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. Ronneburgite leaves a orange brownish streak.
- 3Read the lusterHold the specimen under a strong light. Ronneburgite typically shows a adamantine luster.
- 4Match the color rangeCompare against the expected color range: reddish brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals.
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. 2); streak differs, so Ronneburgite leaves orange brownish, Gypsum leaves white; luster reads adamantine on Ronneburgite and vitreous 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
- K₂CaMn(SO₄)₂(OH)₂
- Mohs hardness
- 3
- Density
- 2.98 g/cm³
- Colors
- Streak
- Orange Brownish
- Luster
- Adamantine
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals
- Cleavage
- Indistinct in One Direction
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Sedimentary Uranium Deposits
Where rockhounds find ronneburgite
Classic worldwide localities
- Ronneburg, Thuringia, Germany
Field-hunting tip
Look in sedimentary uranium deposits country, the host setting where ronneburgite typically forms. If you start seeing jarosite, gypsum, kaolinite in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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What rocks look like ronneburgite?+
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Find ronneburgite on the map
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