Paulscherrerite is a rare uranium oxide mineral that forms as an alteration product of uraninite. It typically presents as small, dull, brownish octahedral crystals often associated with other uranium secondary minerals in hydrothermal deposits.

Hardness

5-6

Mohs

Streak

Yellow

Transparency

Translucent

mineralrareUraninite Group family

Paulscherrerite

Hardness: 5-6
Streak: Yellow
Transparency: Translucent

No image

Is this paulscherrerite?

4-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 paulscherrerite with a known reference. Paulscherrerite sits at Mohs 5-6, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: yellow.
3
Match the color range
Compare against the expected color range: canary yellow.
4
Look at form & habit
Crystal system: cubic. Typical habit: octahedral crystals.

Often confused with

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

mineral

Uraninite

Mohs 5-6

How to tell apart: Streak differs, so Paulscherrerite leaves yellow, Uraninite leaves brownish black, gray, olive-green, shining.

Compare →

Often found alongside paulscherrerite

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

All properties

Chemical formula: UO₂·xH₂O
Mohs hardness: 5-6
Density: 6.66 g/cm³
Colors: Canary yellow
Streak: Yellow
Transparency: Translucent
Crystal system: Cubic
Crystal habit: Octahedral crystals
Rarity: Rare
Uses: Collector, Scientific research
Host rock: A dehydration product of metaschoepite

Where rockhounds find paulscherrerite

Classic worldwide localities

Number 2 Workings, Radium Ridge, near Arkaroola, Northern Flinders Ranges, South Australia

Field-hunting tip

Where it forms: A dehydration product of metaschoepite. If you start seeing metaschoepite, β-uranophane, weeksite in float, you are in the right ground. Typical habit: octahedral crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify paulscherrerite?+

Mohs hardness is 5-6. The streak is yellow. Common colors include canary yellow.

Where is paulscherrerite found?+

Notable localities include Number 2 Workings, Radium Ridge, near Arkaroola, Northern Flinders Ranges, South Australia.

Is paulscherrerite safe to handle?+

Paulscherrerite contains uranium or thorium and calls for real care. Radioactive material; store in a lead-lined container and handle with gloves. Wash hands thoroughly after handling and avoid dust inhalation or ingestion.

What rocks look like paulscherrerite?+

Paulscherrerite is most often confused with Uraninite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with paulscherrerite?+

Paulscherrerite commonly co-occurs with Metaschoepite, Β-uranophane, Weeksite, Spriggite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does paulscherrerite form in?+

Where it forms: A dehydration product of metaschoepite. Working float back to the host body is the standard way to chase a fresh occurrence.

What is paulscherrerite used for?+

Paulscherrerite is used in collector, scientific research.

Find paulscherrerite on the map

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