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?
4-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.
- 2Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 3Match the color rangeCompare against the expected color range: deep violet-brown.
- 4Look 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.
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[U(UO₂)₂O₄F₃](H₂O)₄
- Mohs hardness
- 2.5
- Colors
- Deep violet-brown
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Microcrystalline aggregates
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Formed by precipitation from U-containing aqueous solutions under partially reducing conditions most probably enhanced by consumption of oxygen during the oxidation of abundant pyrite present in the gangue
Where rockhounds find nollmotzite
Classic worldwide localities
- Grüner Grunde Mine, Germany
- Schachberg, Germany
Field-hunting tip
Where it forms: Formed by precipitation from U-containing aqueous solutions under partially reducing conditions most probably enhanced by consumption of oxygen during the oxidation of abundant pyrite present in the gangue. If you start seeing fluorite, barite in float, you are in the right ground. Typical habit: microcrystalline aggregates. 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?+
What is nollmotzite used for?+
Find nollmotzite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
