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.

Hardness

2-2.5

Mohs

Luster

Pearly

Streak

Yellow

Transparency

Translucent

mineralrareAutunite Group family

Vysokýite

Hardness: 2-2.5
Luster: Pearly
Streak: Yellow
Transparency: Translucent

Is this vysokýite?

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 vysokýite with a known reference. Vysokýite sits at Mohs 2-2.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Vysokýite leaves a yellow streak.
3
Read the luster
Hold the specimen under a strong light. Vysokýite typically shows a pearly luster.
4
Match the color range
Compare against the expected color range: yellow, yellowish-green.
5
Look at form & habit
Crystal system: tetragonal. Typical habit: platy crystals, crusts.

Often confused with

Vysokýite 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 — Vysokýite leaves yellow, Autunite leaves pale yellow.

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: Al(UO₂)₂(AsO₄)₂F·16H₂O
Mohs hardness: 2-2.5
Density: 3.3 g/cm³
Colors: Yellow Yellowish-green
Streak: Yellow
Luster: Pearly
Transparency: Translucent
Crystal system: Tetragonal
Crystal habit: Platy Crystals, Crusts
Cleavage: Perfect Basal
Fluorescence: Bright Green Under UV
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Uranium Veins
Typical price: $50-300 per specimen

Where rockhounds find vysokýite

Classic worldwide localities

Jáchymov, Czech Republic
Rudné Mountains, Czech Republic

Field-hunting tip

Look in hydrothermal uranium veins country — that is the host setting where vysokýite typically forms. If you start seeing uraninite, meta-autunite, arsenates in float, you are in the right ground. Field specimens usually show a platy crystals, crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify vysokýite?+

Mohs hardness is 2-2.5. It typically shows a pearly luster. The streak is yellow. Common colors include yellow, yellowish-green.

Where is vysokýite found?+

Notable localities include Jáchymov, Czech Republic; Rudné Mountains, Czech Republic.

How much is vysokýite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is vysokýite safe to handle?+

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

What rocks look like vysokýite?+

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

What minerals are found with vysokýite?+

Vysokýite commonly co-occurs with Uraninite, Meta-autunite, Arsenates. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does vysokýite form in?+

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

What is vysokýite used for?+

Vysokýite is used in collector.

Find vysokýite on the map

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