Baumoite is a rare uranyl molybdate mineral typically found as small, bright yellow to orange-yellow platy crystals. It is primarily known from the Bauserach area in Germany, where it forms in oxidized hydrothermal uranium deposits. Due to its radioactive nature, it is strictly a mineral for advanced collectors and should be stored properly.
Is this baumoite?
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 baumoite with a known reference. Baumoite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Baumoite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Baumoite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellow-orange.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals, tabular, clusters.
Often confused with
Baumoite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Baumoite leaves yellow, Autunite leaves pale yellow; luster reads vitreous on Baumoite and pearly on Autunite.
How to tell apart: Uraninite is the harder of the two (Mohs 5-6 vs. 2); streak differs, so Baumoite leaves yellow, Uraninite leaves brownish-black to greenish-black; luster reads vitreous on Baumoite and submetallic to dull on Uraninite.
How to tell apart: Wulfenite is the harder of the two (Mohs 3 vs. 2); streak differs, so Baumoite leaves yellow, Wulfenite leaves white; luster reads vitreous on Baumoite and resinous on Wulfenite.
Often found alongside baumoite
Minerals reported to co-occur with baumoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- BaU₄(MoO₄)O₁₀(OH)₂·11H₂O
- Mohs hardness
- 2
- Density
- 4.95 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Platy Crystals, Tabular, Clusters
- Cleavage
- Perfect in One Direction
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
- Typical price
- $50-500 depending on specimen quality
Where rockhounds find baumoite
Classic worldwide localities
- Hesse, Germany
Field-hunting tip
Look in hydrothermal veins country, the host setting where baumoite typically forms. If you start seeing uraninite, wulfenite, cerussite in float, you are in the right ground. Field specimens usually show a platy crystals, tabular, clusters habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find baumoite on the map
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