Uranopolycrase is a rare radioactive member of the euxenite group, typically found as an accessory mineral in granite pegmatites. It often presents as dark, metallic-looking prismatic crystals that are frequently metamict due to internal radiation damage.

Hardness

5.5-6.5

Mohs

Luster

Adamantine

Streak

Brown

Transparency

Opaque

mineralrareEuxenite Group family

Uranopolycrase

Hardness: 5.5-6.5
Luster: Adamantine
Streak: Brown
Transparency: Opaque

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Is this uranopolycrase?

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 uranopolycrase with a known reference. Uranopolycrase sits at Mohs 5.5-6.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Uranopolycrase leaves a brown streak.
3
Read the luster
Hold the specimen under a strong light. Uranopolycrase typically shows a adamantine luster.
4
Match the color range
Compare against the expected color range: red-brown.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: prismatic, tabular, or massive.

Often confused with

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

mineral

Euxenite-(Y)

Mohs 5.5-6.5

How to tell apart: Streak differs, so Uranopolycrase leaves brown, Euxenite-(Y) leaves yellowish-brown; luster reads adamantine on Uranopolycrase and submetallic on Euxenite-(Y).

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Often found alongside uranopolycrase

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

All properties

Chemical formula: (Y,Ca,Ce,U,Th)(Nb,Ta,Ti)₂O₆
Mohs hardness: 5.5-6.5
Density: 5.1-5.5 g/cm³
Colors: Red-brown
Streak: Brown
Luster: Adamantine
Transparency: Opaque
Crystal system: Orthorhombic
Crystal habit: Prismatic, Tabular, Or Massive
Cleavage: {100}, Good
Rarity: Rare
Uses: Collector
Host rock: Granite Pegmatites

Where rockhounds find uranopolycrase

Classic worldwide localities

San Piero in Campo, Elba, Italy

Field-hunting tip

Look in granite pegmatites country, the host setting where uranopolycrase typically forms. If you start seeing monazite, zircon, feldspar in float, you are in the right ground. Field specimens usually show a prismatic, tabular, or massive habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify uranopolycrase?+

Mohs hardness is 5.5-6.5. It typically shows a adamantine luster. The streak is brown. Common colors include red-brown.

Where is uranopolycrase found?+

Notable localities include San Piero in Campo, Elba, Italy.

Is uranopolycrase safe to handle?+

This mineral is radioactive. It contains toxic constituents. This mineral is radioactive and contains uranium and thorium. Store in a shielded container away from living areas and handle with care, washing hands thoroughly after contact. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like uranopolycrase?+

Uranopolycrase is most often confused with Euxenite-(Y). A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with uranopolycrase?+

Uranopolycrase commonly co-occurs with Monazite, Zircon, Feldspar, Quartz. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does uranopolycrase form in?+

Uranopolycrase typically forms in granite pegmatites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is uranopolycrase used for?+

Uranopolycrase is used in collector.

Find uranopolycrase on the map

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