uranium-vanadium mines in the Colorado Plateau.
Is this fervanite?
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 fervanite with a known reference. Fervanite sits at Mohs 2.5-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: yellowish brown.
- 3Read the lusterHold the specimen under a strong light. Luster: brilliant.
- 4Match the color rangeCompare against the expected color range: yellow, brown, pale green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fibrous.
Often confused with
Fervanite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Fervanite leaves yellowish brown, Carnotite leaves strontian-yellow; luster reads brilliant on Fervanite and dull, earthy; silky when crystalline on Carnotite.
How to tell apart: Streak differs, so Fervanite leaves yellowish brown, Pascoite leaves cadmium-yellow; luster reads brilliant on Fervanite and vitreous to subadamantine on Pascoite.
How to tell apart: Fervanite is noticeably harder (Mohs 2.5-3 vs. ~1); streak differs, so Fervanite leaves yellowish brown, Hewettite leaves brownish red; luster reads brilliant on Fervanite and silky to adamantine on Hewettite.
Often found alongside fervanite
Minerals reported to co-occur with fervanite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe₄V₄O₁₆·5H₂O
- Mohs hardness
- 2.5-3
- Density
- 3.28 g/cm³
- Colors
- Streak
- Yellowish brown
- Luster
- Brilliant
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- As an impregnation in sandstone (Colorado Plateau-type U–V deposits)
Where rockhounds find fervanite
Classic worldwide localities
- Monument No. 2 mine, Monument Valley, Apache Co., Arizona, USA
- Gold Quarry mine, near Carlin, Maggie Creek district, Eureka Co., Nevada, USA
- Wilson Springs (Potash Sulphur Springs) mine, Garland Co., Arkansas, USA
- Mounana uranium mine, Gabon
Field-hunting tip
Where it forms: As an impregnation in sandstone (Colorado Plateau-type U–V deposits). If you start seeing hewettite, metahewettite, carnotite in float, you are in the right ground. Typical habit: fibrous. Train your eye for that shape before scanning the outcrop.
Common questions
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Find fervanite on the map
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