Paddlewheelite is a very rare uranyl carbonate mineral typically found as small, vibrant yellow platy crystals or crusts. It is named for its unique crystal structure that resembles a paddlewheel. It is predominantly found in the historic mining district of Jáchymov, Czech Republic, associated with other secondary uranium minerals.

Hardness

Mohs

Luster

Vitreous

Streak

Yellow

Transparency

Transparent

mineralrare

Paddlewheelite

Hardness: 2
Luster: Vitreous
Streak: Yellow
Transparency: Transparent

Is this paddlewheelite?

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 paddlewheelite with a known reference. Paddlewheelite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Paddlewheelite leaves a yellow streak.
3
Read the luster
Hold the specimen under a strong light. Paddlewheelite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, greenish-yellow.
5
Look at form & habit
Crystal system: triclinic. Typical habit: platy crystals, crusts.

Often confused with

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

mineral

Liebigite

Mohs 2.5

How to tell apart: Streak differs — Paddlewheelite leaves yellow, Liebigite leaves pale yellow.

How to tell apart: Streak differs — Paddlewheelite leaves yellow, Andersonite leaves white.

Compare →

Often found alongside paddlewheelite

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

All properties

Chemical formula: MgCu₂(UO₂)₂(CO₃)₃(OH)₄·18H₂O
Mohs hardness: 2
Density: 3.55 g/cm³
Colors: Yellow Greenish-yellow
Streak: Yellow
Luster: Vitreous
Transparency: Transparent
Crystal system: Triclinic
Crystal habit: Platy Crystals, Crusts
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Veins
Typical price: $50-300 per thumbnail specimen

Where rockhounds find paddlewheelite

Classic worldwide localities

Jáchymov, Czech Republic

Field-hunting tip

Look in hydrothermal veins country — that is the host setting where paddlewheelite typically forms. If you start seeing uraninite, liebigite, andersonite in float, you are in the right ground. Field specimens usually show a platy crystals, crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify paddlewheelite?+

Mohs hardness is 2. It typically shows a vitreous luster. The streak is yellow. Common colors include yellow, greenish-yellow.

Where is paddlewheelite found?+

Notable localities include Jáchymov, Czech Republic.

How much is paddlewheelite worth?+

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

Is paddlewheelite safe to handle?+

This mineral is radioactive. It contains toxic constituents. Contains uranium and copper; handle with gloves and wash hands thoroughly after handling. Store in a lead-lined or shielded container to prevent radiation exposure. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like paddlewheelite?+

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

What minerals are found with paddlewheelite?+

Paddlewheelite commonly co-occurs with Uraninite, Liebigite, Andersonite, Calcite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does paddlewheelite form in?+

Paddlewheelite typically forms in hydrothermal veins. Working float back to the host body is the standard way to chase a fresh occurrence.

What is paddlewheelite used for?+

Paddlewheelite is used in collector.

Find paddlewheelite on the map

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