Ronneburgite is an extremely rare sulfate mineral first discovered in the uranium-bearing heaps of Ronneburg, Germany. It typically presents as small, reddish brown, tabular crystals formed in secondary sedimentary environments. Due to its limited occurrence and specific chemistry, it is primarily a prize for advanced mineral collectors.
Is this ronneburgite?
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 ronneburgite with a known reference. Ronneburgite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: orange brownish.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: reddish brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: microscopic crystals, prismatic, tabular.
Often confused with
Ronneburgite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Ronneburgite is noticeably harder (Mohs 3 vs. 2); streak differs, so Ronneburgite leaves orange brownish, Arcanite leaves white; luster reads adamantine on Ronneburgite and vitreous on Arcanite.
How to tell apart: Ronneburgite is noticeably harder (Mohs 3 vs. 1.5-2); streak differs, so Ronneburgite leaves orange brownish, Gypsum leaves white; luster reads adamantine on Ronneburgite and subvitreous, pearly on {010} cleavages, silky if fibrous on Gypsum.
Often found alongside ronneburgite
Minerals reported to co-occur with ronneburgite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₂MnV₄O₁₂
- Mohs hardness
- 3
- Density
- 2.84 g/cm³
- Colors
- Streak
- Orange brownish
- Luster
- Adamantine
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Microscopic crystals, prismatic, tabular
- Cleavage
- Indistinct in one direction
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral in a metamorphosed black shale uranium deposit
Where rockhounds find ronneburgite
Classic worldwide localities
- Ronneburg U deposit, near Gera, Thuringia, Germany
Field-hunting tip
Where it forms: A secondary mineral in a metamorphosed black shale uranium deposit. If you start seeing hummerite, gypsum, epsomite in float, you are in the right ground. Typical habit: microscopic crystals, prismatic, tabular. Train your eye for that shape before scanning the outcrop.
Common questions
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Find ronneburgite on the map
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