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.
Is this moreauite?
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 moreauite with a known reference. Moreauite sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Moreauite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Moreauite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellow-green.
- 5Look at form & habitCrystal 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.
How to tell apart: Streak differs — Moreauite leaves yellow, Autunite leaves pale yellow; luster reads vitreous on Moreauite and pearly on Autunite.
How to tell apart: Streak differs — Moreauite leaves yellow, Torbernite leaves pale green.
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)₂(PO₄)₄(OH)·15H₂O
- Mohs hardness
- 3
- Density
- 4.2 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous, Acicular, Radiating Sprays
- Cleavage
- Perfect in One Direction
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
- Typical price
- $50-300 per thumbnail specimen
Where rockhounds find moreauite
Classic worldwide localities
- Kobokobo pegmatite, Democratic Republic of the Congo
Field-hunting tip
Look in granite pegmatites country — that is the host setting where moreauite typically forms. If you start seeing furongite, threadgoldite, meta-autunite in float, you are in the right ground. Field specimens usually show a fibrous, acicular, radiating sprays habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify moreauite?+
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Find moreauite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
