Wetherillite is a rare secondary uranium sulfate mineral that typically forms as a bright yellow efflorescence or thin platy crusts on sandstone. It is found in arid, uranium-rich mining districts where it occurs as a post-mining alteration product.
Is this wetherillite?
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 wetherillite with a known reference. Wetherillite 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. Wetherillite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Wetherillite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellow-orange.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals, tabular aggregates.
Often confused with
Wetherillite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside wetherillite
Minerals reported to co-occur with wetherillite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₂Mg(UO₂)₂(SO₄)₄·18H₂O
- Mohs hardness
- 2
- Density
- 3.51 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Platy Crystals, Tabular Aggregates
- Cleavage
- Perfect On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Uranium-bearing Sandstone
- Typical price
- $50-300 per specimen
Where rockhounds find wetherillite
Classic worldwide localities
- San Rafael Swell, Utah, USA
- Temple Mountain, Utah, USA
Field-hunting tip
Look in oxidized uranium-bearing sandstone country — that is the host setting where wetherillite typically forms. If you start seeing gypsum, jarosite, coquimbite in float, you are in the right ground. Field specimens usually show a platy crystals, tabular aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify wetherillite?+
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How much is wetherillite worth?+
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Find wetherillite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
