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. Streak: yellow white.
- 3Read the lusterHold the specimen under a strong light. Luster: waxy.
- 4Match the color rangeCompare against the expected color range: light yellow, straw 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, so Nováčekite leaves yellow white, Autunite leaves pale yellow; luster reads waxy on Nováčekite and vitreous, pearly on {001} on Autunite.
How to tell apart: Luster reads waxy on Nováčekite and pearly to dull on Meta-autunite.
How to tell apart: Streak differs, so Nováčekite leaves yellow white, Torbernite leaves pale green; luster reads waxy on Nováčekite and vitreous, subadamantine, waxy, pearly on cleavages; becoming dull on dehydration to metatorbernite on Torbernite.
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
- 3.25-3.7 g/cm³
- Colors
- Streak
- Yellow white
- Luster
- Waxy
- Transparency
- Semitransparent
- Crystal system
- Tetragonal
- Crystal habit
- Tabular crystals, micaceous
- Cleavage
- Perfect on {001}
- Fluorescence
- Dull green under SW and LW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In the oxidized zone of uranium-bearing polymetallic hydrothermal mineral deposits
Where rockhounds find nováčekite
Classic worldwide localities
- Woodrow area, Grants district, Valencia Co., New Mexico, USA
- Wichita Mountains, Comanche Co., Oklahoma, USA
- White King mine, Lake Co., Oregon, USA
- Schneeberg, Saxony, Germany
- Black Forest, from the Schmiedestollen dump, near Wittichen, the Anton mine, Heubachtal, near Schiltach, and the Michael mine, Weiler, near Lahr, Germany
- Ellweiler, Rhineland-Palatinate, Germany
Field-hunting tip
Where it forms: In the oxidized zone of uranium-bearing polymetallic hydrothermal mineral deposits. If you start seeing zeunerite, uranophane, schoepite in float, you are in the right ground. Typical habit: tabular crystals, micaceous. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify nováčekite?+
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Is nováčekite safe to handle?+
What rocks look like nováčekite?+
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Find nováčekite on the map
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