Mianningite is a rare, complex uranium-bearing oxide mineral discovered in the Maoniuping carbonatite deposit in Sichuan, China. It is typically found as dark, submetallic grains associated with rare-earth element minerals and must be handled with appropriate radiation safety precautions due to its uranium content.

Hardness

5-5.5

Mohs

Luster

Submetallic

Streak

Light Brown

Transparency

Opaque

mineralrarePyrochlore Supergroup family

Mianningite

Hardness: 5-5.5
Luster: Submetallic
Streak: Light Brown
Transparency: Opaque

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Is this mianningite?

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 mianningite with a known reference. Mianningite sits at Mohs 5-5.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Mianningite leaves a light brown streak.
3
Read the luster
Hold the specimen under a strong light. Mianningite typically shows a submetallic luster.
4
Match the color range
Compare against the expected color range: black, brownish-black.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: anhedral to subhedral grains.

Often found alongside mianningite

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

All properties

Chemical formula: Mg(U,Fe,REE,Pb)₂(Ti,Fe,Nb,Ta)₂₀O₃₈(OH)₂
Mohs hardness: 5-5.5
Density: 5.73 g/cm³
Colors: Black Brownish-black
Streak: Light Brown
Luster: Submetallic
Transparency: Opaque
Crystal system: Orthorhombic
Crystal habit: Anhedral to Subhedral Grains
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Carbonatite
Typical price: $50-300 per specimen depending on size and association

Where rockhounds find mianningite

Classic worldwide localities

Maoniuping rare earth mine, Mianning, Sichuan, China

Field-hunting tip

Look in carbonatite country, the host setting where mianningite typically forms. If you start seeing bastnäsite, monazite, aegirine in float, you are in the right ground. Field specimens usually show a anhedral to subhedral grains habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify mianningite?+

Mohs hardness is 5-5.5. It typically shows a submetallic luster. The streak is light brown. Common colors include black, brownish-black.

Where is mianningite found?+

Notable localities include Maoniuping rare earth mine, Mianning, Sichuan, China.

How much is mianningite worth?+

Typical asking prices fall in the range of $50-300 per specimen depending on size and association. Quality, size, and provenance can move individual specimens well outside that range.

Is mianningite safe to handle?+

This mineral is radioactive. It contains toxic constituents. Mianningite contains uranium, thorium, and lead. Handle with care, wear gloves, store in a sealed container, and keep away from living spaces to avoid dust inhalation and radon exposure. Handle with care, avoid grinding or breathing dust, and store separately.

What minerals are found with mianningite?+

Mianningite commonly co-occurs with Bastnäsite, Monazite, Aegirine, Barite, Fluorite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does mianningite form in?+

Mianningite typically forms in carbonatite. Working float back to the host body is the standard way to chase a fresh occurrence.

What is mianningite used for?+

Mianningite is used in collector.

Find mianningite on the map

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