Coconinoite is a rare, complex hydrated iron-aluminum-uranyl phosphate mineral that typically occurs as soft, powdery, or earthy yellow coatings on sandstone. It was first discovered in the uranium-bearing deposits of the Colorado Plateau and is highly sought after by collectors of radioactive minerals due to its restricted type localities.
Is this coconinoite?
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 coconinoite with a known reference. Coconinoite sits at Mohs 1-2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Coconinoite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Coconinoite typically shows a dull luster.
- 4Match the color rangeCompare against the expected color range: yellow, tan.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fine-grained earthy or powdery aggregates.
Often confused with
Coconinoite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Coconinoite leaves white, Autunite leaves pale yellow; luster reads dull on Coconinoite and pearly on Autunite.
How to tell apart: Streak differs, so Coconinoite leaves white, Torbernite leaves pale green; luster reads dull on Coconinoite and vitreous on Torbernite.
Often found alongside coconinoite
Minerals reported to co-occur with coconinoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe³⁺₂Al₂(UO₂)(PO₄)₄(OH)₂·20H₂O
- Mohs hardness
- 1-2
- Density
- 2.8 g/cm³
- Streak
- White
- Luster
- Dull
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Fine-grained Earthy or Powdery Aggregates
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Sandstone Hosted Uranium Deposits
Where rockhounds find coconinoite
Classic worldwide localities
- Coconino County, Arizona, USA
- San Juan County, Utah, USA
- Grand County, Utah, USA
Field-hunting tip
Look in sandstone hosted uranium deposits country, the host setting where coconinoite typically forms. If you start seeing gypsum, jarosite, uraninite in float, you are in the right ground. Field specimens usually show a fine-grained earthy or powdery aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify coconinoite?+
Where is coconinoite found?+
Is coconinoite safe to handle?+
What rocks look like coconinoite?+
What minerals are found with coconinoite?+
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What is coconinoite used for?+
Find coconinoite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
