Nollmotzite is an extremely rare secondary uranium mineral typically found as small, dull yellow crusts or powdery aggregates. It occurs as an alteration product of primary uranium minerals in hydrothermal vein environments and requires professional laboratory analysis for positive identification.
Is this nollmotzite?
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 nollmotzite with a known reference. Nollmotzite 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. Nollmotzite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Nollmotzite typically shows a earthy luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellow-green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: microcrystalline aggregates.
Often confused with
Nollmotzite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Nollmotzite leaves yellow, Autunite leaves pale yellow; luster reads earthy on Nollmotzite and pearly on Autunite.
How to tell apart: Streak differs — Nollmotzite leaves yellow, Torbernite leaves pale green; luster reads earthy on Nollmotzite and vitreous on Torbernite.
Often found alongside nollmotzite
Minerals reported to co-occur with nollmotzite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg(U₂O₈)·5H₂O
- Mohs hardness
- 2.5
- Density
- 4.15 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Earthy
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Microcrystalline Aggregates
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
- Typical price
- $100-500 thumbnail size
Where rockhounds find nollmotzite
Classic worldwide localities
- Grüner Grunde Mine, Germany
- Schachberg, Germany
Field-hunting tip
Look in hydrothermal veins country — that is the host setting where nollmotzite typically forms. If you start seeing uraninite, meta-autunite in float, you are in the right ground. Field specimens usually show a microcrystalline aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify nollmotzite?+
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Find nollmotzite on the map
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