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 ~2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: yellow, orange-yellow.
- 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: Uraninite is the harder of the two (Mohs 5-6 vs. ~2.5); streak differs, so Baumoite leaves pale yellow, Uraninite leaves brownish black, gray, olive-green, shining; luster reads vitreous on Baumoite and submetallic to greasy, dull on Uraninite.
How to tell apart: Streak differs, so Baumoite leaves pale yellow, Wulfenite leaves white; luster reads vitreous on Baumoite and resinous, subadamantine to adamantine 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
- Ba₀.₅[(UO₂)₃O₈Mo₂(OH)₃](H₂O)₃
- Mohs hardness
- ~2.5
- Density
- 4.61 g/cm³
- Colors
- Streak
- Pale yellow
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Platy crystals, tabular, clusters
- Cleavage
- One excellent set
- Rarity
- Rare
- Uses
- Collector
- Host rock
- hydrothermal veins
Where rockhounds find baumoite
Classic worldwide localities
- 4 km northwest of the Radium Hill mine, South Australia
Field-hunting tip
Where it forms: hydrothermal veins. If you start seeing baryte, metatorbernite, phurcalite in float, you are in the right ground. Typical habit: platy crystals, tabular, clusters. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify baumoite?+
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Is baumoite safe to handle?+
What rocks look like baumoite?+
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Find baumoite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
