Vysokýite is a rare secondary uranium arsenate mineral found in the oxidation zones of uranium-bearing hydrothermal deposits. It is typically identified by its distinct platy yellow-green crystals and strong green fluorescence under ultraviolet light.
Is this vysokýite?
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 vysokýite with a known reference. Vysokýite 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: greenish white to gray.
- 3Read the lusterHold the specimen under a strong light. Luster: ‘Alabaster’.
- 4Match the color rangeCompare against the expected color range: yellow, yellowish-green.
- 5Look at form & habitCrystal system: triclinic. Typical habit: platy crystals, crusts.
Often confused with
Vysokýite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Vysokýite leaves greenish white to gray, Autunite leaves pale yellow; luster reads ‘alabaster’ on Vysokýite and vitreous, pearly on {001} on Autunite.
How to tell apart: Streak differs, so Vysokýite leaves greenish white to gray, Meta-autunite leaves yellow; luster reads ‘alabaster’ on Vysokýite and pearly to dull on Meta-autunite.
Often found alongside vysokýite
Minerals reported to co-occur with vysokýite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- U[AsO₂(OH)₂]₄·4H₂O
- Mohs hardness
- ~2
- Density
- 3.3903 g/cm³
- Colors
- Streak
- Greenish white to gray
- Luster
- ‘Alabaster’
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Platy crystals, crusts
- Cleavage
- Perfect on {100} and {001}
- Fluorescence
- Bright green under UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A post-mining secondary mineral developed by weathering in a humid climate of a Ag-As-Bi-Co-Ni-U hydrothermal vein-type deposit
Where rockhounds find vysokýite
Classic worldwide localities
- Jáchymov, Czech Republic
- Rudné Mountains, Czech Republic
Field-hunting tip
Where it forms: A post-mining secondary mineral developed by weathering in a humid climate of a Ag-As-Bi-Co-Ni-U hydrothermal vein-type deposit. If you start seeing native arsenic, běhounekite, štěpite in float, you are in the right ground. Typical habit: platy crystals, crusts. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify vysokýite?+
Where is vysokýite found?+
Is vysokýite safe to handle?+
What rocks look like vysokýite?+
What minerals are found with vysokýite?+
What kind of rock does vysokýite form in?+
What is vysokýite used for?+
Find vysokýite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
