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, so Ronneburgite leaves yellow, Arcanite leaves white.

How to tell apart: Ronneburgite is noticeably harder (Mohs 3 vs. 2); streak differs, so 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, 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.