If you aren’t a dedicated mineral collector or a radiochemistry enthusiast, the name Abernathyite might sound like a fictional stone from a superhero movie. However, this rare secondary mineral is very real, strikingly beautiful, and carries a fascinating story that links 1950s geology with the complex world of uranium chemistry.
What is Abernathyite?
Abernathyite is a rare potassium uranyl arsenate hydrate mineral. It was first discovered in 1953 in the Fuemrol Mine in Emery County, Utah. Named after Jesse E. Abernathy, the mine operator who first found the specimens, it belongs to the autunite group—a family of minerals famous for their bright colors and radioactive properties.
Quick Facts:
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Chemical Formula: $K(UO_2)(AsO_4) \cdot 3H_2O$
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Color: Distinctive yellow to neon green.
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Luster: Vitreous (glassy) to pearly.
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Hardness: 2.5 on the Mohs scale (about the same as a fingernail).
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Crystal System: Tetragonal.
Appearance and Characteristics
One of the most striking things about Abernathyite is its visual appeal. It typically forms in small, transparent, platy crystals. While it may look delicate, its chemical makeup is quite specific.
The Glow Factor
Like many uranium-bearing minerals, Abernathyite is fluorescent. Under ultraviolet (UV) light, it emits a moderate to strong yellow-green glow. This is a characteristic of the uranyl ion ($UO_2^{2+}$) present in its structure.
Radioactivity
Because it contains uranium, Abernathyite is radioactive. While a small thumbnail specimen in a plastic container isn’t a major health hazard, it requires careful handling. Collectors usually store it in “perky boxes” to prevent the inhalation of any radioactive dust or radon gas buildup.
Where is it Found?
Abernathyite isn’t something you’ll find in your backyard. It is a secondary mineral, meaning it forms when primary uranium ores (like uraninite) are weathered or oxidized by groundwater.
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Utah, USA: The “type locality” remains the Fuemrol Mine.
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France: Notable specimens have been found in the Lodève District.
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Germany: Found in the Black Forest region.
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South Africa: Small deposits have been identified in the Northern Cape.
Why Should You Care?
You might wonder why scientists and collectors get excited about a tiny yellow crystal. Abernathyite is a “chemical cousin” to more common minerals like Autunite (calcium-based) and Metazeunerite (copper-based).
By studying how Abernathyite forms, geologists can understand how uranium and arsenic move through the earth’s crust. This is vital for environmental science, particularly in managing old mining sites and protecting groundwater from contamination.
Handling and Safety
If you are lucky enough to see a specimen in person, remember the three rules of radioactive minerals:
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Time: Limit the time you spend holding it.
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Distance: Keep it away from your living spaces.
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Shielding: Store it in a dedicated mineral case.
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Hygiene: Always wash your hands after handling any unsealed specimen.
Abernathyite is a perfect example of the hidden beauty found in the world of radioactive mineralogy—a mix of bright, neon colors and complex chemical history.