Hannebachite is a rare calcium sulfite hydrate typically found in volcanic environments as a secondary mineral. It occurs as delicate, transparent to white platy crystals, most famously discovered in the volcanic rocks of the Eifel region in Germany. It is highly sought after by mineral collectors due to its restricted occurrences and fragile nature.
Is this hannebachite?
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 hannebachite with a known reference. Hannebachite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Hannebachite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Hannebachite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, pale yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: platy or tabular crystals, often in radiating aggregates.
Often confused with
Hannebachite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside hannebachite
Minerals reported to co-occur with hannebachite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaSO₃·0.5H₂O
- Mohs hardness
- 2
- Density
- 2.66 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Platy or Tabular Crystals, Often in Radiating Aggregates
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Volcanic Ejecta, Fumarole Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find hannebachite
Classic worldwide localities
- Eifel Mountains, Germany
- Vesuvius, Italy
Field-hunting tip
Look in volcanic ejecta, fumarole deposits country — that is the host setting where hannebachite typically forms. If you start seeing thénardite, mirabilite, gypsum in float, you are in the right ground. Field specimens usually show a platy or tabular crystals, often in radiating aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find hannebachite on the map
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