Bassetite is a rare hydrated iron uranyl phosphate that typically occurs as thin, yellow-green tabular crystals. It is frequently found in the oxidation zones of uranium-bearing hydrothermal veins and is highly prized by collectors for its brilliant fluorescence.
Is this bassetite?
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 bassetite with a known reference. Bassetite 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. Bassetite leaves a pale yellow streak.
- 3Read the lusterHold the specimen under a strong light. Bassetite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellowish-green, brownish-yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, micaceous aggregates, crusts.
Often confused with
Bassetite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads vitreous on Bassetite and pearly on Autunite.
How to tell apart: Streak differs, so Bassetite leaves pale yellow, Meta-autunite leaves yellow; luster reads vitreous on Bassetite and pearly on Meta-autunite.
How to tell apart: Streak differs, so Bassetite leaves pale yellow, Torbernite leaves pale green.
Often found alongside bassetite
Minerals reported to co-occur with bassetite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe²⁺(UO₂)₂(PO₄)₂·8H₂O
- Mohs hardness
- 2-3
- Density
- 3.37 g/cm³
- Streak
- Pale Yellow
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Micaceous Aggregates, Crusts
- Cleavage
- Perfect Basal
- Fluorescence
- Bright Yellowish-green Under UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins in Granite, Oxidized Uranium Deposits
- Typical price
- $20-150 thumbnail, $200+ cabinet specimen
Where rockhounds find bassetite
Classic worldwide localities
- Wheal Basset, Cornwall, England
- Loděnice, Czech Republic
- Sabugal, Portugal
- Schneeberg, Germany
Field-hunting tip
Look in hydrothermal veins in granite, oxidized uranium deposits country, the host setting where bassetite typically forms. If you start seeing torbernite, uraninite, autunite in float, you are in the right ground. Field specimens usually show a tabular crystals, micaceous aggregates, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find bassetite on the map
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