Phosphuranylite is a rare secondary uranium phosphate that typically forms as vibrant yellow earthy crusts or thin coatings on other uranium minerals. Collectors should look for its strong yellow-green fluorescence under UV light, which is a key diagnostic feature. It is strictly for advanced collectors who are equipped to handle radioactive materials safely.
Is this phosphuranylite?
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 phosphuranylite with a known reference. Phosphuranylite 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. Phosphuranylite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Phosphuranylite typically shows a earthy luster.
- 4Match the color rangeCompare against the expected color range: yellow, golden yellow, orange-yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: platy crystals, earthy masses, coatings, crusts.
Often confused with
Phosphuranylite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Phosphuranylite leaves yellow, Autunite leaves pale yellow; luster reads earthy on Phosphuranylite and pearly on Autunite.
How to tell apart: Streak differs, so Phosphuranylite leaves yellow, Torbernite leaves pale green; luster reads earthy on Phosphuranylite and vitreous on Torbernite.
How to tell apart: Curite is the harder of the two (Mohs 4-5 vs. 2-3); streak differs, so Phosphuranylite leaves yellow, Curite leaves orange; luster reads earthy on Phosphuranylite and adamantine on Curite.
Often found alongside phosphuranylite
Minerals reported to co-occur with phosphuranylite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KCa(H₃O)₃(UO₂)₇(PO₄)₄O₄·8H₂O
- Mohs hardness
- 2-3
- Density
- 4.1-4.3 g/cm³
- Streak
- Yellow
- Luster
- Earthy
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Platy Crystals, Earthy Masses, Coatings, Crusts
- Cleavage
- Perfect On {010}
- Fluorescence
- Strong Yellow-green Under SW and LW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Uranium-bearing Pegmatites and Hydrothermal Deposits
- Typical price
- $20-150 for micro-mounts and small specimens
Where rockhounds find phosphuranylite
Classic worldwide localities
- Kobokobo, Democratic Republic of the Congo
- Ruggles Mine, New Hampshire, USA
- Wölsendorf, Bavaria, Germany
- Asselborn, Luxembourg
Field-hunting tip
Look in oxidized zones of uranium-bearing pegmatites and hydrothermal deposits country, the host setting where phosphuranylite typically forms. If you start seeing autunite, torbernite, curite in float, you are in the right ground. Field specimens usually show a platy crystals, earthy masses, coatings, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify phosphuranylite?+
Where is phosphuranylite found?+
How much is phosphuranylite worth?+
Is phosphuranylite safe to handle?+
What rocks look like phosphuranylite?+
What minerals are found with phosphuranylite?+
What kind of rock does phosphuranylite form in?+
What is phosphuranylite used for?+
Find phosphuranylite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
