Hewettite is a rare, soft vanadium mineral that typically forms as delicate, dark red needle-like crystals or powdery coatings. It is primarily found in the oxidized zones of uranium-vanadium deposits, often forming as a result of the alteration of other vanadium species. Collectors prize it for its intense color, though its extreme fragility and solubility require careful handling.
Is this hewettite?
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 hewettite with a known reference. Hewettite sits at Mohs approx 1 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Hewettite leaves a brownish red streak.
- 3Read the lusterHold the specimen under a strong light. Hewettite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: dark red, deep red, maroon.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fibrous, acicular, needle-like, earthy aggregates.
Often confused with
Hewettite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Vanoxite is the harder of the two (Mohs 2-3 vs. approx 1); streak differs — Hewettite leaves brownish red, Vanoxite leaves black; luster reads pearly on Hewettite and dull on Vanoxite.
How to tell apart: Steigerite is the harder of the two (Mohs 2.5 vs. approx 1); streak differs — Hewettite leaves brownish red, Steigerite leaves yellow; luster reads pearly on Hewettite and dull on Steigerite.
How to tell apart: Pascoite is the harder of the two (Mohs 2 vs. approx 1); streak differs — Hewettite leaves brownish red, Pascoite leaves yellow; luster reads pearly on Hewettite and vitreous on Pascoite.
Often found alongside hewettite
Minerals reported to co-occur with hewettite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaV₆O₁₆·9H₂O
- Mohs hardness
- approx 1
- Density
- 2.6 g/cm³
- Streak
- Brownish Red
- Luster
- Pearly
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous, Acicular, Needle-like, Earthy Aggregates
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Vanadium-uranium Ore Deposits
- Typical price
- $20-150 for small specimens
Where rockhounds find hewettite
Classic worldwide localities
- Colorado, USA
- Utah, USA
- Mina Ragra, Peru
- Katanga, Congo
Field-hunting tip
Look in oxidized vanadium-uranium ore deposits country — that is the host setting where hewettite typically forms. If you start seeing carnotite, tyuyamunite, corvusite in float, you are in the right ground. Field specimens usually show a fibrous, acicular, needle-like, earthy aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find hewettite on the map
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