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.
Is this běhounekite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch běhounekite with a known reference. Běhounekite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: gray to greenish gray.
- 3Read the lusterHold the specimen under a strong light. Luster: strongly vitreous.
- 4Match the color rangeCompare against the expected color range: green.
- 5Look at form & habitCrystal 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.
How to tell apart: Streak differs, so Běhounekite leaves gray to greenish gray, Johannite leaves pale green; luster reads strongly vitreous on Běhounekite and vitreous on Johannite.
How to tell apart: Streak differs, so Běhounekite leaves gray to greenish gray, Zippeite leaves yellow white; luster reads strongly vitreous on Běhounekite and vitreous on Zippeite.
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
- U(SO₄)₂·4H₂O
- Mohs hardness
- 2
- Density
- 3.62 g/cm³
- Colors
- Streak
- Gray to greenish gray
- Luster
- Strongly vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular crystals, crusts, pulverulent aggregates
- Cleavage
- Perfect on {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral on highly altered native arsenic in the oxidation zone of a polymetallic sulfarsenide deposit
Where rockhounds find běhounekite
Classic worldwide localities
- Jáchymov, Czech Republic
Field-hunting tip
Where it forms: A secondary mineral on highly altered native arsenic in the oxidation zone of a polymetallic sulfarsenide deposit. If you start seeing aresenic, arsenolite, kaatialaite in float, you are in the right ground. Typical habit: tabular crystals, crusts, pulverulent aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify běhounekite?+
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Find běhounekite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
