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

2-2.5

Mohs

Luster

Vitreous, dulling with dehydration

Streak

White

Transparency

Semitransparent

mineralrareBayleyite-Swartzite Group family

Bayleyite

Hardness: 2-2.5
Luster: Vitreous, dulling with dehydration
Streak: White
Transparency: Semitransparent

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 2-2.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous, dulling with dehydration.
4
Match the color range
Compare against the expected color range: yellow, pale yellow, yellowish white.
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, so Bayleyite leaves white, Liebigite leaves yellow white.

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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: 2-2.5
Density: 2.05 g/cm³
Colors: Yellow Pale yellow Yellowish white
Streak: White
Luster: Vitreous, dulling with dehydration
Transparency: Semitransparent
Crystal system: Monoclinic
Crystal habit: Prismatic crystals, drusy crusts, efflorescent coatings
Cleavage: None
Fluorescence: Yellow under SW and LW UV
Rarity: Rare
Uses: Collector
Host rock: As a coating or efflorescence with other secondary uranium minerals, which may be post-mining, typically in sediment-hosted uranium-bearing deposits

Where rockhounds find bayleyite

Classic worldwide localities

Hillside mine, about 5.5 km north of Bagdad, Eureka district, Yavapai Co., and in the Cole shaft, Bisbee, Cochise Co., Arizona, USA
Ambrosia Lake, Grants district, McKinley Co., New Mexico, USA
Hideout No. 1 (Tiger) mine, Deer Flats, White Canyon district, on the Coral claim, Elk Ridge, at the Mi Vida mine, San Juan Co., and from the Delta Group mine, San Rafael Swell, Emery Co., Utah, USA
Garfield and Rifle mines, north of Rifle, Garfield Co., from the J.J. mine, Montrose Co., and Schwartzwalder mine, Jefferson Co., Colorado, USA
Rabbit Lake uranium mine, Saskatchewan, Canada
Azegour, Morocco

Field-hunting tip

Where it forms: As a coating or efflorescence with other secondary uranium minerals, which may be post-mining, typically in sediment-hosted uranium-bearing deposits. If you start seeing schröckingerite, andersonite, swartzite in float, you are in the right ground. Typical habit: prismatic crystals, drusy crusts, efflorescent coatings. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify bayleyite?+

Mohs hardness is 2-2.5. Luster: vitreous, dulling with dehydration. The streak is white. Common colors include yellow, pale yellow, yellowish white.

Where is bayleyite found?+

Notable localities include Hillside mine, about 5.5 km north of Bagdad, Eureka district, Yavapai Co., and in the Cole shaft, Bisbee, Cochise Co., Arizona, USA; Ambrosia Lake, Grants district, McKinley Co., New Mexico, USA; Hideout No. 1 (Tiger) mine, Deer Flats, White Canyon district, on the Coral claim, Elk Ridge, at the Mi Vida mine, San Juan Co., and from the Delta Group mine, San Rafael Swell, Emery Co., Utah, USA; Garfield and Rifle mines, north of Rifle, Garfield Co., from the J.J. mine, Montrose Co., and Schwartzwalder mine, Jefferson Co., Colorado, USA; Rabbit Lake uranium mine, Saskatchewan, Canada.

Is bayleyite safe to handle?+

Bayleyite contains uranium or thorium and calls for real care. 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.

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 Schröckingerite, Andersonite, Swartzite, Gypsum, Tyuyamunite, Uranophane. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does bayleyite form in?+

Where it forms: As a coating or efflorescence with other secondary uranium minerals, which may be post-mining, typically in sediment-hosted uranium-bearing 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

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