Uranospinite is an uncommon hydrated calcium uranyl arsenate found primarily in the oxidation zones of uranium-rich ore deposits. Collectors recognize it by its vibrant yellow-green color and strong fluorescence under ultraviolet light, though it must be handled carefully due to its inherent radioactivity and arsenic content.
Is this uranospinite?
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 uranospinite with a known reference. Uranospinite 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: light yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: waxy, pearly on {001}.
- 4Match the color rangeCompare against the expected color range: siskin green, lemon yellow, yellow green.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: aggregates, platy.
Often confused with
Uranospinite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Uranospinite leaves light yellow, Autunite leaves pale yellow; luster reads waxy, pearly on {001} on Uranospinite and vitreous, pearly on {001} on Autunite.
How to tell apart: Streak differs, so Uranospinite leaves light yellow, Torbernite leaves pale green; luster reads waxy, pearly on {001} on Uranospinite and vitreous, subadamantine, waxy, pearly on cleavages; becoming dull on dehydration to metatorbernite on Torbernite.
Often found alongside uranospinite
Minerals reported to co-occur with uranospinite. 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)₂·10H₂O
- Mohs hardness
- 2-3
- Density
- 3.45 g/cm³
- Colors
- Streak
- Light yellow
- Luster
- Waxy, pearly on {001}
- Transparency
- Semitransparent
- Crystal system
- Orthorhombic
- Crystal habit
- Aggregates, platy
- Cleavage
- Perfect on {001}; distinct on {100}
- Fluorescence
- Bright lemon yellow under SW UV; yellowish green under LW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral in the oxide zone of U-As-bearing hydrothermal mineral deposits
Where rockhounds find uranospinite
Classic worldwide localities
- Clyde Long property, Elk Park, San Juan Co., Colorado, USA
- Spanish Fork, Utah Co., and at Paria, Kane Co., USA
- Orphan mine, Coconino Co., Arizona, USA
- Walpurgis vein, Weisser Hirsch mine, NeustädtelSchneeberg, Saxony, Germany
- Black Forest, from the Clara mine, near Oberwolfach, the Sophia mine, near Wittichen, at the Gottesehre mine, near Urberg, and from Menzenschwand, Germany
- Bühlskopf, near Ellweiler, Rhineland-Palatinate, Germany
Field-hunting tip
Where it forms: A secondary mineral in the oxide zone of U-As-bearing hydrothermal mineral deposits. If you start seeing metazeunerite, metauranocircite, uranophane in float, you are in the right ground. Typical habit: aggregates, platy. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify uranospinite?+
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Find uranospinite on the map
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