Moreauite is a rare secondary uranium phosphate mineral occurring as delicate, fibrous to acicular radiating sprays. It is typically found in highly weathered uranium-bearing pegmatites and is notable for its bright yellow to yellow-green coloration. Due to its intense radioactivity and extreme rarity, it is almost exclusively held in advanced collector cabinets.

Hardness

2-3

Mohs

Luster

Vitreous

Streak

Light yellow

Transparency

Translucent to opaque

mineralrare

Moreauite

Hardness: 2-3
Luster: Vitreous
Streak: Light yellow
Transparency: Translucent to opaque

Is this moreauite?

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 moreauite with a known reference. Moreauite 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: vitreous.
4
Match the color range
Compare against the expected color range: greenish yellow, light yellow.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: fibrous, acicular, radiating sprays.

Often confused with

Moreauite 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 Moreauite leaves light yellow, Autunite leaves pale yellow.

How to tell apart: Streak differs, so Moreauite leaves light yellow, Torbernite leaves pale green.

Compare →

Often found alongside moreauite

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

All properties

Chemical formula: Al₃(UO₂)(PO₄)₃(OH)₂·13H₂O
Mohs hardness: 2-3
Density: 2.64 g/cm³
Colors: Greenish yellow Light yellow
Streak: Light yellow
Luster: Vitreous
Transparency: Translucent to opaque
Crystal system: Monoclinic
Crystal habit: Fibrous, acicular, radiating sprays
Cleavage: Good on {100}, micaceous
Rarity: Rare
Uses: Collector
Host rock: A rare secondary mineral in the oxidized uraniferous zone of a complex granite pegmatite

Where rockhounds find moreauite

Classic worldwide localities

Kobokobo pegmatite, Lusungu River district, Kivu Province, Congo (Zaire)

Field-hunting tip

Where it forms: A rare secondary mineral in the oxidized uraniferous zone of a complex granite pegmatite. If you start seeing furongite, ranunculite, phosphosiderite in float, you are in the right ground. Typical habit: fibrous, acicular, radiating sprays. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify moreauite?+

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

Where is moreauite found?+

Notable localities include Kobokobo pegmatite, Lusungu River district, Kivu Province, Congo (Zaire).

Is moreauite safe to handle?+

Moreauite contains uranium or thorium and calls for real care. Contains uranium and is radioactive. Handle with gloves, keep in a lead-lined or secure container, and avoid creating dust or ingesting particles.

What rocks look like moreauite?+

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

What minerals are found with moreauite?+

Moreauite commonly co-occurs with Furongite, Ranunculite, Phosphosiderite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does moreauite form in?+

Where it forms: A rare secondary mineral in the oxidized uraniferous zone of a complex granite pegmatite. Working float back to the host body is the standard way to chase a fresh occurrence.

What is moreauite used for?+

Moreauite is used in collector.

Find moreauite on the map

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