Arsenuranylite is a rare secondary uranium mineral that typically forms as bright yellow, platy, or micaceous aggregates within the oxidation zones of uranium-bearing hydrothermal veins. Due to its radioactive nature and potential for toxic arsenic exposure, it is intended strictly for professional or experienced collector display.

Hardness

2-3

Mohs

Luster

Pearly

Streak

Light yellow

Transparency

Semitransparent

mineralrare

Arsenuranylite

Hardness: 2-3
Luster: Pearly
Streak: Light yellow
Transparency: Semitransparent

Is this arsenuranylite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch arsenuranylite with a known reference. Arsenuranylite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: light yellow.
3
Read the luster
Hold the specimen under a strong light. Luster: pearly.
4
Match the color range
Compare against the expected color range: yellow, orange.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: scaly.

Often confused with

Arsenuranylite vs. its common look-alikes, and how to tell them apart in the field.

mineral

Autunite

Mohs 2-2.5

How to tell apart: Streak differs, so Arsenuranylite leaves light yellow, Autunite leaves pale yellow; luster reads pearly on Arsenuranylite and vitreous, pearly on {001} on Autunite.

How to tell apart: Luster reads pearly on Arsenuranylite and vitreous to pearly on Phosphuranylite.

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Often found alongside arsenuranylite

Minerals reported to co-occur with arsenuranylite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: Ca(UO₂)₄(AsO₄)₂(OH)₄·6H₂O
Mohs hardness: 2-3
Density: 4.25 g/cm³
Colors: Yellow Orange
Streak: Light yellow
Luster: Pearly
Transparency: Semitransparent
Crystal system: Orthorhombic
Crystal habit: Scaly
Cleavage: One, perfect
Rarity: Rare
Uses: Collector
Host rock: In the oxidized zone of a uranium deposit containing arsenic-bearing sulfides (Cherkasar deposit, Uzbekistan)

Where rockhounds find arsenuranylite

Classic worldwide localities

Cherkasar uranium deposit, 30 km northwest of Pap, Chatkal Range, Uzbekistan
Menzenschwand, Black Forest

Field-hunting tip

Where it forms: In the oxidized zone of a uranium deposit containing arsenic-bearing sulfides (Cherkasar deposit, Uzbekistan). If you start seeing paraschoepite, schoepite, metazeunerite in float, you are in the right ground. Typical habit: scaly. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify arsenuranylite?+

Mohs hardness is 2-3. Luster: pearly. The streak is light yellow. Common colors include yellow, orange.

Where is arsenuranylite found?+

Notable localities include Cherkasar uranium deposit, 30 km northwest of Pap, Chatkal Range, Uzbekistan; Menzenschwand, Black Forest.

Is arsenuranylite safe to handle?+

Arsenuranylite contains arsenic and uranium or thorium and calls for real care. This mineral is radioactive and contains arsenic. Handle with care, wear gloves when touching, avoid inhalation of dust, and store away from living areas in a lead-lined or sealed container.

What rocks look like arsenuranylite?+

Arsenuranylite is most often confused with Autunite, Phosphuranylite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with arsenuranylite?+

Arsenuranylite commonly co-occurs with Paraschoepite, Schoepite, Metazeunerite, Nováčekite, Uranospinite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does arsenuranylite form in?+

Where it forms: In the oxidized zone of a uranium deposit containing arsenic-bearing sulfides (Cherkasar deposit, Uzbekistan). Working float back to the host body is the standard way to chase a fresh occurrence.

What is arsenuranylite used for?+

Arsenuranylite is used in collector.

Find arsenuranylite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.