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.
Is this zellerite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch zellerite with a known reference. Zellerite sits at Mohs ~2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: earthy.
- 4Match the color rangeCompare against the expected color range: white yellow, lemon.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular.
Often confused with
Zellerite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Zellerite leaves white, Liebigite leaves yellow white; luster reads earthy on Zellerite and vitreous to pearly on cleavages on Liebigite.
How to tell apart: Luster reads earthy on Zellerite and vitreous to pearly on Andersonite.
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
- 3.25 g/cm³
- Colors
- White yellowLemon
- Streak
- White
- Luster
- Earthy
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular
- Cleavage
- None
- Fluorescence
- Weak mottled green under SW and LW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare weathering product of uranium ores, formed at low pH in the presence of oxidizing pyrite
Where rockhounds find zellerite
Classic worldwide localities
- Lucky Mc mine, Wind River Basin, Fremont Co., and the Pat No. 8 mine, Powder River Basin, Converse Co., Wyoming, USA
- White Canyon No. 1 mine, Frey Point, San Juan Co., Utah, USA
- Alta mine, Ambrosia Lake district, and Westwater Canyon, McKinley Co., New Mexico, USA
- Hatrurim Formation, Israel
- Jáchymov (Joachimsthal), Czech Republic
Field-hunting tip
Where it forms: A rare weathering product of uranium ores, formed at low pH in the presence of oxidizing pyrite. If you start seeing metazellerite, gypsum, limonite in float, you are in the right ground. Typical habit: acicular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify zellerite?+
Where is zellerite found?+
Is zellerite safe to handle?+
What rocks look like zellerite?+
What minerals are found with zellerite?+
What kind of rock does zellerite form in?+
What is zellerite used for?+
Find zellerite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
