Ronneburgite is an extremely rare sulfate mineral first discovered in the uranium-bearing heaps of Ronneburg, Germany. It typically presents as small, yellow, tabular crystals formed in secondary sedimentary environments. Due to its limited occurrence and specific chemistry, it is primarily a prize for advanced mineral collectors.

Hardness

Mohs

Luster

Vitreous

Streak

Yellow

Transparency

Transparent

mineralrare

Ronneburgite

Hardness: 3
Luster: Vitreous
Streak: Yellow
Transparency: Transparent

Is this ronneburgite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch ronneburgite with a known reference. Ronneburgite sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Ronneburgite leaves a yellow streak.
3
Read the luster
Hold the specimen under a strong light. Ronneburgite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, yellowish-orange.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: tabular crystals.

Often confused with

Ronneburgite vs. its common look-alikes — and how to tell them apart in the field.

mineral

Arcanite

Mohs 3

How to tell apart: Streak differs — Ronneburgite leaves yellow, Arcanite leaves white.

How to tell apart: Ronneburgite is noticeably harder (Mohs 3 vs. 2); streak differs — Ronneburgite leaves yellow, Gypsum leaves white.

Compare →

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: Yellow Yellowish-orange
Streak: Yellow
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Tabular Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Sedimentary Uranium Deposits
Typical price: $50-300 per specimen

Where rockhounds find ronneburgite

Classic worldwide localities

Ronneburg, Thuringia, Germany

Field-hunting tip

Look in sedimentary uranium deposits country — that is 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

How do you identify ronneburgite?+

Mohs hardness is 3. It typically shows a vitreous luster. The streak is yellow. Common colors include yellow, yellowish-orange.

Where is ronneburgite found?+

Notable localities include Ronneburg, Thuringia, Germany.

How much is ronneburgite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like ronneburgite?+

Ronneburgite is most often confused with Arcanite, Gypsum. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with ronneburgite?+

Ronneburgite commonly co-occurs with jarosite, gypsum, kaolinite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does ronneburgite form in?+

Ronneburgite typically forms in sedimentary uranium deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is ronneburgite used for?+

Ronneburgite is used in collector.

Find ronneburgite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.