Sailaufite is a rare calcium-manganese arsenate mineral discovered in the Spessart mountains of Germany. It typically forms thin, dark red-brown to black platy crystals within hydrothermal cavities, often associated with altered arsenic-bearing minerals.
Is this sailaufite?
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 sailaufite with a known reference. Sailaufite sits at Mohs ~3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: brown.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: dark red brown, black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: mammillary, tabular.
Often confused with
Sailaufite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Sailaufite is noticeably harder (Mohs ~3.5 vs. 2-2.5); streak differs, so Sailaufite leaves brown, Pharmacolite leaves white.
How to tell apart: Sailaufite is noticeably harder (Mohs ~3.5 vs. 2-2.5); streak differs, so Sailaufite leaves brown, Haidingerite leaves white.
Often found alongside sailaufite
Minerals reported to co-occur with sailaufite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ca,Na,□)₂Mn₃O₂(AsO₄)₂CO₃(H₂O)₂·H₂O
- Mohs hardness
- ~3.5
- Density
- 3.356 g/cm³
- Colors
- Dark red brownBlack
- Streak
- Brown
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Mammillary, tabular
- Cleavage
- Perfect {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A late-stage hydrothermal product in veins of Mn ore in rhyolite
Where rockhounds find sailaufite
Classic worldwide localities
- Hartkoppe hill, north of Ober-Sailauf, Spessart Mountains, northwestern Bavaria, Germany (type locality)
- Starlera deposit, Eastern Alps, Switzerland
Field-hunting tip
Where it forms: A late-stage hydrothermal product in veins of Mn ore in rhyolite. If you start seeing hausmannite, arseniosiderite, kutnohorite in float, you are in the right ground. Typical habit: mammillary, tabular. Train your eye for that shape before scanning the outcrop.
Common questions
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Find sailaufite on the map
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