Bergenite is a rare secondary uranium phosphate mineral that typically occurs as small tabular crystals or radiating sprays in hydrothermal deposits. It is highly valued by radioactive mineral collectors for its vibrant yellow color and strong fluorescence under ultraviolet light.

Hardness

2-3

Mohs

Luster

Vitreous

Streak

Pale yellow

Transparency

Semitransparent

mineralrare

Bergenite

Hardness: 2-3
Luster: Vitreous
Streak: Pale yellow
Transparency: Semitransparent

Is this bergenite?

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 bergenite with a known reference. Bergenite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: pale yellow.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: yellow, greenish yellow.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: acicular, tabular.

Often confused with

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

Often found alongside bergenite

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

All properties

Chemical formula: Ca₂Ba₄(UO₂)₉O₆(PO₄)₆·16H₂O
Mohs hardness: 2-3
Density: 4.1 g/cm³
Colors: Yellow Greenish yellow
Streak: Pale yellow
Luster: Vitreous
Transparency: Semitransparent
Crystal system: Monoclinic
Crystal habit: Acicular, tabular
Cleavage: Perfect
Fluorescence: Pale orange brown green under SW and LW UV
Rarity: Rare
Uses: Collector
Host rock: On a mine dump (Streuberg, Germany) and in uranium deposits (Black Forest, Germany)

Where rockhounds find bergenite

Classic worldwide localities

Streuberg, near Bergen, Saxony, and at Menzenschwand, Black Forest, Germany
Black Slate Formation, Republic of South Korea

Field-hunting tip

Where it forms: On a mine dump (Streuberg, Germany) and in uranium deposits (Black Forest, Germany). If you start seeing uranocircite, torbernite, autunite in float, you are in the right ground. Typical habit: acicular, tabular. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify bergenite?+

Mohs hardness is 2-3. Luster: vitreous. The streak is pale yellow. Common colors include yellow, greenish yellow.

Where is bergenite found?+

Notable localities include Streuberg, near Bergen, Saxony, and at Menzenschwand, Black Forest, Germany; Black Slate Formation, Republic of South Korea.

Is bergenite safe to handle?+

Bergenite contains uranium or thorium and calls for real care. This mineral is radioactive and contains uranium; handle with gloves and wash hands thoroughly after contact. Store in a lead-lined container or away from other specimens to minimize exposure.

What rocks look like bergenite?+

Bergenite is most often confused with Autunite, Torbernite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with bergenite?+

Bergenite commonly co-occurs with Uranocircite, Torbernite, Autunite, Dewindtite, Barian uranophane. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does bergenite form in?+

Where it forms: On a mine dump (Streuberg, Germany) and in uranium deposits (Black Forest, Germany). Working float back to the host body is the standard way to chase a fresh occurrence.

What is bergenite used for?+

Bergenite is used in collector.

Find bergenite on the map

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