Sherwoodite is a rare calcium vanadate mineral that typically occurs as vibrant blue, thin tabular crystals or as efflorescent crusts on sandstone. It is most commonly found in the vanadium-rich uranium deposits of the Colorado Plateau, where it forms in oxidized zones of ore bodies.
Is this sherwoodite?
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 sherwoodite with a known reference. Sherwoodite sits at Mohs ~2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale blue.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to earthy.
- 4Match the color rangeCompare against the expected color range: blue green, yellow green, dark blue black.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: tabular crystals, crusts, or coatings.
Often confused with
Sherwoodite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Sherwoodite leaves pale blue, Corvusite leaves purplish blue-black; luster reads vitreous to earthy on Sherwoodite and “lusterous” on Corvusite.
How to tell apart: Streak differs, so Sherwoodite leaves pale blue, Pascoite leaves cadmium-yellow.
How to tell apart: Sherwoodite is noticeably harder (Mohs ~2 vs. ~1); streak differs, so Sherwoodite leaves pale blue, Hewettite leaves brownish red; luster reads vitreous to earthy on Sherwoodite and silky to adamantine on Hewettite.
Often found alongside sherwoodite
Minerals reported to co-occur with sherwoodite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₅.₅(AlVV₁₂O₃₉)·28H₂O
- Mohs hardness
- ~2
- Density
- 2.8 g/cm³
- Colors
- Streak
- Pale blue
- Luster
- Vitreous to earthy
- Transparency
- Semitransparent
- Crystal system
- Tetragonal
- Crystal habit
- Tabular crystals, crusts, or coatings
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An oxidation product of lower valent vanadium minerals, on fracture surfaces and replacing fossil wood in Colorado Plateau-type U–V deposits; likely widely distributed
Where rockhounds find sherwoodite
Classic worldwide localities
- Peanut and Jo Dandy mines, Bull Canyon district, Uravan district, Montrose Co., at the Fall Creek mine, Placerville, San Miguel Co., and the Matchless mine, Calamity Mesa, Mesa Co., Colorado, USA
- Wilson Mesa, Grand Co., Utah, USA
- Shadyside mine, east Carrizo Mountains, San Juan Co., New Mexico, USA
- Joleo mine, Apache Co., Arizona, USA
- Minasragra, 46 km from Cerro de Pasco, Peru
Field-hunting tip
Where it forms: An oxidation product of lower valent vanadium minerals, on fracture surfaces and replacing fossil wood in Colorado Plateau-type U–V deposits; likely widely distributed. If you start seeing selenium, metatyuyamunite, melanovanadite in float, you are in the right ground. Typical habit: tabular crystals, crusts, or coatings. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify sherwoodite?+
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Find sherwoodite on the map
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