Zellerite is a rare secondary uranium mineral typically found as fibrous, yellow crusts in oxidized sandstone uranium deposits. It is best identified by its strong green-yellow fluorescence under UV light and its association with other secondary uranium minerals. Due to its radioactive nature, it is primarily sought after by advanced mineral collectors specializing in uranium-bearing species.

Hardness

Mohs

Luster

Earthy

Streak

White

Transparency

Opaque

mineralrare

Zellerite

Hardness: 2
Luster: Earthy
Streak: White
Transparency: Opaque

Is this zellerite?

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 zellerite with a known reference. Zellerite 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. Zellerite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Zellerite typically shows a earthy luster.
4
Match the color range
Compare against the expected color range: yellow, pale yellow.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: fibrous, earthy aggregates, crusts.

Often confused with

Zellerite 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 — Zellerite leaves white, Liebigite leaves pale yellow; luster reads earthy on Zellerite and vitreous on Liebigite.

How to tell apart: Luster reads earthy on Zellerite and vitreous on Andersonite.

Compare →

Often found alongside zellerite

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

All properties

Chemical formula: Ca(UO₂)(CO₃)₂·5H₂O
Mohs hardness: 2
Density: 2.5 g/cm³
Colors: Yellow Pale Yellow
Streak: White
Luster: Earthy
Transparency: Opaque
Crystal system: Orthorhombic
Crystal habit: Fibrous, Earthy Aggregates, Crusts
Cleavage: None
Fluorescence: Strong Yellow-green Under UV
Rarity: Rare
Uses: Collector
Host rock: Sedimentary Uranium Deposits in Sandstone
Typical price: $50-300 per specimen depending on size and quality

Where rockhounds find zellerite

Classic worldwide localities

Lucky Mc Mine, Wyoming, USA
Gas Hills, Wyoming, USA
Grand County, Utah, USA

Field-hunting tip

Look in sedimentary uranium deposits in sandstone country — that is the host setting where zellerite typically forms. If you start seeing gypsum, meta-autunite, uranyl carbonate minerals in float, you are in the right ground. Field specimens usually show a fibrous, earthy aggregates, crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify zellerite?+

Mohs hardness is 2. It typically shows a earthy luster. The streak is white. Common colors include yellow, pale yellow.

Where is zellerite found?+

Notable localities include Lucky Mc Mine, Wyoming, USA; Gas Hills, Wyoming, USA; Grand County, Utah, USA.

How much is zellerite worth?+

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

Is zellerite safe to handle?+

This mineral is radioactive. It contains toxic constituents. Zellerite contains uranium and is highly radioactive; store in lead-lined containers and wash hands thoroughly after handling. Avoid inhaling dust during preparation. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like zellerite?+

Zellerite 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 zellerite?+

Zellerite commonly co-occurs with Gypsum, Meta-autunite, Uranyl carbonate minerals. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does zellerite form in?+

Zellerite typically forms in sedimentary uranium deposits in sandstone. Working float back to the host body is the standard way to chase a fresh occurrence.

What is zellerite used for?+

Zellerite is used in collector.

Find zellerite on the map

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