Nielsbohrite is a rare uranyl arsenate mineral characterized by its bright yellow, prismatic crystal habit. It is found in hydrothermal vein systems and is primarily sought after by advanced collectors of radioactive minerals due to its scarcity.

Hardness

Mohs

Luster

Vitreous to dull

Streak

Yellow

Transparency

Transparent

mineralrare

Nielsbohrite

Hardness: ~2
Luster: Vitreous to dull
Streak: Yellow
Transparency: Transparent

Is this nielsbohrite?

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 nielsbohrite with a known reference. Nielsbohrite 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. Streak: yellow.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous to dull.
4
Match the color range
Compare against the expected color range: yellow.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: euhedral crystals.

Often confused with

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

mineral

Autunite

Mohs 2-2.5

How to tell apart: Streak differs, so Nielsbohrite leaves yellow, Autunite leaves pale yellow.

How to tell apart: Streak differs, so Nielsbohrite leaves yellow, Torbernite leaves pale green.

Compare →

Often found alongside nielsbohrite

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

All properties

Chemical formula: K(UO₂)₃AsO₄(OH)₄·H₂O
Mohs hardness: ~2
Density: 5.45 g/cm³
Colors: Yellow
Streak: Yellow
Luster: Vitreous to dull
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Euhedral crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: A secondary mineral formed near oxidizing uraninite

Where rockhounds find nielsbohrite

Classic worldwide localities

Menzenschwand, Southern Black Forest, Baden-Württemberg, Germany (type locality)

Field-hunting tip

Where it forms: A secondary mineral formed near oxidizing uraninite. If you start seeing hematite, pyrite, schoepite in float, you are in the right ground. Typical habit: euhedral crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify nielsbohrite?+

Mohs hardness is ~2. Luster: vitreous to dull. The streak is yellow. Common colors include yellow.

Where is nielsbohrite found?+

Notable localities include Menzenschwand, Southern Black Forest, Baden-Württemberg, Germany (type locality).

Is nielsbohrite safe to handle?+

Nielsbohrite contains arsenic and uranium or thorium and calls for real care. Contains uranium and arsenic. Handle with gloves, wash hands thoroughly after contact, store in a sealed container, and keep away from living areas.

What rocks look like nielsbohrite?+

Nielsbohrite 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 nielsbohrite?+

Nielsbohrite commonly co-occurs with Hematite, Pyrite, Schoepite, Metazeunerite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does nielsbohrite form in?+

Where it forms: A secondary mineral formed near oxidizing uraninite. Working float back to the host body is the standard way to chase a fresh occurrence.

What is nielsbohrite used for?+

Nielsbohrite is used in collector.

Find nielsbohrite on the map

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