Nollmotzite is an extremely rare secondary uranium mineral typically found as small, deep violet-brown 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 vitreous luster.
- 4Match the color rangeCompare against the expected color range: deep violet-brown.
- 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, so Nollmotzite leaves yellow, Autunite leaves pale yellow; luster reads vitreous on Nollmotzite and pearly on Autunite.
How to tell apart: Streak differs, so Nollmotzite leaves yellow, Torbernite leaves pale green.
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
- Colors
- Streak
- Yellow
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Microcrystalline Aggregates
- Cleavage
- Perfect On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
Where rockhounds find nollmotzite
Classic worldwide localities
- Grüner Grunde Mine, Germany
- Schachberg, Germany
Field-hunting tip
Look in hydrothermal veins country, 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?+
Where is nollmotzite found?+
Is nollmotzite safe to handle?+
What rocks look like nollmotzite?+
What minerals are found with nollmotzite?+
What kind of rock does nollmotzite form in?+
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Find nollmotzite on the map
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