Nováčekite is a rare uranyl arsenate mineral characterized by its vibrant yellow color and strong green fluorescence under UV light. It typically occurs as thin, square tabular crystals in the oxidation zones of uranium-bearing hydrothermal veins.
Is this nováčekite?
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 nováčekite with a known reference. Nováčekite sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Nováčekite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Nováčekite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, greenish-yellow, lemon-yellow.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: tabular crystals, micaceous.
Often confused with
Nováčekite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Nováčekite leaves yellow, Autunite leaves pale yellow; luster reads vitreous on Nováčekite and pearly on Autunite.
How to tell apart: Luster reads vitreous on Nováčekite and pearly on Meta-autunite.
How to tell apart: Streak differs — Nováčekite leaves yellow, Torbernite leaves pale green.
Often found alongside nováčekite
Minerals reported to co-occur with nováčekite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg(UO₂)₂(AsO₄)₂·10H₂O
- Mohs hardness
- 2.5
- Density
- 3.3-3.4 g/cm³
- Streak
- Yellow
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Tetragonal
- Crystal habit
- Tabular Crystals, Micaceous
- Cleavage
- Perfect Basal
- Fluorescence
- Bright Yellow-green Under UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Uranium Deposits
- Typical price
- $20-200 thumbnail
Where rockhounds find nováčekite
Classic worldwide localities
- Jáchymov, Czech Republic
- Johanngeorgenstadt, Germany
- White Canyon, Utah, USA
Field-hunting tip
Look in hydrothermal uranium deposits country — that is the host setting where nováčekite typically forms. If you start seeing uraninite, zeunerite, pharmacosiderite in float, you are in the right ground. Field specimens usually show a tabular crystals, micaceous habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find nováčekite on the map
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