Oskarssonite is a rare aluminum fluoride mineral primarily found as a sublimation product in volcanic fumaroles. It typically occurs as small, delicate platy crystals and is often associated with other halide and sulfate minerals in active volcanic environments.
Is this oskarssonite?
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 oskarssonite with a known reference. Oskarssonite sits at Mohs 1-2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Oskarssonite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Oskarssonite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: trigonal. Typical habit: platy crystals, granular.
Often confused with
Oskarssonite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside oskarssonite
Minerals reported to co-occur with oskarssonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- AlF₃
- Mohs hardness
- 1-2
- Density
- 2.47 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Platy Crystals, Granular
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Volcanic Fumaroles
- Typical price
- $50-500 depending on specimen quality
Where rockhounds find oskarssonite
Classic worldwide localities
- Eldfell volcano, Heimaey, Iceland
Field-hunting tip
Look in volcanic fumaroles country — that is the host setting where oskarssonite typically forms. If you start seeing hematite, fluorite, anhydrite in float, you are in the right ground. Field specimens usually show a platy crystals, granular habit, so train your eye for that shape before scanning the outcrop.





