Metauranospinite is a secondary uranium mineral often found as bright yellow or greenish-yellow platy crystals or micaceous crusts. It is highly sought by collectors for its brilliant green fluorescence under ultraviolet light and is typically found in the oxidation zones of uranium-rich hydrothermal deposits.
Is this metauranospinite?
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 metauranospinite with a known reference. Metauranospinite 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: yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: pearly on {010}.
- 4Match the color rangeCompare against the expected color range: yellow, siskin green.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: platy crystals, micaceous aggregates.
Often confused with
Metauranospinite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Metauranospinite leaves yellow, Autunite leaves pale yellow; luster reads pearly on {010} on Metauranospinite and vitreous, pearly on {001} on Autunite.
How to tell apart: Streak differs, so Metauranospinite leaves yellow, Torbernite leaves pale green; luster reads pearly on {010} on Metauranospinite and vitreous, subadamantine, waxy, pearly on cleavages; becoming dull on dehydration to metatorbernite on Torbernite.
Often found alongside metauranospinite
Minerals reported to co-occur with metauranospinite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca(UO₂)₂(AsO₄)₂·8H₂O
- Mohs hardness
- 2-3
- Density
- 3.65 g/cm³
- Colors
- YellowSiskin green
- Streak
- Yellow
- Luster
- Pearly on {010}
- Transparency
- Translucent
- Crystal system
- Tetragonal
- Crystal habit
- Platy crystals, micaceous aggregates
- Cleavage
- Perfect on {001}
- Fluorescence
- Bright green under SW and LW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral of the oxide zone in a hydrothermal polymetallic barite–fluorite deposit
Where rockhounds find metauranospinite
Classic worldwide localities
- Clara mine, near Oberwolfach, Black Forest, Germany
Field-hunting tip
Where it forms: A secondary mineral of the oxide zone in a hydrothermal polymetallic barite–fluorite deposit. If you start seeing uraninite, gummite, pharmacosiderite in float, you are in the right ground. Typical habit: platy crystals, micaceous aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
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Find metauranospinite on the map
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