Bayleyite is a rare secondary uranium carbonate typically found as a result of mine water evaporation in arid environments. It is most easily identified by its bright yellow-orange color and intense green fluorescence under ultraviolet light. Due to its high water content, it is sensitive to atmospheric conditions and should be stored in a controlled environment to prevent dehydration.

Hardness

2.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareBayleyite-Swartzite Group family

Bayleyite

Hardness: 2.5
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this bayleyite?

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 bayleyite with a known reference. Bayleyite sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Bayleyite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Bayleyite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, yellow-orange.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: prismatic crystals, drusy crusts, efflorescent coatings.

Often confused with

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

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

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Often found alongside bayleyite

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

All properties

Chemical formula: Mg₂(UO₂)(CO₃)₃·18H₂O
Mohs hardness: 2.5
Density: 2.16 g/cm³
Colors: Yellow Yellow-orange
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Prismatic Crystals, Drusy Crusts, Efflorescent Coatings
Cleavage: Perfect
Fluorescence: Bright Green Under SW and LW UV
Rarity: Rare
Uses: Collector
Host rock: Oxidized Zones of Uranium-bearing Hydrothermal Deposits
Typical price: $50-300 per specimen

Where rockhounds find bayleyite

Classic worldwide localities

Hillside Mine, Arizona, USA
Jáchymov, Czech Republic
Schneeberg, Germany

Field-hunting tip

Look in oxidized zones of uranium-bearing hydrothermal deposits country — that is the host setting where bayleyite typically forms. If you start seeing gypsum, andersonite, schröckingerite in float, you are in the right ground. Field specimens usually show a prismatic crystals, drusy crusts, efflorescent coatings habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify bayleyite?+

Mohs hardness is 2.5. It typically shows a vitreous luster. The streak is white. Common colors include yellow, yellow-orange.

Where is bayleyite found?+

Notable localities include Hillside Mine, Arizona, USA; Jáchymov, Czech Republic; Schneeberg, Germany.

How much is bayleyite worth?+

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

Is bayleyite safe to handle?+

This mineral is radioactive. It contains toxic constituents. This mineral is radioactive and contains uranium; handle with care using gloves, avoid inhalation of dust, and store in a sealed container away from living areas. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like bayleyite?+

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

What minerals are found with bayleyite?+

Bayleyite commonly co-occurs with Gypsum, Andersonite, Schröckingerite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does bayleyite form in?+

Bayleyite typically forms in oxidized zones of uranium-bearing hydrothermal deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is bayleyite used for?+

Bayleyite is used in collector.

Find bayleyite on the map

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