Abernathyite is a rare secondary uranium mineral that typically occurs as small, yellow, square tabular crystals. It is most often found in the oxidized zones of uranium-bearing sandstone deposits and is highly prized by collectors for its brilliant fluorescence under ultraviolet light.
Is this abernathyite?
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 abernathyite with a known reference. Abernathyite 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. Streak: pale yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: weakly vitreous.
- 4Match the color rangeCompare against the expected color range: yellow.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: tabular.
Often confused with
Abernathyite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Abernathyite leaves pale yellow, Meta-autunite leaves yellow; luster reads weakly vitreous on Abernathyite and pearly to dull on Meta-autunite.
How to tell apart: Luster reads weakly vitreous on Abernathyite and vitreous, subadamantine, waxy, pearly on cleavages; becoming dull on dehydration to metatorbernite on Torbernite.
Often found alongside abernathyite
Minerals reported to co-occur with abernathyite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K(UO₂)(AsO₄)·3H₂O
- Mohs hardness
- 2-3
- Density
- 3.31-3.57 g/cm³
- Colors
- Streak
- Pale yellow
- Luster
- Weakly vitreous
- Transparency
- Transparent
- Crystal system
- Tetragonal
- Crystal habit
- Tabular
- Cleavage
- Perfect on {001}
- Fluorescence
- Yellow green under SW and LW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral coating fractures in bleached asphaltic sandstone hosting a Colorado Plateau-type uranium deposit (Fuemrol No. 2 mine, Utah, USA)
Where rockhounds find abernathyite
Classic worldwide localities
- Found at the Fuemrole No. 2 mine, Temple Mountain, Emery Co., Utah, USA
- Cave Hills and Slim Buttes, Harding Co., South Dakota, USA
- West mine, Saguache Co. and the Clyde Long property, San Juan Co., Colorado, USA
- Tuba City, Coconino Co., Arizona, USA
- Riviéral mine, Lodève, Hérault, France
- Sailauf, northeast of Aschaffenburg, Bavaria, Germany
Field-hunting tip
Where it forms: A rare secondary mineral coating fractures in bleached asphaltic sandstone hosting a Colorado Plateau-type uranium deposit (Fuemrol No. 2 mine, Utah, USA). If you start seeing scorodite, zeunerite, heinrichite in float, you are in the right ground. Typical habit: tabular. Train your eye for that shape before scanning the outcrop.
Common questions
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Find abernathyite on the map
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