Běhounekite is a rare secondary uranyl sulfate mineral typically found as a result of the oxidation of uraninite. It manifests as delicate yellow crusts or small tabular crystals and is primarily known from the historic mining districts of the Czech Republic.

Hardness

Mohs

Luster

Vitreous

Streak

Gray to Greenish Gray

Transparency

Transparent

mineralrare

Běhounekite

Hardness: 2
Luster: Vitreous
Streak: Gray to Greenish Gray
Transparency: Transparent

Is this běhounekite?

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 běhounekite with a known reference. Běhounekite 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. Běhounekite leaves a gray to greenish gray streak.
3
Read the luster
Hold the specimen under a strong light. Běhounekite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: green.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: tabular crystals, crusts, pulverulent aggregates.

Often confused with

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

mineral

Johannite

Mohs 2

How to tell apart: Streak differs, so Běhounekite leaves gray to greenish gray, Johannite leaves pale green.

How to tell apart: Streak differs, so Běhounekite leaves gray to greenish gray, Zippeite leaves yellow.

Compare →

Often found alongside běhounekite

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

All properties

Chemical formula: UO₂(SO₄)·4H₂O
Mohs hardness: 2
Density: 3.5 g/cm³
Colors: Green
Streak: Gray to Greenish Gray
Luster: Vitreous
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Tabular Crystals, Crusts, Pulverulent Aggregates
Cleavage: Perfect On {100}
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Uranium-bearing Veins

Where rockhounds find běhounekite

Classic worldwide localities

Jáchymov, Czech Republic

Field-hunting tip

Look in hydrothermal uranium-bearing veins country, the host setting where běhounekite typically forms. If you start seeing johannite, jáchymovite, uranyl sulfates in float, you are in the right ground. Field specimens usually show a tabular crystals, crusts, pulverulent aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify běhounekite?+

Mohs hardness is 2. It typically shows a vitreous luster. The streak is gray to greenish gray. Common colors include green.

Where is běhounekite found?+

Notable localities include Jáchymov, Czech Republic.

Is běhounekite safe to handle?+

This mineral is radioactive. It contains toxic constituents. This mineral is radioactive and contains uranium; handle with gloves, avoid inhalation of dust, and store in a lead-lined container away from other mineral specimens and living spaces. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like běhounekite?+

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

What minerals are found with běhounekite?+

Běhounekite commonly co-occurs with Johannite, Jáchymovite, Uranyl sulfates. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does běhounekite form in?+

Běhounekite typically forms in hydrothermal uranium-bearing veins. Working float back to the host body is the standard way to chase a fresh occurrence.

What is běhounekite used for?+

Běhounekite is used in collector.

Find běhounekite on the map

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