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, so Paddlewheelite leaves yellow, Liebigite leaves pale yellow.

How to tell apart: Streak differs, so 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, 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.