RocksdayAutunite vs Torbernite
How to tell them apart
A radioactive uranium phosphate forming lemon-yellow square plates that glow green under UV.
Photo: Didier Descouens, CC BY-SA 4.0
A radioactive copper uranium phosphate forming emerald-green square plates.
Photo: Didier Descouens, CC BY-SA 3.0
Quick tests
- Streak (rub on unglazed porcelain): Autunite leaves a pale yellow streak; Torbernite leaves pale green.
Key differences
- Torbernite is darker emerald green and doesn't fluoresce.
- Autunite is yellower and glows under UV.
Side by side
| Property | Autunite | Torbernite |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 2–2.5 | 2–2.5 |
| Luster | Pearly | Vitreous to pearly |
| Streak | Pale yellow | Pale green |
| Colors | Yellow, Green | Green |
| Crystal system | Tetragonal | Tetragonal |
| Specific gravity | 3.1–3.2 | 3.2 |
| Formula | Ca(UO₂)₂(PO₄)₂·10–12H₂O | Cu(UO₂)₂(PO₄)₂·8–12H₂O |
| Found in | Autun, France; Daybreak mine, Washington | Musonoi, DR Congo; Cornwall, England |
Properties that are the same for both are grayed out.
How to identify autunite
- Yellow-green square flakes in stacks.
- Glows bright green under UV light.
- Radioactive.
Crystal system: Tetragonal
Full Autunite guide →How to identify torbernite
- Emerald-green square tablets.
- Not fluorescent (the copper suppresses it).
- Radioactive.
Crystal system: Tetragonal
Full Torbernite guide →Could you tell them apart from a blurry close-up?
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